A security issue and a vulnerability have been reported in UnrealIRCd, which can be exploited by malicious people to cause a DoS (Denial of Service) or compromise a vulnerable system.

1) The security issue is caused due to certain files being distributed via e.g. the project's mirrors containing a backdoor. This can be exploited to e.g. execute arbitrary shell commands by sending specially crafted packets to the service.

Note: The backdoor is reported in the source code file of version 3.2.8.1 (e.g. "Unreal3.2.8.1.tar.gz") with an MD5 checksum of 752e46f2d873c1679fa99de3f52a274d. The MD5 checksum of legitimate copies is 7b741e94e867c0a7370553fd01506c66.

2) A boundary error in the user authentication can be exploited to cause a buffer overflow via an overly long username.

Successful exploitation of this vulnerability requires that "allow::options::noident" is used (not used by default).

Solution
Ensure that you've installed a legitimate copy of UnrealIRCd version 3.2.8.1. Please see the vendor's advisories for additional details.

Provided and/or discovered by
Reported by the vendor.

Changelog
Further details available to Secunia VIM customers

Original Advisory
http://www.unrealircd.com/txt/unrealsecadvisory.20090413.txt
http://www.unrealircd.com/txt/unrealsecadvisory.20100612.txt

Deep Links
Links available to Secunia VIM customers