FSGv110EngdulekxtMicrosoftVisualBasic5060

Hunt Hypothesis

This detection identifies potential adversary activity involving obfuscated or suspicious Microsoft Visual Basic scripts that match specific YARA signatures for known malicious patterns. Proactive hunting in Azure Sentinel is essential to uncover stealthy script-based attacks that may evade standard signature-based defenses and require deeper behavioral analysis.

YARA Rule

rule FSGv110EngdulekxtMicrosoftVisualBasic5060
{
      meta:
		author="malware-lu"
strings:
		$a0 = { C1 CB 10 EB 01 0F B9 03 74 F6 EE 0F B6 D3 8D 05 83 [2] EF 80 F3 F6 2B C1 EB 01 DE 68 77 }

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 3-5 specific false positive scenarios for the FSGv110EngdulekxtMicrosoftVisualBasic5060 detection rule, which targets Microsoft Visual Basic (VB) artifacts often associated with legacy scripting or macro execution:

• Scenario: Scheduled Macro Execution in Legacy ERP Systems

  • Context: Enterprise Resource Planning (ERP) systems like SAP or Oracle NetSuite often rely on VB-based macros to run nightly data reconciliation jobs. When the scheduled task triggers, it launches a VB runtime process that matches the YARA signature.
  • Filter/Exclusion: Create an exclusion based on the specific parent process (svchost.exe or taskeng.exe) and the known file path of the ERP application directory (e.g., C:\Program Files\SAP\FrontEnd\*). Additionally, exclude events occurring during defined maintenance windows (e.g., 02:00–04:00 UTC).

• Scenario: Deployment of VBScript-Based Configuration Scripts via SCCM

  • Context: System Center Configuration Manager (SCCM) or Microsoft Endpoint Configuration Manager frequently deploys custom .vbs scripts to configure workstation settings, install patches, or update GPOs. These scripts often invoke the Visual Basic runtime engine, triggering the rule during deployment cycles.
  • Filter/Exclusion: Filter alerts where the parent process is ccmexec.exe (SCCM agent) and the file extension is .vbs. Alternatively, exclude hashes of known good configuration scripts stored in a centralized artifact repository.

• Scenario: Automated Reporting via Microsoft Power BI Desktop or Excel Services

  • Context: Data analysts using Microsoft Power BI Desktop or automated Excel Services often utilize embedded VB code for data transformation and report generation. When these tools run background refreshes or export functions, the underlying VB engine is invoked, mimicking