Security News > 2022 > October > Microsoft Exchange servers hacked to deploy LockBit ransomware

Lockbit ransomware affiliates are encrypting victims via Microsoft Exchange servers hacked using exploits targeting unpatched vulnerabilities.

In at least one such incident from July 2022, the attackers used a previously deployed web shell on a compromised Exchange server to escalate privileges to Active Directory admin, steal roughly 1.3 TB of data, and encrypt network systems.

AhnLab says the Exchange servers were likely hacked using an "Undisclosed zero-day vulnerability," given that the victim received technical support from Microsoft to deploy quarterly security patches after a previous compromise from December 2021.

While Microsoft is currently working on security patches to address two actively exploited Microsoft Exchange zero-days tracked as CVE-2022-41040 and CVE-2022-41082, AhnLab added that the one used to gain access to the Exchange server in July might be different since attack tactics don't overlap.

"There is a possibility that the vulnerabilities of Microsoft Exchange Server disclosed by GTSC, a Vietnamese security company, on September 28 were used, but the attack method, the generated WebShell file name, and subsequent attacks after WebShell creation," AhnLab says.

Although differences in the delivery method can't be considered enough evidence the attackers used a new zero-day and security experts are also not convinced this is the case, at least one more security vendor knows of three other undisclosed Exchange flaws and provides "Vaccines" to block exploitation attempts.

News URL

https://www.bleepingcomputer.com/news/security/microsoft-exchange-servers-hacked-to-deploy-lockbit-ransomware/