Cybersecurity Briefing — ESXiArgs ransomware targets unpatched VMware ESXi
A widespread ESXiArgs ransomware wave began 3 February 2023, exploiting unpatched VMware ESXi servers via CVE-2021-21974 to encrypt VMs, prompting CISA/FBI mitigation guidance and emergency patching efforts.
Starting 3 February 2023, threat actors mass-exploited CVE-2021-21974 in end-of-life or unpatched VMware ESXi hypervisors, deploying the ESXiArgs ransomware variant and encrypting virtual machine files. Thousands of servers worldwide were impacted due to exposed OpenSLP services.
CISA, FBI, and CERT-FR urged operators to patch or upgrade affected ESXi versions, disable the SLP service, and apply recovery scripts to reconstruct VM metadata where possible. Organizations were advised to validate perimeter exposure of management interfaces and review backup resilience for virtualization hosts.
- CISA alert summarizes exploit vectors, mitigations, and detection steps for ESXiArgs.
- CERT-FR advisory documents initial wave activity on 3 February 2023 and recommends disabling SLP pending patching.
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