This detection identifies potential malicious activity where adversaries utilize specific packing mechanisms to obfuscate executable files and evade signature-based defenses within the Windows environment. A proactive hunt is essential in Azure Sentinel to uncover stealthy threats that may bypass standard AV solutions by analyzing file characteristics and behavioral patterns associated with this YARA rule, ensuring early identification of low-severity but high-impact anomalies.
rule PACKWINv101p
{
meta:
author="malware-lu"
strings:
$a0 = { 8C C0 FA 8E D0 BC [2] FB 06 0E 1F 2E [4] 8B F1 4E 8B FE 8C DB 2E [4] 8E C3 FD F3 A4 53 B8 [2] 50 CB }
condition:
$a0 at pe.entry_point
}
This YARA rule can be deployed in the following contexts:
This rule contains 1 string patterns in its detection logic.
Here are 4 specific false positive scenarios for the PACKWINv101p detection rule in an enterprise environment, along with suggested filters and exclusions:
Scenario: Automated Patch Deployment via SCCM/Intune
msiexec.exe process invokes internal packaging scripts that match the signature of PACKWINv101p.C:\Windows\CCM\Agent\MsiInstaller.exe or C:\Program Files (x86)\Microsoft Intune Agent\IntuneManagementExtension.exe, and the command line contains /quiet or /norestart.Scenario: Antivirus Real-Time Scanning of Compressed Archives
.zip or .7z archive extracted by the user. The YARA rule triggers because the unpacking utility creates temporary files that mimic the structure of the PACKWINv101p payload.%TEMP%, C:\Windows\Temp) where the process name is MsMpEng.exe or FalconSensor.exe, and the file extension is .tmp.Scenario: Legacy Reporting Tool Execution