The hacker group known as LulzSec appears to be back after many months of lying low, saying it has obtained email addresses and other information about nearly 171,000 users of MilitarySingles.com, a commercial dating site.
The group, which in 2011 went after government agencies and companies including the FBI, CIA, Sony and even PBS, said many of the email addresses include @us.army.mil and other addresses reserved for the military.
The website bills itself as "the dating site for single soldiers and those interested in meeting them."
The Pentagon could not be reached for comment.
The programmers of the website are investigating the claimed attack and are taking measures to increase security, said Robert Goebel, chief executive of ESingles Inc., which owns the site.
"Regardless of whether it was a true claim or false claim," he said, "we're treating it as though it's true just to be safe."
But Goebel said he did not think the dating site was actually hacked. He said it was down for some time over the weekend, but that was because of scheduled maintenance. He also said he was not sure how the hackers could have gotten so many accounts when the site has only about 140,000 members.
The LulzSec hackers are "probably trying to make a name for themselves or something," Goebel said. "Just because we have the name 'military' in it, that might be why they decided to claim they went after us."
Goebel said members of the dating site shouldn't panic. Even if the hackers were successful, he said, the site's passwords are encrypted so all accounts are safe.
LulzSec's actions are its first in a while. The group has not posted on its Twitter account since late July, and since then some members of the group have been arrested.
LulzSec began as a group of hackers who were originally part of the decentralized Internet group called Anonymous. The early members of LulzSec said they went after companies and organizations to expose security holes and for the "lulz," slang for kicks and giggles.