Sunturai
Back to results
InformationalSplunk security contentMichael Haag +1

Tomcat Session File Upload Attempt

This detection identifies potential exploitation of CVE-2025-24813 in Apache Tomcat through the initial stage of the attack. This first phase occurs when an attacker attempts to upload a malicious serialized Java…

Description

This detection identifies potential exploitation of CVE-2025-24813 in Apache Tomcat through the initial stage of the attack. This first phase occurs when an attacker attempts to upload a malicious serialized Java object with a .session file extension via an HTTP PUT request. When successful, these uploads typically result in HTTP status codes 201 (Created) or 409 (Conflict) and create the foundation for subsequent deserialization attacks by placing malicious content in a location where Tomcat's session management can access it.

Detection logic

Detection requirements

Platform
ContainersESXiIaaSLinuxmacOSNetwork DevicesWindows

The rule states no platform. This is derived from the 2 ATT&CK techniques it maps to.

Log source category
nginx_access

Known benign triggers

  • Some legitimate applications might use PUT requests to create .session files, especially in custom implementations that leverage Tomcat's session persistence mechanism. Verify if the detected activity is part of a normal application flow or if it correlates with other suspicious behavior, such as subsequent GET requests with manipulated JSESSIONID cookies.

Detections can measure how the public catalogue is used — which detections people look for, and which pages bring them here. It sets a cookie that recognises this browser for 180 days. It is never linked to an account and never follows you to other sites. Privacy notice