Look for TEA Encryption

Hunt Hypothesis

Adversaries may use TEA encryption to obscure malicious payloads or exfiltrated data, making it harder to detect through traditional means. SOC teams should proactively hunt for TEA encryption in Azure Sentinel to identify potential data exfiltration or persistence mechanisms that evade standard detection methods.

YARA Rule

rule TEAN {
	meta:
		author = "_pusher_"
		description = "Look for TEA Encryption"
		date = "2016-08"
	strings:
		$c0 = { 2037EFC6 }
	condition:
		$c0
}

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 1 string patterns in its detection logic.

• Source Rule

False Positive Guidance

• Scenario: A system administrator is using 7-Zip to encrypt sensitive configuration files using TEA encryption for internal storage.
  Filter/Exclusion: Exclude processes initiated by the system admin user (e.g., username=admin) or filter by process name 7-Zip.

• Scenario: A scheduled backup job is using Veeam Backup & Replication to encrypt backup data using TEA encryption during off-peak hours.
  Filter/Exclusion: Exclude processes associated with the backup service account or filter by job name containing “backup” or “VEEAM”.

• Scenario: An IT support tool like SolarWinds Server & Application Monitor is encrypting log files using TEA encryption for secure storage.
  Filter/Exclusion: Exclude processes related to the SolarWinds service or filter by process name containing “SolarWinds”.

• Scenario: A database administrator is using MySQL with encryption plugins to encrypt data at rest, which may involve TEA-like encryption algorithms.
  Filter/Exclusion: Exclude processes initiated by the MySQL service account or filter by process name containing “mysqld”.

• Scenario: A CI/CD pipeline (e.g., Jenkins) is encrypting secrets using a custom script that implements TEA encryption for secure credential storage.
  Filter/Exclusion: Exclude processes initiated by the Jenkins service account or filter by process name containing “jenkins” or “Jenkins”.