Linux-based ransomware found targeting VMWare ESXi Servers


The Sonicwall Capture Labs threat research team has come across a linux variant of a ransomware early on this week. Avoslocker is another ransomware-as-a-service (RaaS) selling their ready-made ransomware to affiliates to carry out ransomware attacks. This linux variant was specifically made to target VMWare ESXi servers that more and more companies are switching their servers on to for easier management. It is a very valuable target for cybercriminals since one ESXi server can host multiple virtual machines and therefore host many critical services for a company.

Infection Cycle:

This variant comes as an ELF executable file. Upon manually running it, the user is presented with the following use options.

Once installed, Avoslocker will run the following command to power off all running virtual machines within an ESXi host.

esxcli –formatter=csv –format-param=fields==”WorldID,DisplayName” vm process list | tail -n +2 | awk -F $’,’ ‘{system(“esxcli vm process kill –type=force –world-id=” $1)}’

It appends “.avoslinux” extension to all encrypted files.

It also leaves a ransom note reminding victims to avoid shutting down their system to prevent any files being permanently damaged.

They provide a link to a website only accessible via a tor browser for further details on how to pay and retrieve encrypted files.

SonicWall Capture Labs provides protection against this threat via the following signature:

  • GAV: Avoslocker.RSM (Trojan)

This threat is also detected by SonicWALL Capture ATP w/RTDMI and the Capture Client endpoint solutions.

Security News
The SonicWall Capture Labs Threat Research Team gathers, analyzes and vets cross-vector threat information from the SonicWall Capture Threat network, consisting of global devices and resources, including more than 1 million security sensors in nearly 200 countries and territories. The research team identifies, analyzes, and mitigates critical vulnerabilities and malware daily through in-depth research, which drives protection for all SonicWall customers. In addition to safeguarding networks globally, the research team supports the larger threat intelligence community by releasing weekly deep technical analyses of the most critical threats to small businesses, providing critical knowledge that defenders need to protect their networks.