The U.S. Sergeant at Arms Office confirmed Monday that the Senate's website had been hacked this past weekend and that it has ordered a review of all Senate computer sites.
"Although this intrusion is inconvenient, it does not compromise the security of the Senate's network, its members or staff," a Sergeant at Arms Office official said. "Specifically, there is no individual user account information on the server supporting senate.gov that could have been compromised."
The revelation came after a loosely aligned group of computer hackers calling themselves Lulz Security said they broke into the U.S. Senate's computer network.
Lulz Security, who have hacked into Sony's website and the U.S. Public Broadcasting System, posted online a list of files that appear not to be sensitive but indicate the hackers had been into the Senate's computer network.
"We don't like the US government very much," Lulz Security said at the top of their release. "This is a small, just-for-kicks release of some internal data from Senate.gov - is this an act of war, gentlemen? Problem?"
The comment refers to reports that the U.S. military had decided that it could respond to cyber attacks from foreign countries with traditional military force.
Senate staffers asked about the hack were unaware of it.
"They certainly demonstrated that they were in and they found the file server," said Stewart Baker, a former cyber official at the Department of Homeland Security.
"It's not clear from the file names that there's anything sensitive here. The hackers may have done the equivalent of burglarizing the Senate and bragging because they managed to steal a bunch of souvenirs from the gift shop," said Baker, now a partner at Steptoe and Johnson LLP.
John Bumgarner, of the private, non-profit U.S. Cyber Consequences Unit, said the break-in would cause red faces at the Senate.
"They're all valid directories," he said after looking at data posted online. "It's very embarrassing that this happened that this was a government site that belonged to the Senate and was compromised."
"They probably also got user names and passwords," he said.
The group has also hit websites owned by Sony Corp. and Nintendo. It has also claimed credit for breaking into a Fox.com website and publishing data about contestants for the upcoming Fox TV talent show, "X Factor." Fox is a unit of News Corp.
Lulz is a reference to Internet-speak for "laugh out loud."