LockBit affiliates compromise Microsoft Exchange servers to deploy ransomware

Lockbit ransomware affiliates are compromising Microsoft Exchange servers to deploy their ransomware, experts warn.

South-Korean cybersecurity firm AhnLab reported that Lockbit ransomware affiliates are distributing their malware via compromised Microsoft Exchange servers.

In July 2022, two servers operated by a customer of the security firm were infected with LockBit 3.0 ransomware.

Threat actors initially deployed web shell on a compromised Exchange server, then it took just 7 days to escalate privileges to Active Directory admin and stole roughly 1.3 TB of data before encrypting systems hosted in the network.

According to the researchers, the attackers allegedly exploited a zero-day vulnerability in Microsoft Exchange Server.

“Looking at the Microsoft Exchange Server vulnerability history, the remote code execution vulnerability was disclosed on December 16, 2021 (CVE-2022-21969), the privilege escalation vulnerability was disclosed in February 2022, and the most recent vulnerability was on June 27. Information Disclosure Vulnerability vulnerability. That is, among the vulnerabilities disclosed after May, there were no reports of vulnerabilities related to remote commands or file creation.” reads the report published by AhnLab. “Therefore, considering that WebShell was created on July 21, it is expected that the attacker used an undisclosed zero-day vulnerability.

The experts argued that the attackers likely did not exploit recently disclosed CVE-2022-41040 and CVE-2022-41082 vulnerabilities.

Some prominent experts, including the popular Kevin Beaumont said that he is not convinced it’s a zero-day.

The vulnerability researcher Will Dormann pointed out that the report doesn’t include evidence of exploiting of a new zero-day vulnerability.

Bleeping Computer pointed out that at least three vulnerabilities in Microsoft Exchange, discovered by Zero Day Initiative vulnerability researcher Piotr Bazydlo, have yet to be patched.

The three issues, tracked by ZDI as ZDI-CAN-18881, ZDI-CAN-18882, and ZDI-CAN-18932, were reported on September 20, 2022.

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Pierluigi Paganini

(SecurityAffairs – hacking, Lockbit)

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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”.