PseudoSigner02MacromediaFlashProjector60Anorganix

Hunt Hypothesis

This rule identifies executable files that masquerade as legitimate Macromedia Flash Player binaries by embedding specific strings, a technique often used by adversaries to bypass signature-based detection and establish a foothold in the environment. Proactively hunting for these pseudo-signed artifacts in Azure Sentinel allows the SOC team to uncover low-and-slow persistence mechanisms or initial access payloads that may have evaded standard antivirus solutions due to their deceptive file naming and low severity classification.

YARA Rule

rule PseudoSigner02MacromediaFlashProjector60Anorganix
{
      meta:
		author="malware-lu"
strings:
		$a0 = { 90 90 90 90 68 [4] 67 64 FF 36 00 00 67 64 89 26 00 00 F1 90 90 90 90 83 EC 44 56 FF 15 24 81 49 00 8B F0 8A 06 3C 22 75 1C 8A 46 01 46 3C 22 74 0C 84 C0 74 08 8A 46 01 46 3C 22 75 F4 80 3E 22 75 0F 46 EB 0C }

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

• Scenario: A legacy internal web application or dashboard relies on an embedded Macromedia Flash Player (version 6.0) for specific data visualization components that have not yet been migrated to HTML5. The application server or client machines execute the FlashProjector.exe (or similar projector binary) to render these legacy assets.

  • Filter/Exclusion: Exclude execution of FlashProjector.exe (or flashplayer.exe v6.0) when the parent process is a known web server (e.g., w3wp.exe, httpd.exe, nginx.exe) or a specific browser process (e.g., chrome.exe, firefox.exe) and the file path resides within the application’s designated legacy assets directory (e.g., C:\InetPub\wwwroot\legacy\flash\).

• Scenario: An IT department is performing a scheduled maintenance task to update or patch a specific line of business (LOB) application that uses an older version of Flash for its reporting interface. The update process involves extracting or executing the projector binary to verify compatibility before deploying the new version to endpoints.

  • Filter/Exclusion: Exclude the rule if the execution occurs during a defined maintenance window (e.g., 02:00–04:00 UTC) and the parent process is a known deployment tool such as wsus.exe, ccmexec.exe (SCCM), or pdqdeploy.exe.

• Scenario: A quality assurance (QA) team is testing a new release of a desktop application that embeds a Flash-based help system or tutorial module. The QA engineer manually launches the application, which in turn spawns the Flash Projector to display the help content.

  • Filter/Exclusion: Exclude if the parent process is the specific LOB application executable (e.g., InventoryManager.exe) and the