The hypothesis is that an adversary is checking for the presence of a VirtualBox virtual machine to avoid detection within a virtual environment. A SOC team should proactively hunt for this behavior in Azure Sentinel to identify potential adversarial evasion tactics and uncover hidden malware execution contexts.
YARA Rule
rule antivm_virtualbox {
meta:
author = "x0r"
description = "AntiVM checks for VirtualBox"
version = "0.1"
strings:
$s1 = "VBoxService.exe" nocase
condition:
any of them
}
This YARA rule can be deployed in the following contexts:
This rule contains 1 string patterns in its detection logic.
Scenario: A system administrator is using VBoxManage to manually check the status of a VirtualBox VM for troubleshooting.
Filter/Exclusion: Exclude processes where the command line includes VBoxManage --list or VBoxManage showvminfo.
Scenario: A scheduled job runs VirtualBox Guest Additions scripts to perform system maintenance tasks like disk cleanup or log rotation.
Filter/Exclusion: Exclude processes where the command line includes VBoxService or VBoxClient with known maintenance scripts.
Scenario: A developer is using VirtualBox to run a local development environment, and the system is performing regular system diagnostics via built-in tools like systemd or logrotate.
Filter/Exclusion: Exclude processes initiated by the root user or those with command lines containing systemd or logrotate.
Scenario: A security tool like OSSEC or Tripwire is running integrity checks that temporarily access VirtualBox components for audit purposes.
Filter/Exclusion: Exclude processes with parent process names like ossec or tripwire, or those with command lines containing audit or check.
Scenario: A system is running VirtualBox Guest Additions to enable shared folders or seamless mode, which can trigger anti-VM checks.
Filter/Exclusion: Exclude processes where the command line includes VBoxAdditions or VBoxSharedFolders and are associated with legitimate guest additions services.