According to a report by the Washington Post, roughly 3,800 customer credit-card numbers were taken in the attack and officials are working with the U.S. Secret Service to investigate the crime.
Executives at the security company declined to talk to internetnews.com about the network break-in because of the ongoing investigation.
The breach is a black eye for a company providing software that tracks down and collects information on network breaches. Guidance Software's EnCase product is used by law enforcement agencies, government investigators and Fortune 1000 companies to track down and investigate digital break-ins, as well as perform network and software audits.
According to a post at the Forensicfocus.com discussion forum, Guidance Software officials discovered hackers got past the company's perimeter defenses and accessed one of its servers and its electronic records in November.
The post, which referenced a notice purportedly from an administrator on Guidance Software's members-only discussion board, said the company discovered the breach Dec. 7 and shored up the weakness that allowed the attacker to compromise their defenses.
"Although this event is extremely troubling, we are confident, based on an immediate forensic analysis, that the intrusion has now been effectively terminated and our network has been secured," the administrator's note stated.