Sunday, May 3, 2009

Grabit <= 1.7.2 beta 3 NZB file parsing stack overflow

I can’t usually find the time for vulnerability research, but a while ago I found a bug in Grabit, a popular usenet client with NZB support. I posted the following message to Bugtraq and Full Disclosure today:

Grabit <= 1.7.2 beta 3 NZB file parsing stack overflow

Impact: Remote code execution
Version: <= 1.7.2 beta 3

Description
Grabit is a popular Windows usenet client designed for downloading binary files. It has support for NZB files, which a user would usually acquire from an external source. Version 1.7.2 beta 3 is vulnerable to a stack overflow when parsing DTD references in NZB files. Earlier versions are vulnerable as well. Reliable exploitation is pretty straightforward.

Fix
I reported this to the author a while ago. He has now released version 1.7.2 beta 4, which fixes the bug. It can be downloaded at http://www.shemes.com/

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