Detect GPGQwerty ransomware

Hunt Hypothesis

This hypothesis posits that adversaries are deploying the GPGQwerty ransomware variant to encrypt critical assets within the Azure environment, potentially leveraging initial footholds established through common entry vectors. The SOC team should proactively hunt for this specific signature in Azure Sentinel to validate early-stage infection indicators and prevent lateral movement before encryption impacts business continuity.

YARA Rule

rule crime_ransomware_windows_GPGQwerty: crime_ransomware_windows_GPGQwerty

{

meta:

author = "McAfee Labs"

description = "Detect GPGQwerty ransomware"

reference = "https://securingtomorrow.mcafee.com/mcafee-labs/ransomware-takes-open-source-path-encrypts-gnu-privacy-guard/"

strings:

$a = "gpg.exe –recipient qwerty  -o"

$b = "%s%s.%d.qwerty"

$c = "del /Q /F /S %s$recycle.bin"

$d = "[email protected]"

condition:

all 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 4 string patterns in its detection logic.

References

• https://securingtomorrow.mcafee.com/mcafee-labs/ransomware-takes-open-source-path-encrypts-gnu-privacy-guard/
• Source Rule

False Positive Guidance

Here are 5 specific false positive scenarios for the Detect GPGQwerty ransomware rule in an enterprise environment, including suggested filters and exclusions:

• Enterprise Backup Agent Encryption Jobs

  • Scenario: Scheduled backup agents (e.g., Veeam Backup & Replication, Commvault, or Rubrik) perform nightly encryption of large data sets. These processes often exhibit high CPU usage, rapid file creation/modification, and the use of cryptographic libraries that mimic ransomware behavior by locking files during the encryption window.
  • Filter/Exclusion: Create an exclusion rule for the specific service accounts (e.g., svc-veeam-backup) and executable paths (C:\Program Files\Veeam\Backup...). Additionally, filter out events occurring strictly within the defined maintenance window (e.g., 02:00–04:00 local time) where backup jobs are known to run.

• Software Deployment and Patch Management

  • Scenario: Automated patch management tools like Microsoft Endpoint Configuration Manager (MECM/SCCM) or Ivanti deploy updates that involve replacing system binaries, updating registry keys in bulk, and executing silent installers (msiexec.exe). These actions can trigger the rule if they modify a high volume of files in critical directories (e.g., C:\Windows\System32) simultaneously.
  • Filter/Exclusion: Exclude processes running under the context of deployment service accounts (e.g., DOMAIN\SCCM-Admin) and specific parent process names (ccmexec.exe, IvantiAgentService). Implement a logic check to ignore file modifications where the “Parent Process” is a known deployment orchestrator.

• Antivirus and EDR Real-Time Scanning

  • Scenario: The organization’s primary Endpoint Detection and Response (EDR