Researchers at the Positive Technologies Expert Security Center (PT ESC) have identified a new, previously unknown APT group that has systematically attacked mainly Russia’s fuel and energy complex and aviation industry. The PT ESC incident response team discovered the existence of ChamelGang while investigating security vulnerabilities in the Russian fuel/energy and aviation production sectors. 

The group, known as ChamelGang, appears to be focused on stealing data from compromised networks, and its first trusted relationship attacks were registered in March 2021. Similarly, this group has also targeted institutions and government servers in nine other countries, including the United States, India, Nepal, Taiwan and Japan. Since the group has started exploiting ProxyShell vulnerabilities in attacks to infect Microsoft Exchange, it’s possible that vulnerable servers in the U.K. could be affected in the future as well.

The group was named ChamelGang (from chameleon) for using plausible phishing domains and features of operating systems to mask malware and network infrastructure. For example, attackers register phishing domains that imitate legitimate services of large international companies, such as Microsoft, TrendMicro, McAfee, IBM and Google, including their support services, content delivery and updates. While studying the group’s activity, PT ESC specialists found domains,,,, and The APT group also placed SSL certificates on its servers that imitated legitimate ones (,,, and

Denis Kuvshinov, Head of Threat Analysis at Positive Technologies, explains: “Targeting the fuel and energy complex and aviation industry in Russia isn’t unique — this sector is one of the three most frequently attacked. However, the consequences are serious: Most often, such attacks lead to financial or data loss — in 84% of all cases last year, the attacks were specifically created to steal data, and that causes major financial and reputational damage. Also, industrial companies often can’t detect a targeted cyberattack on their own — they believe their defenses are strong and that such disruptions are highly unlikely. But in practice, attackers can penetrate the corporate network of an industrial enterprise more than 90% of the time, and almost every such invasion leads to complete loss of control over the infrastructure. More than half of these attacks lead to the theft of data on company partners and employees, mail correspondence, and internal documentation.” 

The research team found that to gain access to the target enterprise’s network, ChamelGang had compromised a subsidiary organization using a vulnerable version of a web application on the open-source JBoss Application Server platform. By exploiting vulnerability CVE-2017-12149 (which had been fixed by RedHat more than four years ago), the criminals could remotely execute commands on the node. Two weeks later, which represents a relatively short time in this dynamic, the group compromised the parent company. The attackers obtained the dictionary password of the local administrator on one of the servers in an isolated segment and penetrated the network via the Remote Desktop Protocol (RDP). The attackers remained unnoticed in the corporate network for three months; after examining it, they gained control over most of it, including critical servers and nodes in different segments. The investigation reveals that the APT group was specifically pursuing data and succeeded in stealing it. 

In the second case revealed by PT ESC, the attackers exploited a chain of related vulnerabilities in Microsoft Exchange (CVE-2021-34473, CVE-2021-34523, CVE-2021-31207), or ProxyShell. This became public last month, and ever since, other APT groups have actively exploited it. The attackers gained access to the company’s mail servers using a backdoor that most antivirus tools had not detected at the attack. As in the first case, the criminals were after sensitive data, but the detection of the APT group and active countermeasures prevented severe theft. The attackers were inside the target organization’s infrastructure for only eight days and didn’t have the time to cause much harm.

One distinctive feature of ChamelGang’s attacks is using new malware: ProxyT, BeaconLoader, and the DoorMe backdoor, which were not previously known. The latter is a passive backdoor, which significantly complicates its detection. The group also uses better-known variants such as FRP, Cobalt Strike Beacon, and Tiny shell.

Denis Goydenko, Head of Information Security Threat Response at Positive Technologies, says, “Among the malware samples we found, the most interesting is the DoorMe backdoor. This is a native IIS module that is registered as a filter through which HTTP requests and responses are processed. Its principle of operation is unusual: the backdoor processes only those requests in which the correct cookie parameter is set. At the time of the incident investigation, DoorMe was not detected by antivirus tools, and although the technique of installing this backdoor is known, we haven’t seen its use in recent times. The backdoor gives attackers wide opportunities in the captured systems: it can execute commands by using cmd.exe and creating a new process, write files in two ways, and copy timestamps. In total, six different commands have been implemented.”