Reputed Iranian threat actor APT33 has been employing more than a dozen secret botnets to infiltrate and spy on the networks of various Middle Eastern, U.S. and Asian organizations, and are even setting up their own VPN networks to conceal their operations, according to researchers.
Trend Micro described these findings in a blog post this week, vaguely identifying some of the infected American entities as a private U.S. company that offers national security services, a victim likely involved with the U.S. military, and victims connecting from a university and a college.
APT33, aka Refined Kitten, is particularly known to target the oil and aviation industries, and is commonly associated with the Shamoon and StoneDrill disk wiper malware programs.
Trend Micro described the botnets as small and elusive, noting that each is made up of a dozen or fewer infected computers used to maintain persistence in highly targeted, compromised networks. The malware running individual bots is mostly limited to downloading and running additional malicious code.
“In fall of 2019 we counted 10 live bot data aggregating and bot controlling servers and tracked a couple of them for months,” states the blog post, written by Trend Micro researchers Feike Hacquebord, Cedric Pernet and Kenney Lu. “These aggregators get data from very few C&C servers (only one or two), with only up to a dozen victims per unique C&C domain.”
Keeping the botnets small is one way to stay under the radar, but APT33 also attempts to be elusive through the command-and-control infrastructure it has established.
“The C&C domains ..