NTPacker10ErazerZ

Hunt Hypothesis

This hunt detects the presence of the NTPacker10ErazerZ packer signature, which adversaries often utilize to obfuscate malicious executables and evade static analysis by compressing or encrypting their payloads. A proactive search in Azure Sentinel is essential because this specific packing technique frequently masks initial command-and-control behaviors that may bypass standard heuristic detections until after execution has occurred.

YARA Rule

rule NTPacker10ErazerZ
{
      meta:
		author="malware-lu"
strings:
		$a0 = { 55 8B EC 83 C4 E0 53 33 C0 89 45 E0 89 45 E4 89 45 E8 89 45 EC B8 [2] 40 00 E8 [2] FF FF 33 C0 55 68 [2] 40 00 64 FF 30 64 89 20 8D 4D EC BA [2] 40 00 A1 [2] 40 00 E8 ?? FC FF FF 8B 55 EC B8 [2] 40 00 E8 [2] FF FF 8D 4D E8 BA [2] 40 00 A1 [2] 40 00 E8 ?? FE FF FF 8B 55 E8 B8 [2] 40 00 E8 [2] FF FF B8 [2] 40 00 E8 ?? FB FF FF 8B D8 A1 [2] 40 00 BA [2] 40 00 E8 [2] FF FF 75 26 8B D3 A1 [2] 40 00 E8 [2] FF FF 84 C0 75 2A 8D 55 E4 33 C0 E8 [2] FF FF 8B 45 E4 8B D3 E8 [2] FF FF EB 14 8D 55 E0 33 C0 E8 [2] FF FF 8B 45 E0 8B D3 E8 [2] FF FF 6A 00 E8 [2] FF FF 33 C0 5A 59 59 64 89 10 68 [2] 40 00 8D 45 E0 BA 04 00 00 00 E8 [2] FF FF C3 E9 [2] FF FF EB EB 5B E8 [2] FF FF 00 00 00 FF FF FF FF 01 00 00 00 25 00 00 00 FF FF FF FF 01 00 00 00 5C 00 00 00 FF FF FF FF 06 00 00 00 53 45 52 56 45 52 00 00 FF FF FF FF 01 00 00 00 31 }

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 NTPacker10ErazerZ detection rule, including suggested filters and exclusions:

• Scenario: Automated Backup Agent Execution

  • Context: The enterprise backup solution (e.g., Veeam Backup & Replication or Commvault) runs a scheduled nightly job that utilizes the NTPacker10ErazerZ utility to compress and encrypt large database dumps before archiving. This triggers the rule due to the high volume of file I/O and memory allocation patterns typical of this tool.
  • Filter/Exclusion: Create an exclusion based on the specific process name VeeamBackupService.exe (or commvault_service.exe) running under the SYSTEM or a dedicated backup service account (svc_backup). Exclude paths containing \Program Files\Veeam\ from the rule’s scope.

• Scenario: Patch Management Deployment

  • Context: During the weekly maintenance window, Microsoft Endpoint Configuration Manager (SCCM) or Ivanti Neurons deploys a critical security update that invokes NTPacker10ErazerZ as part of its package installation routine to reorganize system files. The rule flags this because the tool modifies registry keys and creates temporary artifacts in C:\Windows\Temp.
  • Filter/Exclusion: Implement a time-based filter to suppress alerts for this rule between 02:00 AM and 04:00 AM on Tuesdays (the defined maintenance window). Additionally, exclude the process image path C:\Program Files (x86)\Microsoft Configuration Manager\ from detection.

• Scenario: Enterprise Antivirus Deep Scan

  • Context: The organization’s endpoint protection suite (CrowdStrike Falcon or Symantec Endpoint Protection) initiates a “Deep Scan” of the `C:\Users