North Korea-linked Lazarus APT uses Log4J to target VMware servers

North Korea-linked Lazarus APT is exploiting the Log4J remote code execution (RCE) in attacks aimed at VMware Horizon servers.

North Korea-linked group Lazarus is exploiting the Log4J RCE vulnerability (CVE-2021-44228) to compromise VMware Horizon servers.

Multiple threat actors are exploiting this flaw since January, in January VMware urged customers to patch critical Log4j security vulnerabilities impacting Internet-exposed VMware Horizon servers targeted in ongoing attacks.

Researchers from the Ahnlab ASEC analysis team reported that since April 2022 the Lazarus APT has been exploiting the RCE in attacks against VMware Horizon installs exposed online.

The attack chain starts with the exploitation of the Log4j vulnerability to execute a powershell command on VMware Horizon’s process ‘ws_tomcatservice.exe’. The PowerShell command installs the NukeSped backdoor on the vulnerable server, this backdoor was first analyzed by Fortinet researchers in 2019 that attributed it to the Lazarus APT.

The variant analyzed by the ASEC team is developed with C++, it uses virtual functions and RC4 algorithm for C2 communications.

The NukeSped backdoor can perform keylogging, taking screenshots, and file and shell tasks, the most recent version can dump USB contents and access web camera devices using specific modules.

“The attacker used NukeSped to additionally install infostealer. The 2 malware types discovered are both console types, not saving the leak result in separate files. As such, it is assumed that the attacker remotely controlled the GUI screen of the user PC or leaked data in the pipeline form.” reads the analysis published by the experts.

In some cases, the attackers used exploited the RCE to install the Jin Miner cryptocurrency miner instead of NukeSped.

ASEC researchers published Indicators of Compromise (IoCs) for these attacks.

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Pierluigi Paganini

(SecurityAffairs – hacking, domain name system)

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Pierluigi Paganini

Pierluigi Paganini is member of the ENISA (European Union Agency for Network and Information Security) Threat Landscape Stakeholder Group and Cyber G7 Group, he is also a Security Evangelist, Security Analyst and Freelance Writer. Editor-in-Chief at "Cyber Defense Magazine", Pierluigi is a cyber security expert with over 20 years experience in the field, he is Certified Ethical Hacker at EC Council in London. The passion for writing and a strong belief that security is founded on sharing and awareness led Pierluigi to find the security blog "Security Affairs" recently named a Top National Security Resource for US. Pierluigi is a member of the "The Hacker News" team and he is a writer for some major publications in the field such as Cyber War Zone, ICTTF, Infosec Island, Infosec Institute, The Hacker News Magazine and for many other Security magazines. Author of the Books "The Deep Dark Web" and “Digital Virtual Currency and Bitcoin”.