D-Link DIR-632 Stack-Based Buffer Overflow Vulnerability in HTTP POST Request Handler

A critical stack-based buffer overflow vulnerability has been identified in the D-Link DIR-632 router, specifically in the firmware version FW103B08. The issue arises in the 'get_pure_content' function of the HTTP POST request handler, where the 'Content-Length' argument is not properly validated. This vulnerability can be exploited remotely by sending a specially crafted POST request, and it affects devices that are no longer supported by the manufacturer.

Impact

Exploitation of this vulnerability leads to a stack-based buffer overflow, which can commonly result in arbitrary code execution or causing the device to crash.

Reproduction

The vulnerability can be reproduced by sending a POST request to the router with a crafted 'Content-Length' header. If the 'Content-Length' is set to a negative value, it will be interpreted as a large unsigned integer, causing an overflow when the data is read. This overflow can then be exploited to execute arbitrary code.