In-game format string in Judge Dredd vs. Death 1.01

[Luigi Auriemma <aluigi@xxxxxxxxxxxxx>]

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                             Luigi Auriemma

Application:  Judge Dredd: Dredd vs. Death
              http://www.dreddvsdeath.com
Versions:     <= 1.01
Platforms:    Windows
Bug:          format string
Exploitation: remote, versus server (in-game)
Date:         02 October 2004
Author:       Luigi Auriemma
              e-mail: aluigi@xxxxxxxxxxxxxx
              web:    http://aluigi.altervista.org


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


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


Dredd vs Death is a cool FPS game based on the homonym comic strip.
The game has been developed by Rebellion (http://www.rebellion.co.uk)
and has been released in October 2003.


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2) Bug
======


The problem is a format string bug in the handling of the messages
received from clients like "player connected", chat messages and so on.

Like any in-game bug, the attacker must have access to the match (so if
the server is protected by password, he must know it).


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


Launch a client and a server, go on the client side, join the server
and send the following chat message (by default pressing the 'T' key):

  %n%n%n%n%n

The server will crash immediately.

You can do the same check running only the server and sending the chat
message from the same computer.


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4) Fix
======


No fix.
Developers have not replied to my mails.


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