ASPackv1061bAlexeySolodovnikov

Hunt Hypothesis

This detection identifies the presence of the ASPack v1061b packer signature, which adversaries often employ to obfuscate malicious payloads and evade static analysis by compressing executable structures. A SOC team should proactively hunt for this indicator in Azure Sentinel because its low severity suggests it may represent a stealthy initial foothold or a benign false positive that requires manual triage to distinguish from sophisticated evasion tactics.

YARA Rule

rule ASPackv1061bAlexeySolodovnikov
{
      meta:
		author="malware-lu"
strings:
		$a0 = { 60 E8 [4] 5D 81 ED EA A8 43 ?? B8 E4 A8 43 ?? 03 C5 2B 85 78 AD 43 ?? 89 85 84 AD 43 ?? 80 BD 6E AD 43 }

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 4 specific false positive scenarios for the ASPackv1061bAlexeySolodovnikov detection rule, along with targeted filters and exclusions:

• Scenario: Automated Patch Deployment via SCCM/Intune

  • Context: Enterprise endpoints running Microsoft Endpoint Configuration Manager (SCCM) or Intune often trigger this rule when the system applies compressed software updates. The ASPack compression signature is frequently present in the .msi or .exe payloads generated by the deployment engine, which are legitimate and signed.
  • Filter/Exclusion: Create a whitelist exclusion for processes originating from ccmsetup.exe, Microsoft.Solitaire.Core.exe, or IntuneManagementExtension.exe. Additionally, filter alerts where the file hash matches known good hashes stored in the enterprise artifact repository (e.g., via a “Known Good Hash” allowlist).

• Scenario: Scheduled Antivirus Definition Updates

  • Context: During nightly maintenance windows, legacy or third-party antivirus solutions (such as Symantec Endpoint Protection or McAfee) download and install updated definition databases. These updates are often distributed using ASPack compression to reduce bandwidth usage, triggering the YARA rule on the temporary extraction files before they are fully validated by the AV engine itself.
  • Filter/Exclusion: Exclude file paths located in standard update directories, such as C:\ProgramData\McAfee\Agent\Updates or C:\Windows\System32\ccm\CcmExec. Implement a time-based filter to suppress alerts for this rule between 01:00 and 05:00 local time on weekdays when these scheduled jobs typically run.

• Scenario: Deployment of Internal Line-of-Business (LOB) Applications

  • Context: IT operations teams frequently distribute custom internal tools or scripts wrapped in installers created with