When it comes to managing networks—whether on-premise or in the cloud—one of the biggest challenges is understanding what’s happening with your traffic. That's where flow logs and traffic mirroring come in. These tools provide essential visibility into network activity, helping with everything from troubleshooting to detecting suspicious behavior.
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Flow Logs: The Call Records of Your Network
Think of flow logs as the "call records" of your network. Just like a phone bill shows who called whom, at what time, and for how long, flow logs show similar information but for network traffic.
For example, you can track:
Which source IP is communicating with which destination IP
Ports being used
Timestamp of the traffic
Volume of data transferred
This level of detail is invaluable for general troubleshooting and tracking unusual activity in your network. Flow logs give you a high-level summary, making it easy to see patterns and spot anomalies.
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Storing and Analyzing Flow Logs
In AWS, flow logs can be stored in Amazon S3 for archiving or sent to CloudWatch Logs for real-time analysis. Sending them to CloudWatch gives you the ability to:
Query logs directly for ad-hoc analysis
Set up alerts (e.g., for detecting high bandwidth usage)
For more advanced analysis, you can export flow logs to systems like Elasticsearch or Splunk, where you can take advantage of their powerful search capabilities to dig deeper into network behavior.
To get started with flow logs, check out the AWS documentation.
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Traffic Mirroring: Dive into Network Traffic
While flow logs provide summaries, traffic mirroring lets you go a step further by capturing the actual network traffic. This is useful for tasks like network intrusion detection. With traffic mirroring, you can copy traffic from a network interface on an EC2 instance and send it to a monitoring instance, which can be in the same VPC or even in a separate account.
This is particularly helpful for security investigations. For instance, during the COVID-19 pandemic, the company CRED used traffic mirroring to enhance network inspection for employees working from home.
Traffic mirroring allows you to:
Filter traffic, so you only capture the data you need
Send traffic to a dedicated security enclave for analysis
Monitor traffic from multiple locations, even across different AWS accounts
If you’re interested in setting this up, AWS has a helpful guide..
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Cloud Incident Response: Why It’s Different and How to Prepare
One of the golden rules of incident response (IR) in the cloud is simple: Go to where the data is. Investigating incidents directly in the cloud offers significant advantages:
Faster access to data
Scalable computing resources for analyzing large datasets
Built-in automation tools to speed up the investigation
But to make the most of these benefits, you need to plan ahead. For example, ensure that your security team has access to cloud assets before an incident occurs. This avoids delays in gathering the necessary data when time is of the essence.
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Gaining Access to Cloud Assets
Getting access to cloud data for incident response can be challenging if not properly planned. At a minimum, your security team should have direct communication lines with cloud administrators to quickly gain access. However, it’s better to set up federated authentication so the security team can assume roles in AWS accounts as needed. Tools like AWS Organizations can help manage access and ensure consistent logging across accounts.
Read more about preparing for cloud incidents.
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Using the Cloud to Build Incident Response Labs
One of the exciting possibilities of using cloud infrastructure for incident response is the ability to quickly spin up investigative labs. In a cloud environment, you can:
Scale analysis hosts on demand
Quickly access network and host data
Create security enclaves (i.e., isolated AWS accounts) for storing and analyzing sensitive information
AWS Control Tower offers a framework for organizing and managing these security accounts, which act as a boundary to protect data from potential intruders in production accounts. You can even create forensic accounts specifically for investigating incidents.
Additionally, tools like Velociraptor are useful for triaging data and live analysis, even in the cloud. Building out these capabilities in the cloud enables you to respond more efficiently to incidents while reducing risk.
For more information, check out AWS’s guidance on forensic investigation strategies.
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When it comes to incident response (IR) in the cloud, especially with AWS, having the right security accounts and forensic tools in place is essential for efficient investigations. Cloud-based incidents often involve extensive log analysis, which can be complex given the various ways AWS stores and manages logs. Additionally, dealing with network forensics in environments using VPCs and EC2 instances requires preparation with tools for both disk-based and network-based analysis.
Accessing Logs for Cloud Investigations
One of the main challenges in cloud incident response is accessing and analyzing logs. Logs can be stored in various formats and locations within AWS. For example:
VPC flow logs might be archived in S3 buckets or sent to CloudWatch for real-time processing.
Organizations may centralize logs in dedicated log archive accounts or aggregate them into a security account for streamlined access.
When preparing your environment, create a clear logging architecture across all accounts, ensuring read-only access to critical logs. This allows your security team to quickly access the data without worrying about unauthorized modifications.
Additionally, you may configure a security account to subscribe to logs from other accounts via CloudWatch. This can centralize log management, allowing custom views and integration with SIEM tools for better incident tracking. However, be mindful of potential costs and redundancy if logs are already being stored elsewhere.
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Capturing Network Data: VPC Traffic Mirroring and PCAP
If your organization uses VPCs and EC2 instances, VPC traffic mirroring is a critical tool for capturing network traffic in real-time. This feature can provide PCAP data, which is often pivotal in identifying and analyzing suspicious network behavior. By setting up traffic mirroring, you can send real-time network data to your analysis environment, ensuring that no important traffic is missed during an investigation.
Forensic readiness in AWS also includes using Elastic Block Storage (EBS) snapshots to capture disk images. Snapshots are quick and easy to create, allowing you to preserve the state of an EC2 instance at a specific moment in time. These snapshots can be shared with your security account for further analysis. Be sure that your team has access to the relevant encryption keys if the EBS volume is encrypted.
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Ensuring Secure and Compliant Data Handling
When dealing with sensitive data, security and compliance are paramount. For example:
Use S3 Object Lock to make logs immutable, preventing them from being altered or deleted during an investigation.
Enable S3 Versioning to keep track of changes and allow easy recovery of previous versions.
Implement MFA Delete to enforce multi-factor authentication before any versions can be deleted, adding an extra layer of protection.
For long-term storage, S3 Glacier offers a cost-effective solution for storing logs and forensic data, while still providing the flexibility to retrieve data when needed.
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Deploying Security Tools Across AWS Regions
One of the unique aspects of working in AWS is the ability to deploy resources across different regions. Since AWS has 25+ regions, ensure that your security tools can be easily deployed wherever your company operates. This is important for:
Speed: It may be quicker to access data from the same region where it was generated rather than transferring it across regions.
Cost: Cross-region data transfers incur additional fees, so keeping analysis local can save money.
Compliance: In some cases, privacy laws may restrict moving data across national borders, even within AWS.
Deploying clean instances of your security tooling in each region ensures you can respond quickly without jurisdictional or logistical hurdles.
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Secure Communications During Incident Response
During an incident, secure communication is critical. Advanced attackers have been known to monitor security teams, so ensure you have a secure communication plan in place. This could involve using dedicated cloud resources outside your usual business channels to avoid being compromised during critical moments. Whether hosted on AWS or another provider, the key is to have a secure, well-thought-out system in place before an incident occurs.
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Automating Triage and Evidence Collection
Automation plays a vital role in speeding up incident response. AWS Systems Manager (SSM) is a powerful tool for automating tasks, such as running triage scripts or gathering evidence from EC2 instances. The SSM agent, commonly installed on AWS hosts, can also be used on-premise or in other cloud environments, providing flexibility across different systems.
For example, incident responders can use the SSM agent to attach a shared EBS volume to a running EC2 instance, capturing volatile memory or other critical data without using privileged accounts. This minimizes risk and ensures evidence is collected efficiently.
AWS also provides a range of automation scripts that leverage Systems Manager to extract data for later analysis, significantly improving response times during an incident.
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Practice and Plan for Incident Response
Just as in sports, the key to successful incident response is practice. AWS offers incident simulation scenarios to help teams prepare for real-world situations. These simulations help identify gaps in your plan and provide opportunities to optimize processes. By regularly practicing these scenarios, your team can improve their confidence and ability to handle incidents effectively.
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Conclusion
Building an efficient incident response strategy in AWS requires a combination of planning, tooling, and automation. By leveraging AWS features like flow logs, VPC traffic mirroring, and EBS snapshots, security teams can gain deep visibility into both network and disk activity. Automation tools, such as AWS Systems Manager, further enhance the response by simplifying evidence collection and triage
Akash Patel
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