On November 25, the US-Computer Emergency Readiness Team issued the following advisory on the Regin Remote Access Trojan.
https://www.us-cert.gov/ncas/alerts/TA14-329A
A definition for this malware has been available for the workstations running Sophos since November 25. Please see the following URLs for additional details.
https://www.sophos.com/en-us/threat-center/threat-analyses/viruses-and-spyware/Troj~Regin-F.aspx
https://www.sophos.com/en-us/threat-center/threat-analyses/viruses-and-spyware/Troj~Regin-I.aspx
http://www.computerworld.com/article/2851060/security0/regin-state-sponsored-malware-itbwcw.html