Security researchers investigating a set of ransomware incidents at multiple companies discovered malware indicating that the attacks may be the work of a hacker group believed to operate on behalf of China.
Although the attacks lack the sophistication normally seen with advanced threat actors, there is strong evidence linking them to APT27, a group normally involved in cyber espionage campaigns, also known as TG-3390, Emissary Panda, BRONZE UNION, Iron Tiger, and LuckyMouse.
Abusing Windows BitLocker
The attacks happened in 2020 and directly targeted at least five companies in the online gambling sector that operate globally and successfully encrypted several core servers.
While these were ransomware incidents in earnest, the threat actor relied on BitLocker, the drive encryption tool in Windows, to lock the servers.
The researchers from cybersecurity firms Profero and Security Joes responded to these incidents and found that the hackers reached their targets through a third-party service provider, which had been infected through another third-party provider.
Analyzing the attacks revealed malware samples linked to DRBControl, a campaign described earlier this year in a report from Trend Micro and attributed to APT27 and Winnti, both groups active since at least 2010 and associate with Chinese hackers. If APT27 focuses on cyberespionage, Winnti is known for its financial motivation.