Prevent Session Token Replay
Protecting session tokens is a critical part of defending against Adversary-in-the-Middle (AiTM) attacks. Even if an attacker manages to steal a user’s session token, they cannot use it if proper protections are in place.
This page explains how binding session tokens to devices and other controls prevent attackers from replaying sessions to bypass Multi-Factor Authentication (MFA).
Why Session Token Replay Matters
AiTM attacks often capture session tokens after a user completes MFA. If attackers can reuse these tokens, they gain access to the account without needing the user’s credentials or MFA approval.
Preventing session token replay ensures that stolen tokens cannot be used on unauthorized devices, stopping attackers from hijacking active sessions.
Key Technologies
1. Entra Token Protection (Token Binding)
Binds the session token to a specific device or session context.
Tokens are only valid on the original device used for authentication.
Any attempt to replay the token from a different device is automatically rejected.
2. Shortened Session Token Lifetimes
Reduces the window of opportunity for attackers to reuse tokens.
Even if a token is captured, it expires quickly, limiting potential damage.
Helps enforce continuous security without interrupting legitimate user sessions.
How These Measures Prevent AiTM
Device Binding: Attackers cannot replay tokens from AiTM infrastructure because the token is tied to the legitimate user’s device.
Token Expiration: Short token lifetimes minimize the risk of session hijacking.
Combined Protection: Together, these technologies make it extremely difficult for attackers to gain unauthorized access, even if MFA is bypassed or credentials are stolen.