Cyber-spies are increasingly attempting to hide their command and control operations in plain sight by burying their command infrastructure in the forums of internet heavyweights, including Microsoft.
FireEye and Microsoft have successfully shut down the Chinese threat actor APT17’s use of the MSFT TechNet blog to hide their hacking operations. State-sponsored hackers were posting comments on TechNet in order to embed encoded commands that only their malware could use.
APT17, a China-based advanced persistent threat group, posted in forum threads and created profile pages to host encoded C2 IP addresses that would direct a variant of the BLACKCOFFEE backdoor to their C2 server. TechNet’s security was not compromised by this tactic, which could also work on other forums and boards.
Most threat actors choose to compromise or hijack easily manipulated websites to host command and control nodes, which is a very noisy tactic that allows for quick detection of their location. APT17’s tactics of embedding phone home instructions on Microsoft’s forums are more subtle, but not unprecedented in the wider field of botnet communications. For example, some zombie networks have previously made use of Twitter profiles as a communication channel. APT17 had been observed using popular search engines including Google and Bing to hide their activities and host locations from security researchers.
“This latest tactic by APT17 of using websites’ legitimate functionalities to conduct their communications shows just how difficult it is for organisations to detect and prevent advanced threats,” said Laura Galante, manager, threat intelligence, FireEye. “Given its effectiveness, we anticipate that this encoding and obfuscation will become a truly pervasive tactic adopted by threat actors around the world.”
APT17 predominantly targets US government entities, the defence industry, law firms, information technology companies, mining companies, and non-governmental organisations. FireEye reckons the group is sponsored by the Chinese government.