Detects .NET red/black-team tools via name

Hunt Hypothesis

This rule identifies the execution of known .NET-based red and blue team utilities by matching process names against a curated list of security tooling signatures. Proactive hunting for these artifacts in Azure Sentinel is essential to distinguish legitimate security operations from adversarial activity that may mimic similar tools to evade detection or establish persistence within the environment.

YARA Rule

rule HKTL_NET_NAME_NativePayload_DNS2 {
    meta:
        description = "Detects .NET red/black-team tools via name"
        reference = "https://github.com/DamonMohammadbagher/NativePayload_DNS2"
        author = "Arnim Rupp"
        date = "2021-01-22"
    strings:
        $name = "NativePayload_DNS2" ascii wide
        $compile = "AssemblyTitle" ascii wide
    condition:
        (uint16(0) == 0x5A4D and uint32(uint32(0x3C)) == 0x00004550) and all of them
}

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 2 string patterns in its detection logic.

References

• https://github.com/DamonMohammadbagher/NativePayload_DNS2
• Source Rule

False Positive Guidance

Here are 4 specific false positive scenarios for the rule “Detects .NET red/black-team tools via name,” including suggested filters and exclusions:

• Scenario: Automated Vulnerability Scanning by Qualys or Tenable

  • Context: Enterprise vulnerability management platforms (e.g., Qualys Cloud Agent, Tenable Nessus) often deploy .NET-based agents that execute scanning modules with names resembling red-team tools (e.g., QualysAgent.exe, TenableOneScanner.dll). These agents run scheduled scans during business hours, triggering the rule when they probe network ports or enumerate services.
  • Filter/Exclusion: Create a whitelist based on the specific executable hash and parent process name. Exclude processes where the ImageName matches known vendor binaries (e.g., QualysAgent.exe, TenableOneScanner.exe) running under the context of the “System” or dedicated service accounts (e.g., DOMAIN\svc-qualys).

• Scenario: Microsoft Defender for Endpoint (MDE) Live Response

  • Context: When security analysts initiate a “Live Response” session on an endpoint to investigate an alert, MDE launches .NET-based diagnostic tools (such as DefenderTool.exe or Microsoft.Security.Client.dll) that mimic the behavior of red-team reconnaissance tools like BloodHound or SharpUp.
  • Filter/Exclusion: Filter alerts where the parent process is MsMpEng.exe (Antimalware Service Executable) or Sense.exe. Additionally, exclude events occurring within a specific “Investigation Window” tag if your SIEM supports custom attributes for analyst-initiated actions.

• Scenario: Scheduled PowerShell Reporting Jobs

  • Context: IT Operations teams frequently schedule nightly .NET-based reporting jobs (e.g., using PowerShell.exe loading custom .dll modules)