Pierluigi Paganini February 02, 2021

Ransomware operators are exploiting two VMWare ESXi vulnerabilities, CVE-2019-5544 and CVE-2020-3992, to encrypt virtual hard disks.

Security experts are warning of ransomware attacks exploiting two VMWare ESXi vulnerabilities, CVE-2019-5544 and CVE-2020-3992, to encrypt virtual hard disks.

According to ZDNet, threat actors are using VMWare ESXi exploits to encrypt the disks of virtual machines deployed in enterprise environments.

Since October, the RansomExx Ransomware gang (also known as Defray777) expanded its operations by targeting VMWare virtual machines.

Victims reported that their VMs were abruptly shut down and then all files on the datastore were encrypted (vmdk, vmx, logs). Threat actors left the ransom note at the datastore level.

The news of the attack was also confirmed by the popular cybersecurity researchers Kevin Beaumont that reported that threat actors are using the two issues to bypass all Windows OS security, by shutting down VMs and encrypting the VMDK’s directly on hypervisor.

Both CVE-2019-5544 and CVE-2020-3992 vulnerabilities in VMware ESXi impact the Service Location Protocol (SLP), reside in the OpenSLP open-source implementation of the Service Location Protocol (SLP), which allows the software to locate resources on a network.

The CrowdStrike experts, Sergei Frankoff and Eric Loui, also reported that the Sprite Spider ransomware operators also started targeting ESXi hosts since July 2020. 

ZDNet reported that at the time of this writing only RansomExx ransomware operators are exploiting the above issues, but it is aware that the operators of the Babuk Locker ransomware will implement a similar attack chain.

System administrators are recommended to update their VMWare ESXi installs or disable SLP support to secure them.

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Pierluigi Paganini

(SecurityAffairs – hacking, VMWare ESXi)

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