Security firm Bit9 has blamed a breach of its own systems for an attack which left customers vulnerable to malware infections.
The company on Friday admitted that its own systems had been compromised and used to create a set of false security clearances which allowed attackers to bypass the Bit9 Application Whitelisting security tools.
According to Bit9, systems on the company's network had beeb breach by hackers, allowing them to classify their own malware payloads as permitted applications on the Bit9 platform.
The attackers were then able to install the malware on the networks of third-party firms without triggering the Bit9 protections.
"Due to an operational oversight within Bit9, we failed to install our own product on a handful of computers within our network," Bit9 chief executive Patrick Morley said in a company blog post on the matter.
"As a result, a malicious third party was able to illegally gain temporary access to one of our digital code-signing certificates that they then used to illegitimately sign malware."
Morley said that only a few customers were subject to the attack, the company has since remedied the issue and revoked the phoney certificates.
Security researcher Brian Krebs, who first broke word of the attack, noted that the incident was particularly painful for Bit9 given the company's emphasis on application whitelisting as a means for securing networks.
"There may be deep irony in this attack," Krebs wrote.
"While Bit9 has made a name for itself based on the reality that antivirus software cannot keep up with the tens of thousands of new malware variants being unleashed on the internet each day... there is a better than even chance that the malware signed with Bit9′s keys was first detected with traditional antivirus products."