Multiple failed login attempts using expired tokens are followed by successful access with a valid...

This scenario strongly suggests a race condition attack in the application’s token validation logic, as described in CEH v13 Web Application Hacking. A race condition occurs when an application processes multiple requests simultaneously and fails to properly synchronize validation checks.

The presence of multiple failed attempts using expired tokens followed by successful access within a short time window indicates the attacker exploited a timing flaw. During this window, the system may have inconsistently validated token expiration, allowing an expired token to be accepted.

Option A is unlikely because the logs specifically reference expired tokens. Option B is incorrect because replaying expired tokens should fail unless a validation flaw exists. Option C is highly improbable due to token entropy.

CEH v13 highlights race conditions as advanced logic flaws that are difficult to detect and often missed during standard testing. They are commonly exploited in authentication, payment processing, and session management systems.

Therefore, Option D is the correct and CEH-aligned answer.