QuakeWorld Connect Buffer Overflow Vulnerability

The exists a buffer overflow in the initial 'connect' sequence of QuakeWorld.

The first client to server packet provides the user name, colors, and other parameters. The packet is composed of four 0xFF bytes followed by a string such as 'connect "\name\Sucker\key\data"'.

There is no bounds checking on the data from this initial connection packet. A packet with the initial four 0xFF bytes followed by "connect "\x\xxxxxxxxxx'" where 'x' is repeated more than 1024 times will crash the server.

The static buffer being smashed is "con_token" which is 1024 bytes long. The overflow overwrites the structure "mainzone" past this buffer. This causes the server to die while trying to dereference a pointer in this structure from within the function "Z_CheckHeap()".


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