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                             Luigi Auriemma

Application:  Halo: Combat Evolved
              http://www.bungie.net/Games/HaloPC/
Versions:     <= 1.4
Platforms:    Windows and MacOS
Bug:          off-by-one (Denial of Service)
Risk:         medium/high
Exploitation: remote, versus server
Date:         09 September 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
===============


Halo is the widely known game originally developed by Bungie Studios
and ported on PC by Gearbox Software (http://www.gearboxsoftware.com).
It has been released in September 2003.


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


Halo uses the Gamespy SDK and moreover the handshake algorithm provided
in this library (http://aluigi.altervista.org/papers/gssdkcr.h) to let
players to join servers.

The off-by-one bug is located just in the client's response (the last
stage of this handshake) because if it is longer than 32 bytes causes
the immediate crash of the server.


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


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


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


Patch 1.05 for both Win32 and MacOS.


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