Pierluigi Paganini June 24, 2024

The cybercrime group ExCobalt targeted Russian organizations in multiple sectors with a previously unknown backdoor known as GoRed.

Positive Technologies researchers reported that a cybercrime gang called ExCobalt targeted Russian organizations in multiple sectors with a previously unknown Golang-based backdoor known as GoRed.

Members of the ExCobalt group have been active since at least 2016, the researchers believe that the group is linked to the notorious Cobalt Gang.

Over the past year, ExCobalt targeted Russian organizations in the the following industries:

• Metallurgy
• Telecommunications
• Mining
• Information technology
• Government
• Software development

The Cobalt’s hallmark was the use of the CobInt tool, the same tool that ExCobalt began using in 2022.

While investigating a security incident from March 2024 on a client’s Linux host, Positive Technologies researchers discovered a file named “scrond.” The file was compressed with UPX and upon unpacking it, the experts found included package paths indicating it was likely a proprietary tool named GoRed, associated with a Red Team.

The GoRed backdoor supports several notable features. It allows operators to connect and execute commands, similar to other Command and Control (C2) frameworks such as Cobalt Strike or Sliver. The communication between GoRed and its C2 server relies on the RPC protocol. For secure communication, operators employ DNS/ICMP tunneling, WSS, and QUIC protocols.

GoRed is capable of obtaining credentials from compromised systems and collecting various types of system information, including active processes, host names, network interfaces, and file system structures. To backdoor supports several commands to conduct reconnaissance on a target’s network. The backdoor serializes, encrypts, archives, and sends the collected data to a designated server that stores compromised data.

ExCobalt gained initial access to target entities by taking advantage of a previously compromised contractor. ExCobalt conducted a supply chain attack by infecting a component used to build the target company’s legitimate software

ExCobalt used the Spark RAT to execute commands and multiple tools ad part of the attack chain, including Mimikatz, ProcDump, SMBExec, Metasploit, and rsocx.

The group exploited the following vulnerabilities for privilege escalation: CVE-2022-2586, CVE-2021-3156, CVE-2021-4034, CVE-2019-13272, CVE-2022-27228, CVE-2021-44228, CVE-2021-40438, CVE-2023-3519, BDU:2023-05857, and CVE-2019-12725.

“ExCobalt continues to demonstrate a high level of activity and determination in attacking Russian companies, constantly adding new tools to its arsenal and improving its techniques. Not only is it developing new attack methods, but it’s also actively improving its existing tools, such as the GoRed backdoor.” concludes the report.

“ExCobalt is apparently aiming for more sophisticated and productive methods of hacking and cyberespionage, seeing how GoRed has been acquiring new capabilities and features. These include expanded functionality for collecting victim data and increased secrecy both inside the infected system and in communications with C2 servers.”

Pierluigi Paganini

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