Understanding Token Stealing in Windows Environments

Updated in 13 Feb,2025

Introduction to Security Tokens in Windows

Every time you log into a Windows system or run a process, the system generates a security token. This token defines the security context of the session, determining what actions and resources you can access. Security tokens contain essential information, including user privileges and permissions.

There are special types of tokens called impersonation tokens and delegate tokens that play a crucial role in access control and Single Sign-On (SSO).

• Impersonation Tokens allow a process to temporarily assume the security context of another user but only within the local system.

• Delegate Tokens are more powerful, enabling authentication even across network resources. These are commonly present during interactive logons but may also be used by certain non-interactive Microsoft services.

The most common privilege escalation techniques—token stealing.

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What is Token Stealing?

Token stealing is an attack technique where a malicious actor extracts and reuses security tokens to escalate privileges or perform unauthorized actions. If a valid token is available on a system, an attacker with the SeImpersonate privilege (or administrative/system-level rights) can hijack that token and use it for various purposes.

Like

• Gaining higher privileges (e.g., escalating from a local admin to a domain admin)

• Adding or modifying user accounts and group memberships

• Accessing remote systems via admin shares or tools like PsExec (for delegate tokens)

Why is Token Stealing a Serious Threat?

Attackers commonly use token stealing when they cannot retrieve password hashes directly from LSASS (Local Security Authority Subsystem Service). This is especially useful in newer Windows versions (Windows 8.1 and later) where LSASS is protected against direct dumping.

Moreover, servers are prime targets for token stealing since multiple users—including administrators—often log in simultaneously. If an administrator connects via Remote Desktop Protocol (RDP) and fails to log out properly, their token remains active and vulnerable to theft.

How Does Token Stealing Work?

A common method for stealing tokens is through Mimikatz, a widely used post-exploitation tool. Here’s how an attacker typically executes a token stealing attack:

• The attacker gains access to a system with local administrator privileges.

• They run Mimikatz and execute the command:

token::elevate /domainadmin

• This searches for available domain administrator tokens on the system.

• If a token is found, Mimikatz loads it into the process memory, allowing the attacker to operate as a domain admin.

This technique effectively grants an attacker full control over the system and potentially the entire domain.

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Preventing Token Stealing

1. Minimize Use of High-Privilege Accounts

• Avoid logging into systems interactively with highly privileged accounts.

• Use Just Enough Administration (JEA) and Just-In-Time (JIT) Privileges to minimize the exposure of admin accounts.

2. Properly Manage RDP Sessions

• Always log out of RDP sessions properly instead of simply closing the session.

• Use Group Policy to enforce a timeout for disconnected sessions, ensuring that inactive sessions are terminated automatically.

3. Enable Security Features in Modern Windows Versions

• Use Restricted Admin Mode (Windows 8.1+), which prevents credential exposure during RDP sessions.

• Implement Remote Credential Guard (Windows 10/Server 2016+), which protects credentials from being stolen across network logins.

4. Use the Protected Users Security Group

In Windows 8.1 and later, the Protected Users security group prevents members from generating delegate tokens, even during interactive logins. While it may not work for all administrative functions, it is a powerful security measure for sensitive accounts like domain admins.

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Conclusion

Token stealing remains a critical security concern in Windows environments. By understanding how tokens work and how attackers exploit them, security professionals can implement better defenses to protect high-value accounts.

With cybersecurity, the key is always proactive defense—don't wait for an attack to happen before taking action!

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