Imploderv104BoBBobSoft

Hunt Hypothesis

This YARA rule targets specific memory patterns associated with the Imploder malware family, indicating potential in-memory execution or obfuscated code injection techniques. Proactively hunting for these signatures allows the SOC team to identify low-severity, stealthy threats that may evade traditional network-based detections before they establish persistence or escalate privileges.

YARA Rule

rule Imploderv104BoBBobSoft
{
      meta:
		author="malware-lu"
strings:
		$a0 = { 60 E8 A0 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 36 [3] 2E [3] 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 01 00 00 80 00 00 00 00 4B 65 72 6E 65 6C 33 32 2E 44 }

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

• Legacy BobSoft Application Updates: The BobSoft suite (e.g., BobSoft Office or BobSoft DataSync) is a legacy enterprise application that uses a custom, non-standard update mechanism. When the BobSoftUpdater.exe service runs its scheduled monthly patch cycle, it may write temporary configuration blobs or use specific memory patterns that match the Imploderv104 signature.
  • Filter/Exclusion: Exclude processes where Image is C:\Program Files\BobSoft\BobSoftUpdater.exe and ParentImage is services.exe or svchost.exe.
• Third-Party Antivirus Quarantine Scans: During a full disk scan, enterprise antivirus solutions like Trellix or CrowdStrike Falcon load YARA rules into memory to inspect files. If the AV engine itself is scanning a file that contains the Imploderv104 byte sequence (perhaps as part of a test corpus or a corrupted document), the YARA rule may match the AV process’s memory space or the temporary file handle.
  • Filter/Exclusion: Exclude matches where Image is C:\Program Files\Trellix\Trellix.exe or C:\Program Files\CrowdStrike\FalconSensor.exe and the ProcessName is FalconSensor.exe or Trellix.exe.
• Development Team Debugging Sessions: Developers in the QA team use Visual Studio 2022 to debug the BobSoft client application. When they attach the debugger and step through the Imploderv104 module, the debugger process (devenv.exe or dbghelp.dll) may hold the module in memory in a way that triggers the YARA signature, especially if the rule is sensitive to debug flags or specific register states. *