EXEShieldV06SMoKE

Hunt Hypothesis

This rule detects the presence of the EXEShieldV06SMoKE YARA signature, which typically indicates the use of a specific executable shielding or packing technique often employed by adversaries to obscure binary characteristics and evade static analysis. Proactively hunting for this pattern in Azure Sentinel allows the SOC team to identify potentially obfuscated malware or trojans that may have slipped past initial detection controls, ensuring early visibility into low-severity threats that could serve as precursors to more complex attacks.

YARA Rule

rule EXEShieldV06SMoKE
{
      meta:
		author="malware-lu"
strings:
		$a0 = { E8 04 00 00 00 83 60 EB 0C 5D EB 05 45 55 EB 04 B8 EB F9 00 C3 E8 00 00 00 00 5D 81 ED D4 1A 40 00 EB 01 00 8D B5 5E 1B 40 00 BA A1 0B 00 00 EB 01 00 8D 8D FF 26 40 00 8B 09 E8 14 00 00 00 83 EB 01 00 8B FE E8 00 00 00 00 58 83 C0 07 50 C3 00 EB 04 58 40 }
	$a1 = { E8 04 00 00 00 83 60 EB 0C 5D EB 05 45 55 EB 04 B8 EB F9 00 C3 E8 00 00 00 00 5D 81 ED D4 1A 40 00 EB 01 00 8D B5 5E 1B 40 00 BA A1 0B 00 00 EB 01 00 8D 8D FF 26 40 00 8B 09 E8 14 00 00 00 83 EB 01 00 8B FE E8 00 00 00 00 58 83 C0 07 50 C3 00 EB 04 58 40 50 C3 8A 06 46 EB 01 00 D0 C8 E8 14 00 00 00 83 EB 01 00 2A C2 E8 00 00 00 00 5B 83 C3 07 53 C3 00 EB 04 5B 43 53 C3 EB 01 00 32 C2 E8 0B 00 00 00 00 32 C1 EB 01 00 C0 C0 02 EB 09 2A C2 5B EB 01 00 43 53 C3 88 07 EB 01 00 47 4A 75 B4 90 }

condition:
		$a0 at pe.entry_point or $a1 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 2 string patterns in its detection logic.

• Source Rule

False Positive Guidance

• Scenario: Legitimate application installation or update via Microsoft Installer (MSI) or custom installers that embed the EXEShield protection mechanism to prevent tampering or reverse engineering of the executable.
  • Filter/Exclusion: Exclude processes where the parent process is msiexec.exe, setup.exe, or install.exe and the file path contains \Program Files\ or \Program Files (x86)\.
• Scenario: Execution of protected enterprise software binaries (e.g., Adobe Creative Cloud, JetBrains IDEs, or specific banking/finance applications) that use EXEShield for code integrity and anti-debugging features during normal user interaction.
  • Filter/Exclusion: Allowlist known vendor directories such as \Adobe\, \JetBrains\, or specific finance application folders, and exclude if the process is spawned by a standard user interface process like explorer.exe or winword.exe.
• Scenario: Scheduled maintenance jobs or service updates that restart or re-register protected executables, often triggered by Windows Task Scheduler or service control managers.
  • Filter/Exclusion: Exclude if the parent process is svchost.exe (specifically for the Task Scheduler service) or services.exe, and the command line contains arguments like /install, /update, or /reboot.
• Scenario: Development or QA environments where developers run protected test builds or staging applications locally, often from non-standard directories like C:\Dev\ or D:\Builds\.
  • Filter/Exclusion: Exclude if the user account belongs to a Dev or QA security group, or if the file path matches common development directories such as \Dev\, \Builds\, or \Temp\ (with caution).
• Scenario: Antivirus or endpoint protection