detect TrickBot in memory

Hunt Hypothesis

This detection rule identifies the presence of TrickBot malware within system memory to uncover active credential theft and lateral movement capabilities often missed by signature-based defenses alone. Proactively hunting for this behavior in Azure Sentinel is critical because early identification of in-memory artifacts allows the SOC team to isolate compromised endpoints before the adversary establishes persistence or exfiltrates sensitive data.

YARA Rule

rule Trickbot {
          meta:
            description = "detect TrickBot in memory"
            author = "JPCERT/CC Incident Response Group"
            rule_usage = "memory scan"
            hash1 = "2153be5c6f73f4816d90809febf4122a7b065cbfddaa4e2bf5935277341af34c"

          strings:
            $tagm1 = "<mcconf><ver>" wide
            $tagm2 = "</autorun></mcconf>" wide
            $tagc1 = "<moduleconfig><autostart>" wide
            $tagc2 = "</autoconf></moduleconfig>" wide
            $tagi1 = "<igroup><dinj>" wide
            $tagi2 = "</dinj></igroup>" wide
            $tags1 = "<servconf><expir>" wide
            $tags2 = "</plugins></servconf>" wide
            $tagl1 = "<slist><sinj>" wide
            $tagl2 = "</sinj></slist>" wide
          condition: all of ($tagm*) or all of ($tagc*) or all of ($tagi*) or all of ($tags*) or all of ($tagl*)
}

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 10 string patterns in its detection logic.

• Source Rule

False Positive Guidance

Here are 4 specific false positive scenarios for the detect TrickBot in memory rule, tailored for an enterprise environment:

• Scenario: Microsoft Defender Antivirus Real-Time Scanning

  • Context: The MsMpEng.exe process (Microsoft Defender) frequently injects code into other processes to perform real-time scanning and heuristic analysis. This behavior mimics TrickBot’s DLL injection techniques, often triggering memory-based detections when the scanner scans large user directories or email attachments.
  • Filter/Exclusion: Exclude events where the parent process is MsMpEng.exe or the source image path contains \Program Files\Windows Defender\. Additionally, filter out alerts where the injected module hash matches known Microsoft-signed binaries (e.g., mpclient.dll).

• Scenario: SCCM Software Update Deployment

  • Context: During scheduled maintenance windows, System Center Configuration Manager (SCCM) or Microsoft Endpoint Configuration Manager executes software updates via the ccmexec.exe service. This process often loads custom scripts and dynamic libraries into memory to apply patches, which can resemble TrickBot’s command-and-control initialization patterns in memory.
  • Filter/Exclusion: Create a rule exclusion for processes with the parent image name ccmexec.exe. Furthermore, add a time-based filter to suppress alerts originating from SCCM deployments during defined maintenance windows (e.g., 02:00 – 04:00 UTC).

• Scenario: Enterprise Endpoint Detection and Response (EDR) Agent Telemetry

  • Context: Third-party EDR agents like CrowdStrike (csagent.exe) or SentinelOne (S1Service.exe) utilize aggressive memory scanning and behavioral monitoring. These agents often hook into the system kernel to monitor process creation, a technique that generates significant memory activity indistinguishable from TrickBot’s persistence mechanisms.
  • **Filter/