TOTOLINK A3300R Buffer Overflow Vulnerability in DDNS Configuration Function

A buffer overflow vulnerability has been identified in the TOTOLINK A3300R router, specifically in the firmware version 17.0.0cu.557_B20221024. The issue arises in the 'setDdnsCfg' function within the file '/cgi-bin/cstecgi.cgi'. This vulnerability can be exploited remotely, and a public exploit is available.

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 '/cgi-bin/cstecgi.cgi' endpoint with a crafted 'provider' parameter. This parameter is not properly validated for length, allowing for an overflow when the 'provider' value is read back via the 'getDdnsCfg' function.