CRYPToCRACksPEProtectorV093LukasFleischer

Hunt Hypothesis

This detection identifies the presence of PEProtector v093, a specific obfuscation technique often employed by adversaries to conceal malicious payloads within legitimate-looking executables and evade static analysis. Proactively hunting for this signature in Azure Sentinel is essential because low-severity alerts regarding such packers can indicate early-stage reconnaissance or sophisticated malware that might otherwise be overlooked until it executes its full payload.

YARA Rule

rule CRYPToCRACksPEProtectorV093LukasFleischer
{
      meta:
		author="malware-lu"
strings:
		$a0 = { 5B 81 E3 00 FF FF FF 66 81 3B 4D 5A 75 33 8B F3 03 73 3C 81 3E 50 45 00 00 75 26 0F B7 46 18 8B C8 69 C0 AD 0B 00 00 F7 E0 2D AB 5D 41 4B 69 C9 DE C0 00 00 03 C1 }

condition:
		$a0 at pe.entry_point
}

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

Here are 5 specific false positive scenarios for the CRYPToCRACksPEProtectorV093LukasFleischer detection rule, including suggested filters and exclusions:

• Scenario: Legitimate Software Deployment via Microsoft Endpoint Configuration Manager (SCCM)

  • Context: During scheduled maintenance windows, SCCM deploys enterprise applications (e.g., Adobe Acrobat Reader DC or Microsoft Office 365) that utilize PE-Protector for executable protection. The YARA rule triggers on the installer binaries (setup.exe) which contain the specific cryptographic signatures and packing structures associated with the rule.
  • Filter/Exclusion: Exclude processes running under the SMS_TSMClient or ccmexec.exe service account context where the file path contains \Microsoft Endpoint Configuration Manager\. Additionally, filter by process command line containing /deploy or /install flags to distinguish from user-initiated launches.

• Scenario: Automated Antivirus Signature Updates via CrowdStrike Falcon

  • Context: The CrowdStrike Falcon sensor performs hourly signature updates and scans protected executables in the C:\Program Files\CrowdStrike directory. The detection logic identifies the internal updater utility (csfalcon.exe) or its child processes as a match due to their use of similar PE packing techniques that mimic the rule’s target signatures.
  • Filter/Exclusion: Create an exclusion for file paths matching C:\Program Files\CrowdStrike\ and process names csfalcon.exe, csagent.exe, or csiserver.exe. Ensure the filter applies only when the parent process is a known system service (e.g., svchost.exe with specific service IDs).

• Scenario: Scheduled Backup Jobs Executing Veeam Backup & Replication Agents

  • Context: Nightly backup jobs initiated by the Vee