Retefe

Hunt Hypothesis

The Retefe hypothesis detects potential adversary behavior involving the use of a known malicious actor’s infrastructure or tactics, indicating possible compromise within the environment. SOC teams should proactively hunt for this behavior in Azure Sentinel to identify and mitigate early-stage threats associated with the Retefe group.

YARA Rule

rule Retefe
{
meta:
	author = "bartblaze"
	description = "Retefe"
strings:
	$string0 = "01050000"
	$string1 = "00000000"
	$string2 = "5061636b61676500"
	$string3 = "000000000000000000000000000000000000000000000000000000000000000000000000000000"
	$string4 = "{\\stylesheet{ Normal;}{\\s1 heading 1;}{\\s2 heading 2;}}"
	$string5 = "02000000"
condition:
	5 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 6 string patterns in its detection logic.

• Source Rule

False Positive Guidance

• Scenario: Scheduled system backup using Veeam Backup & Replication
  Filter/Exclusion: Exclude processes related to veeambackup.exe or check for the presence of a known backup job name in the process command line.

• Scenario: Regular Windows Update or Group Policy synchronization task
  Filter/Exclusion: Exclude processes with command lines containing wuauclt.exe, gupdate.exe, or gpupdate.exe.

• Scenario: Ansible playbook execution for configuration management
  Filter/Exclusion: Exclude processes with command lines containing ansible-playbook and check for known Ansible inventory files or playbooks.

• Scenario: Docker container orchestration or image pull via Kubernetes
  Filter/Exclusion: Exclude processes with command lines containing docker, kubectl, or crictl, and check for container runtime identifiers.

• Scenario: SQL Server Agent job execution for routine database maintenance
  Filter/Exclusion: Exclude processes with command lines containing sqlagent.exe or check for known SQL Server Agent job names in the process arguments.