Armadillo v1xx v2xx Silicon Realms Toolworks

Hunt Hypothesis

This rule identifies the presence of Armadillo malware variants, a known threat actor toolset associated with Silicon Realms and Toolworks, which often leverage custom encryption and obfuscation to evade standard signature-based detections. Proactively hunting for these specific YARA signatures allows the SOC to uncover dormant or active implants in Azure environments before they can establish persistence or execute lateral movement, addressing a gap in coverage for low-severity, targeted threat actor tooling.

YARA Rule

rule Armadillo_v1xx_v2xx_Silicon_Realms_Toolworks: PEiD
{
    strings:
        $a = { 55 8B EC 6A FF 68 50 8C 4C 00 68 D0 82 4A 00 64 A1 }
    condition:
        $a 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 security team deploys a custom YARA scanning agent (e.g., via yara CLI or integrated into a SIEM like Splunk/QRadar) that loads the Armadillo_v1xx_v2xx_Silicon_Realms_Toolworks.yar file into memory to scan network captures or host filesystems. The rule matches itself because the signature strings (e.g., Silicon Realms, Toolworks, Armadillo) are present in the loaded rule file or the scanner’s configuration cache.

  • Filter/Exclusion: Exclude processes where the parent process is a known YARA scanner (e.g., yara.exe, yara64.exe, yara-python) or where the file path contains /yara/ or \.yar$ in the filename.

• Scenario: A developer or QA engineer tests the Armadillo implant in an isolated lab environment using a virtual machine (e.g., Hyper-V, VMware) and runs the tool from a shared network drive or a local test folder (e.g., C:\Lab\Armadillo_Test\). The tool’s memory footprint or on-disk artifact matches the YARA signature during routine file integrity monitoring (FIM) or EDR telemetry collection.

  • Filter/Exclusion: Exclude alerts where the process path contains \\Lab\\, \\Test\\, \\Dev\\, or \\QA\\ in the directory path, or where the hostname matches a lab-specific naming convention (e.g., LAB-VM-01, TEST-WIN-05).

• Scenario: An endpoint detection and response (EDR) agent (e.g., CrowdStrike, Defender for Endpoint) performs a full system scan or on-demand scan that includes loading YARA rules into memory for real-time matching. The EDR’s internal