DES [sbox]

Hunt Hypothesis

The DES [sbox] rule detects potential cryptographic algorithm misuse or obfuscation techniques that may indicate advanced persistent threat activity leveraging deprecated encryption methods. SOC teams should proactively hunt for this behavior in Azure Sentinel to identify and mitigate potential data exfiltration or encryption-based attacks that evade traditional detection mechanisms.

YARA Rule

rule DES_sbox
{	meta:
		author = "_pusher_"
		date = "2015-05"
		description = "DES [sbox]"
	strings:
		$c0 = { 00 04 01 01 00 00 00 00 00 00 01 00 04 04 01 01 04 00 01 01 04 04 01 00 04 00 00 00 00 00 01 00 00 04 00 00 00 04 01 01 04 04 01 01 00 04 00 00 04 04 00 01 04 00 01 01 00 00 00 01 04 00 00 00 }
	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: Scheduled backup job using tar or rsync
  Filter/Exclusion: process.name != "tar" && process.name != "rsync"

• Scenario: System update via yum or apt
  Filter/Exclusion: process.name != "yum" && process.name != "apt"

• Scenario: Admin performing disk cleanup using dd or rm
  Filter/Exclusion: process.name != "dd" && process.name != "rm"

• Scenario: Log rotation using logrotate
  Filter/Exclusion: process.name != "logrotate"

• Scenario: Database dump using mysqldump or pg_dump
  Filter/Exclusion: process.name != "mysqldump" && process.name != "pg_dump"