Xdebug remote code execution via xdebug.remote_connect_back

What it is Xdebug remote code execution via xdebug.remote_connect_back?

The Xdebug remote code execution (RCE) module is designed to detect a misconfiguration in the XDebug extension for PHP that can lead to a high severity vulnerability. XDebug is an extension for PHP that enhances development with features like stack traces, code coverage, and debugging support. However, if the xdebug.remote_connect_back setting is enabled without proper access controls, it can allow remote attackers to execute arbitrary code on the server.

This module focuses on identifying instances where the xdebug.remote_connect_back setting is misconfigured, potentially exposing the application to remote code execution attacks. It is important to address this vulnerability promptly to prevent unauthorized access and potential compromise of sensitive data.

This module was authored by an expert in the field of web application security.

Impact

A successful exploitation of the Xdebug remote code execution vulnerability can have severe consequences for the affected application and its users. An attacker who can exploit this vulnerability can execute arbitrary code on the server, potentially gaining full control over the system. This can lead to unauthorized access, data theft, and further compromise of the application and its environment.

How the module works?

The Xdebug remote code execution module works by sending a specific HTTP request to the target application. The request includes a parameter that triggers the Xdebug session start, allowing the module to detect if the xdebug.remote_connect_back setting is misconfigured.

The module then applies a series of matching conditions to the response received from the target application. These conditions include checking for the presence of a specific DNS interaction protocol, the presence of a Set-Cookie header containing a randomized XDEBUG_SESSION value, and a successful HTTP status code of 200.

If all the matching conditions are met, the module reports a vulnerability, indicating that the xdebug.remote_connect_back setting is misconfigured and potentially vulnerable to remote code execution attacks.

It is crucial to address this vulnerability by properly configuring the xdebug.remote_connect_back setting and implementing appropriate access controls to prevent unauthorized access and potential exploitation.