The Central Intelligence Agency, which engages in covert activities at the request of the President of the United States, has been the latest victim of notorious hacking group LulzSec.

LulzSec has launched a series of high profile cyber attacks -- and posted evidence of such attacks in its Website -- against Public Broadcasting System, Sony Corp., the U.S. Senate and the Atlanta chapter of InfraGard, an affiliate of the Federal Bureau of Investigation.

Yesterday, at 5:48 p.m., LulzSec, which claims to be "the world's leaders in high-quality entertainment at your expense," posted an alert on Twitter: "Tango down - cia.gov - for the lulz." The site was back up by 8 p.m.

The group, also known as Lulz Security, on Monday cracked the U.S. Senate's website. The hackers said after the attack, "We don't like the US government very much. Their boats are weak, their lulz are low, and their sites aren't very secure. In an attempt to help them fix their issues, we've decided to donate additional lulz in the form of owning them some more!"

Lulz Security posted a configuration file for the Senate's main website. The material in the file suggests sensitive information was not breached, but does indicate Lulz Security infiltrated the Senate's website.

"This is a small, just-for-kicks release of some internal data from Senate.gov," Lulz Security said in a news release. "Is this an act of war, gentlemen?"

LulzSec on June 6 said in that in response to NATO's and U.S. President Barrack Obama's decision to up the stakes with regard to hacking and now treat hacking as "an act of war", the group just hacked Infragard.

The hackers said they leaked Infragard's user base, including the 180 accounts. "Most of them reuse their passwords in other places, which is heavily frowned upon in the FBI/Infragard handbook and generally everywhere else too," the group said.

While many have characterized LulZSec's attacks as pranks rather than serious cyber-warfare, the series of attacks in recent months against businesses, government agencies and media firms have cast a spotlight on the vulnerability of online data.

A report by NATO, a powerful military alliance of countries from North America and Europe, noted that the Internet has made state and society much more vulnerable to attacks such as computer intrusions, scrambling software programs, undetected insiders within computer firewalls, or cyber terrorists.

NATO Parliamentary Assembly General Rapporteur Lord Joplingon the global level, NATO should support initiatives to negotiate at least some international legal ground rules for the cyber domain. He added that NATO should consider applying common funding procedures for procurement of some critical cyber defence capabilities for its member states.