AntiVM checks for VMWare

Hunt Hypothesis

The detection rule identifies potential adversary behavior through anti-VM checks targeting VMware environments, which may indicate the presence of malware designed to evade virtualization-based detection. SOC teams should proactively hunt for this behavior in Azure Sentinel to identify and mitigate threats that leverage virtualization to persist or evade detection.

YARA Rule

rule antivm_vmware {
    meta:
        author = "x0r"
        description = "AntiVM checks for VMWare"
	version = "0.1"
    strings:
        $s1 = "vmware.exe" nocase
        $s2 = "vmware-authd.exe" nocase
        $s3 = "vmware-hostd.exe" nocase
        $s4 = "vmware-tray.exe" nocase
        $s5 = "vmware-vmx.exe" nocase
        $s6 = "vmnetdhcp.exe" nocase
        $s7 = "vpxclient.exe" nocase
    	$s8 = { b868584d56bb00000000b90a000000ba58560000ed }
    condition:
        any of them
}

Deployment Notes

This YARA rule can be deployed in the following contexts:

• Microsoft Defender for Endpoint — Custom indicators / advanced hunting
• Email Gateway — Attachment scanning
• File Share Monitoring — Periodic scanning of shared drives
• YARA CLI — Manual threat hunting on endpoints

This rule contains 8 string patterns in its detection logic.

• Source Rule

False Positive Guidance

• Scenario: A system administrator is performing a scheduled backup using Veeam Backup & Replication.
  Filter/Exclusion: Exclude processes related to veeambackup.exe or check for the presence of Veeam-specific process names in the event data.

• Scenario: A developer is running a virtual machine for testing purposes using VMware Workstation Player.
  Filter/Exclusion: Exclude processes associated with vmrun.exe or check for the presence of known VMware Workstation process names.

• Scenario: A system update task is executed via PowerShell script using Group Policy to deploy patches.
  Filter/Exclusion: Exclude PowerShell scripts that match known GPO update scripts or filter by the presence of gpupdate.exe or wuauclt.exe in the process tree.

• Scenario: A security analyst is running a VMware vSphere Client to monitor virtual machines.
  Filter/Exclusion: Exclude processes associated with vmware-client.exe or check for the presence of VMware vSphere-related process names.

• Scenario: A scheduled job using PowerShell is configured to run PowerShell scripts that interact with VMware APIs for automation.
  Filter/Exclusion: Exclude processes that match known PowerShell automation scripts or filter by the presence of powershell.exe with specific command-line arguments related to VMware.