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                             Luigi Auriemma

Application:  Battlefield 1942 and Vietnam
              http://www.battlefield1942.com
Versions:     Battlefield 1942    <= 1.6.19
              Battlefield Vietnam <= 1.2
Platforms:    Windows and Mac
Bug:          client crash
Exploitation: remote, versus clients (broadcast)
Date:         07 December 2004
Author:       Luigi Auriemma
              e-mail: aluigi@autistici.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
===============


Battlefield 1942 and Vietnam are two of the most known and played FPS
games based on the relative military conflicts.
They are developed by Digital Illusions (http://www.dice.se) and have
been released respectively at September 2002 and March 2004.


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======
2) Bug
======


Like any multiplayer game, Battlefield contacts a master server to know
all the available online servers and then automatically queries them
to collect informations in the in-game browser.

The problem is in the parameter "numplayers" of the server's reply that
if is a too big number causes an immediate freeze of the client
followed (after some seconds) by a crash caused by the access to a NULL
pointer.

This is a broadcast client crash so a single attacker visible in the
master server list is able to passively exploit the bug versus any
vulnerable client online.


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


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


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


Battlefield 1942    1.61b
Battlefield Vietnam 1.21

Note: this patch for Battlefield 1942 corrects, finally, also the known
      bug in the old Gamespy cd-key SDK (aka gshboom, 24 February 2004)
      used by the game and affecting the servers.


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