Bit9 Vendor reports discovering malware signed with their own keys. Given that they are an antimalware company, this attack could be a platform for additional higher-level hacks at other companies.

• Krebs On Security: Security Firm Bit9 Hacked, Used to Spread Malware
• Reuters: Hackers breached security firm Bit9, then attacked its customers

Update

Krebs On Security updated their information on this attack to note that it began in July 2012, and that it used similar malware as was seein in targetted attacks on US defense firms.

• Krebs On Security: Bit9 Breach Began in July 2012