The backdoored source code of Unreal IRCD was not spotted for 7 months:
We found out that the Unreal3.2.8.1.tar.gz file on our mirrors has been replaced quite a while ago with a version with a backdoor (trojan) in it. This backdoor allows a person to execute ANY command with the privileges of the user running the ircd. The backdoor can be executed regardless of any user restrictions (so even if you have passworded server or hub that doesn’t allow any users in).