In a Friday blog post, security firm Bit9 confirmed that hackers had attacked the company's computer systems, and had used its own software for further spreading malware.

With Krebs on Security's Brian Krebs first reporting the hack of Bit9 systems, it was revealed that, with a number of malware pieces showing Bit9's own encryption keys, it was evident that the security firm - which validates the safety of software - was a vector for the distribution of malware.

In a confirmation of Krebs report about the hack, Bit9 said in the blog post that the hacking incident was essentially the outcome of the fact that the company had not locked down its own computer systems; and not because there was a flaw in its software

Noting that "due to an operational oversight within Bit9, we failed to install our own product on a handful of computers within our network," Bit9 CEO Patrick Morley said the oversight had apparently given the leverage to a malicious third party "to illegally gain temporary access to one of our digital code-signing certificates that they then used to illegitimately sign malware."

Moreover, revealing that the issue has now been resolved, Bit9 said that the malware attack, resulting from the company's seal of approval, had affected only three of its customers.