KBySV028DLLshoooo

Hunt Hypothesis

This hunt detects the execution of a specific DLL module identified by the “KBySV028DLLshoooo” signature, which may indicate an adversary leveraging dynamic-link libraries for process injection or persistence. Proactively hunting for this behavior in Azure Sentinel is essential to identify low-severity anomalies that could represent early-stage lateral movement or stealthy command-and-control activities often missed by standard alerting thresholds.

YARA Rule

rule KBySV028DLLshoooo
{
      meta:
		author="malware-lu"
strings:
		$a0 = { B8 [4] BA [4] 03 C2 FF E0 [4] 60 E8 00 00 00 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 5 specific false positive scenarios for the detection rule KBySV028DLLshoooo, along with suggested filters or exclusions:

• Scenario: Legitimate deployment of Microsoft Office updates via the Configuration Manager (SCCM) client service (ccmexec.exe) loading a custom DLL during an office patch cycle.

  • Filter/Exclusion: Exclude processes where ImageFileName is ccmexec.exe and the parent process is WUAUService.exe, specifically when the loaded DLL path contains \Microsoft Office\Office16\.

• Scenario: Automated backup jobs initiated by Veeam Backup & Replication (Veeam.Backup.Service.exe) injecting a monitoring DLL into the SQL Server service to track transaction logs.

  • Filter/Exclusion: Create an exclusion for any process with ImageFileName matching Veeam.Backup.Service.exe where the loaded module name contains VeeamAgent.dll, regardless of the host machine.

• Scenario: Endpoint Detection and Response (EDR) agent, such as CrowdStrike Falcon (csfalconagent.exe), performing a scheduled integrity scan that dynamically loads signature definition DLLs into memory.

  • Filter/Exclusion: Exclude events where the parent process is csfalconagent.exe or csanalyzer.exe and the loaded DLL hash matches the known CrowdStrike signature database (e.g., specific SHA256 ranges).

• Scenario: System administrators running PowerShell scripts (powershell.exe) to deploy custom Group Policy templates, which load a helper DLL from the shared network drive.

  • Filter/Exclusion: Filter out detections where CommandLine contains -ExecutionPolicy Bypass and the loaded DLL path starts with \\FileServer\Shared\Scripts\, provided the process is running under an administrative account (e.g., `