Doki Linux Malware Infected Docker Servers in the Cloud

Linux offers great applications for personal and small business financial management making it a widely used OS, which also means notorious network infiltrators have their prying eyes on it. In one of the longest ongoing attack campaigns, hackers designed new tools and techniques specifically to tamper with Linux infrastructure.


Ngrok mining botnet campaign with Doki malware

In July, Intezer researchers detected an attack that involved a completely undetected Linux malware and a previously undocumented technique, using a blockchain wallet for generating C&C domain names.
  • An active Ngrok mining botnet campaign, active for at least two years, has been targeting exposed Docker servers in AWS, Azure, and other cloud platforms.
  • The campaign is also deploying a fully undetected backdoor named Doki. The multi-threaded Doki malware is different from the standard cryptominers typically deployed in this attack.
  • The campaign has primarily focused on taking control over misconfigured Docker servers and exploited them to set up their own malicious containers with cryptominers running on the victims' infrastructure.


Malware capabilities

Doki malware has managed to stay undetected for over six months from any of the 60 malware detection engines in VirusTotal, in spite of first being observed on January 14, 2020.
  • The malware uses a scanning tool, such as zmap, zgrap, and jq, to scan the network for ports associated with Redis, Docker, SSH, and HTTP in compromised systems.
  • To dynamically generate its C2 domain in real-time, Doki uses the DynDNS service and a unique Domain Generation Algorithm (DGA) based on the Dogecoin cryptocurrency blockchain.

Recent attacks on Ngrok server

This year in February, scammers were seen using a local web-server exposed to the Internet via the free Ngrok service to collect the stolen data but pretended to be CDNs to hide their tracks.

Closing lines

The bottom line is that cybercriminals are continuously evolving their techniques to evade detection and propagate their attack campaigns through innovative command and control channels. The malicious use of blockchain technlogy in the Doki malware is yet another technique of this kind that make its hard for security teams to detect it. With relevant analysis and intel insights, security teams can devise innnoative methods to thwart such threats.