Amid the real world protests swarming around Wall Street, the Department of Homeland Security has warned financial companies to be vigilant against a looming cyber- security threat from Anonymous, a headless horde of activist hackers.

Wanted for shutting down Web sites as high-profile as that of the CIA, a recently released DHS bulletin said the group “will continue to exploit vulnerable publicly available Web servers, computer networks and other digital information mediums for the foreseeable future.”

While the DHS warning doesn’t mention Wall Street protests in particular, it did say that “publicized events” like Occupy Wall Street may motivate the group.

Nevertheless, the agency wouldn’t weigh in on the ways it might monitor Anonymous’s involvement in Occupy Wall Street.

“We don’t have any role in someone’s right to public protest,” said a DHS official.

Occupy Wall Street spokesman Patrick Bruener acknowledged that Anonymous marches alongside those demonstrating against the financial industry’s misdeeds but said that sometimes their actions cross a line.

“Anonymous stands in solidarity with us, and they’re nonviolent. They have legitimate grievances — they have reasons to be upset with the way the Internet works — but sometimes the way they put that out there isn’t beneficial,” Bruener said.

So far, Anonymous’s international legion of irate computer whizzes has done the most damage by exposing on the Internet data held in corporate computers. In July, an Anonymous hacker allegedly broke into Monsanto’s computers and released personal information of 2,500 employees, the bulletin states.

Anonymous’s greatest strength is numbers.

“One baseball thrown at an armored car won’t do much damage, but 50,000 baseballs all at once can bury it,” said Thomas Wilson, a Web technician who works with corporate computer systems, adding that companies sometimes sacrifice security for their bottom line.