VERY IMPORTANT

Mandiant has observed Russian nation-state attackers APT29 employing domain fronting techniques for stealthy backdoor access to victim environments for at least two years. There has been considerable discussion about domain fronting following the release of a paper detailing these techniques. Domain fronting provides outbound network connections that are indistinguishable from legitimate requests for popular websites. APT29 has used The Onion Router (TOR) and the TOR domain fronting plugin meek to create a hidden, encrypted network tunnel that appeared to connect to Google services over TLS. This tunnel provided the attacker remote access to the host system using the Terminal Services (TS), NetBIOS, and Server Message Block (SMB) services, while appearing to be traffic to legitimate websites. The attackers also leveraged a common Windows exploit to access a privileged command shell without authenticating.