APT33, the Iran-linked APT group, has been using multiple layers of obfuscation to run a dozen live C2 servers for extremely targeted attacks.

APT33, the Iran-linked APT group, has been using multiple layers of obfuscation to run a dozen live C2 servers involved in extremely targeted malware attacks.

The targeted malware campaigns aimed at organizations in the Middle East, the U.S., and Asia.

The APT33 group has been around since at least 2013, since mid-2016, the group targeted the aviation industry and energy companies with connections to petrochemical production. Most of the targets were in the Middle East, others were in the U.S., South Korean, and Europe.

The nation-state actors are using small botnets composed of up to a dozen infected computers to gain persistence within the target networks.

“The malware is rather basic, and has limited capabilities that include downloading and running additional malware.” reads the analysis published by Trend Micro. “Among active infections in 2019 are two separate locations of a private American company that offers services related to national security, from a university and a college in the U.S., a victim most likely related to the U.S. , and several victims in the Middle East and Asia.”

According to a report published by the experts from Recorder Future in July, Iran-linked cyberespionage group APT33 has updated its infrastructure after the publication of a report detailing its activities.

The APT group recently targeted organizations in the oil and aviation industries, a private American company that offers services related to national security, victims connected to a university and a college in the US, a victim most likely related to the US military, and several entities in the Middle East and Asia.

While investigating the attacks, the experts from Trend Micro collected useful information to understand how APT33 manages its hacking infrastructure.

The command and control infrastructure was layered and isolated to remain under the radar and make harder investigation and takedown from security firms and law enforcement agencies.

The above scheme shows that the APT group leverage a VPN layer build with a custom-built network of VPN nodes, APT33 was operating its own private VPN network.

“Threat actors often use commercial VPN services to hide their whereabouts when administering C&C servers and doing reconnaissance. But besides using VPN services that are available for any user, we also regularly see actors using private VPN networks that they set up for themselves.” continues the post. “APT33 likely uses its VPN exit nodes exclusively. We have been tracking some of the group’s private VPN exit nodes for more than a year and we have listed known associated IP addresses in the table below. “

Trend Micro has been tracking some of the group’s private VPN exit nodes for more than a year, below the list of IP addresses associated with the group’s activity .

IP address First seen Last seen 5.135.120.57 12/4/18 1/24/19 5.135.199.25 3/3/19 3/3/19 31.7.62.48 9/26/18 9/29/18 51.77.11.46 7/1/19 7/2/19 54.36.73.108 7/22/19 10/05/19 54.37.48.172 10/22/19 11/05/19 54.38.124.150 10/28/18 11/17/18 88.150.221.107 9/26/19 11/07/19 91.134.203.59 9/26/18 12/4/18 109.169.89.103 12/2/18 12/14/18 109.200.24.114 11/19/18 12/25/18 137.74.80.220 9/29/18 10/23/18 137.74.157.84 12/18/18 10/21/19 185.122.56.232 9/29/18 11/4/18 185.125.204.57 10/25/18 1/14/19 185.175.138.173 1/19/19 1/22/19 188.165.119.138 10/8/18 11/19/18 193.70.71.112 3/7/19 3/17/19 195.154.41.72 1/13/19 1/20/19 213.32.113.159 6/30/19 9/16/19 216.244.93.137 12/10/18 12/21/18

The private VPN exit nodes were used to send command to the malware as well as for reconnaissance of networks that are relevant to the supply chain of the oil industry and military hospitals in the Middle East.

“APT33 also has a clear interest in websites that specialize in the recruitment of employees in the oil and gas industry,” concludes Trend Micro. “We recommend companies in the oil and gas industry to cross-relate their security log files with the IP addresses listed above.”

Pierluigi Paganini

( SecurityAffairs – APT33, VPN)

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