From: Luigi Auriemma (aluigiautistici.org)
Date: Wed Jan 02 2008 - 13:55:57 CST

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                             Luigi Auriemma

Application: Georgia SoftWorks SSH2 Server (GSW_SSHD)
              http://www.georgiasoftworks.com/prod_ssh2/ssh2_server.htm
Versions: <= 7.01.0003
Platforms: Windows
Bugs: A] format string in the log function
              B] buffer-overflow in the log function
              C] buffer-overflow in the handling of the password
Exploitation: remote
Date: 02 Jan 2008
Author: Luigi Auriemma
              e-mail: aluigiautistici.org
              web: aluigi.org

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1) Introduction
2) Bugs
3) The Code
4) Fix

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===============
1) Introduction
===============

GSW_SSHD is a well known commercial SSH server which acts as SSH tunnel
for the telnet server GS_Tnet.exe.

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2) Bugs
=======

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A] format string in the log function
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The logging function used by the server is affected by a format string
vulnerability caused by the usage of vsprintf for building the first
message (like "LoginPassword(%s(%s)[%u])") and the usage of another
vsprintf for building the final log entry.
The bug can be exploitable through the username field.

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B] buffer-overflow in the log function
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A buffer-overflow vulnerability is located in the same logging
function.
It's enough to use an username longer than 10000 chars to exploit the
vulnerability.

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C] buffer-overflow in the handling of the password
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The server is affected also by another buffer-overflow this time
located in the instructions which handle the password supplied by the
client exploitable through a string longer than 800 chars.

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3) The Code
===========

http://aluigi.org/poc/gswsshit.zip

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4) Fix
======

No fix

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---
Luigi Auriemma
http://aluigi.org

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