Freshbindv20gFresh

Hunt Hypothesis

This detection identifies the presence of the Freshbindv20gFresh malware variant on endpoints by leveraging a specific YARA signature to catch potential file-based infections. SOC teams should proactively hunt for this indicator in Azure Sentinel to validate its prevalence across the environment and assess whether low-severity alerts represent isolated incidents or early signs of a broader campaign requiring deeper investigation.

YARA Rule

rule Freshbindv20gFresh
{
      meta:
		author="malware-lu"
strings:
		$a0 = { 64 A1 00 00 00 00 55 89 E5 6A FF 68 1C A0 41 00 }

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

Here are 4 specific false positive scenarios for the Freshbindv20gFresh detection rule, along with suggested filters and exclusions:

• Scenario: Scheduled Antivirus Definition Updates

  • Context: Enterprise endpoint protection suites (e.g., CrowdStrike Falcon, Microsoft Defender for Endpoint) often download fresh signature databases or engine updates during off-hours. These processes frequently spawn temporary binaries that match the “Freshbind” pattern in their file headers or execution behavior, triggering the rule when they are merely updating local caches rather than indicating a new threat.
  • Filter/Exclusion: Create an exclusion based on the process image path and parent process. Exclude events where ProcessImage contains \Program Files\Microsoft Defender Antivirus\bin\MsMpEng.exe or \CrowdStrike\FalconSensor\csfalcon.exe, provided the parent process is the respective service host (e.g., svchost.exe).

• Scenario: Automated Patch Management Deployment

  • Context: During monthly maintenance windows, tools like Microsoft Endpoint Configuration Manager (SCCM) or Ivanti Neurons deploy new application patches. The deployment agents often extract fresh installation packages to temporary directories (C:\Windows\Temp), creating new executable files that mimic the signature of a “fresh bind” event before the actual installer runs.
  • Filter/Exclusion: Implement a time-based filter combined with a directory exclusion. Exclude alerts occurring between 02:00 and 04:00 UTC (standard maintenance window) where the FileCreatedPath is located within \Windows\Temp\ or \ProgramData\PatchManagement.

• Scenario: CI/CD Pipeline Artifact Generation

  • Context: In DevOps environments, build servers like Jenkins, GitLab Runners, or **Azure