GeoVision GV-VMS V20 WebCam Server Login stack overflow vulnerability

Summary

A stack overflow vulnerability exists in the WebCam Server Login functionality of GeoVision GV-VMS V20 20.0.2. A specially crafted HTTP request can lead to an arbitrary code execution. An attacker can make an unauthenticated HTTP request to trigger this vulnerability. #### Stack-overflow via unconstrained sscanf The call to `sscanf` at [1] to split the `Buffer` variable into the `username` and `password` variables doesn't limit the size of the extracted content to match the destination buffers' sizes. In this case, if either the username or password decoded from the authorization string exceeds `40` characters (the size the stack variables `username` and `password`) then a stack overflow will occur. The data is controlled by an attacker, but sronger constraints (e.g. no null bytes) may make exploitation harder. A successful attack could lead to full code execution as SYSTEM on the machine running the service.