Trend Micro has found traces of APT33 operations lately, according to a report it issued. Among the evident changes in how the threat actor operates, Trend saw in its recent findings that the Iran-linked group has been using about a dozen live Command and Control (C&C) servers for extremely narrow targeting. The malware campaigns were directed against organizations in the Middle East, the US and Asia.
Using many servers in one just one campaign is anomalous. It's noisy, and calls attention to itself. Trend Micro thinks that using this many servers -- organized into a botnet -- is needed to gain persistence after deployment within the networks of selected targets.
Trend found that, "infections in 2019 are two separate locations of a private American company that offers services related to national security, victims connecting from a university and a college in the US, a victim most likely related to the US military, and several victims in the Middle East and Asia."
APT33 has a bad rep in the oil industry, since oil has taken so many hits from it. In the fall of 2018, the group observed communications between a UK-based oil company with computer servers in the UK and India and an APT33 C&C server. Another European oil company suffered from an APT33-related malware infection on one of its servers in India for at least three weeks in November and December 2018. The group also been known to use destructive malware, such as "Shamoon."
Lately, the group has been using its newer servers for botnets, which consist of about 12 members. The domains used for them are usually hosted on cloud hosted proxies. They function as proxies to relay URL requests from the infected bots to backends at shared webservers that can host thousands of legitimate domains. APT33 is hiding its needles in a haystack.
The group is also doing some other kinds of big-time hiding. Trend found that the APT33 folk had built their own virtual private network (VPN). Now, open source software like OpenVPN can make this task less technically challenging but you still need bulletproof hosting. The VPN has exit nodes which are changed frequently. The APT33 group uses these VPN connections to issue commands to the bots as well as collect data from them. It also hides its own IP addresses through their use.
The VPN can do more, though. Trend observed that, "these private VPN exit nodes are also used for reconnaissance of networks that are relevant to the supply chain of the oil industry. More concretely, we have witnessed some of the IP addresses [that they found infected] doing reconnaissance on the network of an oil exploration company and military hospitals in the Middle East, as well as an oil company in the U.S."
The group has used the VPN to visit websites of penetration testing companies, webmail, websites on vulnerabilities, and websites related to cryptocurrencies, as well as to read hacker blogs and forums.
One mitigation might be to check security logs against some of the IP addresses in the report that Trend has found to be infected. The first step in curing a situation is to be aware that it is occurring in the first place.
— Larry Loeb has written for many of the last century's major "dead tree" computer magazines, having been, among other things, a consulting editor for BYTE magazine and senior editor for the launch of WebWeek.