Bit9 hacked five months before detection

Credit:
https://www.bit9.com/
It was five months before the intrusion at Bit9 was detected.
According to research by security blogger Brian Krebs, hackers breached Bit9 in July 2012, yet this was not discovered until January 2013.
After sharing the hashes of the 33 files that hackers had signed with the stolen certificate and searching for them on VirusTotal, the first match turned up a file called ‘media.exe', which was compiled and then signed using Bit9′s certificate on 13 July 2012. The other result was a Microsoft driver file for an SQL database server, which was compiled and signed by Bit9′s certificate on 25th July 2012.