Executive Summary

CVE-2019-25729 is a server-side template injection vulnerability in PDF Signer 3.0 that allows unauthenticated attackers to execute arbitrary code on the server.

The vulnerability occurs because attackers can inject malicious PHP commands through the CSRF-TOKEN cookie parameter.

By crafting cookie values containing template injection payloads like shell_exec(), attackers can execute system commands and retrieve sensitive information from the server.

Useful 0 Not Useful 0

Impact Analysis

This vulnerability can have severe impacts including unauthorized remote code execution on the affected server.

Attackers can execute arbitrary system commands, potentially gaining full control over the server.

They can retrieve sensitive information stored on the server, leading to data breaches and further exploitation.

Useful 0 Not Useful 0

Detection Guidance

This vulnerability can be detected by monitoring HTTP requests for suspicious or malicious CSRF-TOKEN cookie values that contain PHP code injection attempts, such as payloads using shell_exec().

One way to detect exploitation attempts is to capture and analyze HTTP traffic to identify requests with unusual or crafted CSRF-TOKEN cookies.

For example, using command-line tools like curl or wget, you can attempt to send crafted requests with injected PHP commands in the CSRF-TOKEN cookie to test if the server executes them (in a controlled and authorized environment).

• curl -v --cookie "CSRF-TOKEN=<?php echo shell_exec('id'); ?>" http://target-server/
• tcpdump or Wireshark to capture HTTP traffic and filter for requests containing suspicious CSRF-TOKEN cookie values.
• Review server logs for unexpected command execution or errors related to template rendering involving cookie parameters.

Useful 0 Not Useful 0

Mitigation Strategies

Immediate mitigation steps include disabling or restricting the processing of the CSRF-TOKEN cookie parameter to prevent injection of arbitrary PHP code.

Ensure proper input validation and sanitization of all cookie values, especially those used in server-side templates.

Apply patches or updates provided by the vendor or developer that address this server-side template injection vulnerability.

If patches are not available, consider temporarily disabling the vulnerable functionality or isolating the affected server to limit exposure.

Monitor logs and network traffic for signs of exploitation attempts and respond accordingly.

Useful 0 Not Useful 0

Compliance Impact

The vulnerability allows unauthenticated attackers to execute arbitrary code on the server and retrieve sensitive information. This exposure of sensitive data and unauthorized system access can lead to non-compliance with data protection regulations such as GDPR and HIPAA, which require strict controls to protect personal and sensitive information from unauthorized access and breaches.

Specifically, the ability to execute arbitrary commands and access sensitive information increases the risk of data breaches, which are subject to mandatory reporting and can result in penalties under these regulations.

Useful 0 Not Useful 0