It is now being widely reported that a member of a notorious hacking group has released sensitive personal information four months after compromising a major data broker.

The group, USDoD, claimed it stole over 2.9 billion records of personal information from Americans, including their Social Security numbers and physical addresses.

The breach, which includes Social Security numbers and other sensitive data, could power a raft of identity theft, fraud and other crimes, said Teresa Murray, consumer watchdog director for the U.S. Public Information Research Group.

“If this in fact is pretty much the whole dossier on all of us, it certainly is much more concerning” than prior breaches, Murray said in an interview. “And if people weren’t taking precautions in the past, which they should have been doing, this should be a five-alarm wake-up call for them.”