The open-source Ubuntu project shut down on Saturday five of eight
community-run servers that the group sponsors, after attacks were
detected emanating from the computers.

The Ubuntu project, which manages the popular Linux distribution,
received reports of the attacks on Monday, August 6, and proceeded to
take the servers offline. The servers were running an older version of
the Ubuntu Linux operating system, making several software packages
vulnerable to known flaws.

http://www.securityfocus.com/brief/570