Broadcast forced exit in Ground Control II 1.0.0.7

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                             Luigi Auriemma

Application:  Ground Control II: Operation Exodus
              http://www.groundcontrol2.com
Versions:     <= 1.0.0.7
Platforms:    Windows
Bug:          forced exit (DoS)
Risk:         high
Exploitation: remote, versus servers and clients (broadcast)
Date:         26 August 2004
Author:       Luigi Auriemma
              e-mail: aluigi@altervista.org
              web:    http://aluigi.altervista.org


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


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


Ground Control II is a futuristic strategy game developed by Massive
Entertainment (http://www.massive.se) and released in June 2004.


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2) Bug
======


The problem is very simple, the game automatically exits if it receives
a packet bigger than the max supported size (usually 512 bytes) because
some instructions check for the socket error "Message too long" and
consider it critical.

Both servers and clients are vulnerables and the major problem is just
for clients because a single malicious server is able to automatically
(or also directly) crash any client in the world so nobody can play
online.


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


http://aluigi.altervista.org/poc/gc2boom.zip


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======
4) Fix
======


The official online Massive Entertainment servers have been fixed but
no official patch has been released yet.

The bug is very easy to fix so I have created an unofficial patch for
the dedicated server 1.0.0.7 and the demo 0.0.8.1 (the retail game uses
CD protections so I don't support it):

  http://aluigi.altervista.org/patches/gc2ds-1007-fix.zip
  http://aluigi.altervista.org/patches/gc2-demo0081-fix.zip


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