Date Published: 16th October 2000
Advisory ID: N/A
Bugtraq ID: 1799
CVE CAN: N/A
Title: Half-Life Dedicated Server Vulnerability
Class: Buffer Overflow
Remotely Exploitable: Yes
Locally Exploitable: Yes
Release Mode: FORCED RELEASE
This vulnerability is actively being exploited in the wild.
Half-Life Dedicated Server for Linux 126.96.36.199 & Previous
A buffer overflow vulnerability was discovered in a Half-Life dedicated server during a routine security audit. A user shell was found running on the ingreslock port of the server which lead to an investigation into how this had been achieved. - From the logs left on the server, it was ascertained that a predefined exploit script was used and that the perpetrator failed to further compromise the server due to the Half-Life software running as a non-priveledged user.
The vulnerability appears to exist in the changelevel rcon command and does not require a valid rcon password. The overflow appears to exist after the logging function as the following was found in the last entries of the daemon's logs:-
# tail server.log.crash | strings
L 08/23/2000 - 23:28:59: "[CiC]Foxdie<266>" say "how so?"
Bad Rcon from x.x.x.x:4818:
rcon werd changelevel
rcon werd changelevel
The actual raw exploit code is logged, along with what appears to be the script authors, ADM ( http://adm.freelsd.net/ADM/ ). If they could shed some light on this?
Valve Software promised a patch which has yet to appear. Interim measures would include:-
A) Consider not running the HalfLife software at all!
B) Remove the world execute bit from inetd to 'break' the exploit code - this would only stop the script kiddies
C) Ensure sane ipfwadm/ipchains filters are inplace
Vendor notified on: 14th September 2000
Credit for the vulnerability discovery presumably lies with ADM. :) The forensic work which discovered this problem was performed by Mark Cooper.
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Try http://adm.freelsd.net/ADM/ ?
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