This YARA rule targets specific memory patterns or code artifacts associated with the aPackv098m signature, potentially indicating the presence of a known malware family or obfuscated payload in process memory. Proactively hunting for this signature allows the SOC team to identify low-severity threats that may be evading traditional network-based detections, ensuring early containment of persistent or stealthy adversaries within the Azure Sentinel environment.
rule aPackv098m
{
meta:
author="malware-lu"
strings:
$a0 = { 1E 06 8C C8 8E D8 05 [2] 8E C0 50 BE [2] 33 FF FC B2 ?? BD [2] 33 C9 50 A4 BB [2] 3B F3 76 }
condition:
$a0
}This YARA rule can be deployed in the following contexts:
This rule contains 1 string patterns in its detection logic.
Legacy Application Deployment via MSI/EXE Wrappers: The aPackv098m signature often matches specific byte patterns in older, custom-built installer wrappers or legacy Java/.NET applications that use specific packing algorithms (e.g., UPX, FSG, or custom proprietary packers) to reduce size. This is common in enterprise environments deploying legacy line-of-business (LOB) software or third-party utilities that have not been updated in years.
C:\Program Files\LegacyApp\bin\) or specific known-good hashes (SHA256) of the installer binaries. Additionally, exclude files with the .msi or .cab extension if the rule is primarily targeting executable payloads, or whitelist specific vendor names (e.g., LegacyCorp, OldVendor) in the file path.Scheduled Maintenance Jobs Using Packed Scripts: Some enterprise maintenance scripts (e.g., PowerShell or Python scripts) are packed using tools like PyInstaller or Nuitka to create standalone executables for distribution to non-technical endpoints. These packed executables may contain the specific byte sequence targeted by aPackv098m, especially if the packing tool version matches the signature’s target. This is frequently seen in scheduled tasks like nightly log rotation, database backups, or asset inventory collection.
PyInstaller, Nuitka) if the parent process is a recognized service or scheduled task (e.g., Task Scheduler, cron). Whitelist specific scheduled task names (e.g., NightlyBackup, AssetInventory) or exclude files in C:\Windows\Temp\ or C:\ProgramData\Maintenance\ if they are short-lived and cleaned up after execution.