The US Federal Reserve has admitted that hackers were able to breach one of its websites on Sunday, almost certainly the source for 4,000 bank executive logins leaked by Anonymous on the same day.
Although the reported admission steered clear of The organisation said that no critical systems were affected by the attack which it said was caused by an unspecified software flaw.
"The Federal Reserve system is aware that information was obtained by exploiting a temporary vulnerability in a website vendor product," a source told news agencies, connecting the attack to Anonymous in all but name.
"Exposure was fixed shortly after discovery and is no longer an issue. This incident did not affect critical operations of the Federal Reserve system."
Anonymous announced on its Twitter feed that it had posted the logins and other personal such as phone numbers on Sunday as part of 'Operation Last Resort' designed as retaliation for the legal pursuit of Internet campaigner Aaron Swartz, who committed suicide on 11 January.
Timed to coincide with the US Super Bowl, data taken during the Anonymous attack was posted to several websites, including the Alabama Criminal Justice Information Center, from where it was eventually taken down.
"Whether Anonymous have managed to obtain usernames, passwords and other sensitive information is worrying, but what is more concerning is the fact that the Federal Reserve was breached in the first place," said Marty Meyer, president of security vendor, Corero Network Security.
"No matter how the attackers managed to access their networks, it goes a long way to demonstrate that no organisation is vulnerable from attack. With the right skills and enough motivation, any organisation can fall victim to an attack from cyber-criminals," he said.