Detects .NET red/black-team tools via name

Hunt Hypothesis

This rule identifies the execution of known .NET-based Red and Blue team utility names to distinguish legitimate security operations from potential adversary tooling masquerading as benign software. Proactively hunting for these indicators in Azure Sentinel allows the SOC to validate authorized testing activities while rapidly isolating suspicious .NET processes that may signal an attacker leveraging common tools to evade detection or establish persistence.

YARA Rule

rule HKTL_NET_NAME_AggressiveProxy {
    meta:
        description = "Detects .NET red/black-team tools via name"
        reference = "https://github.com/EncodeGroup/AggressiveProxy"
        author = "Arnim Rupp"
        date = "2021-01-22"
    strings:
        $name = "AggressiveProxy" 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/EncodeGroup/AggressiveProxy
• Source Rule

False Positive Guidance

Here are 5 specific false positive scenarios for the rule “Detects .NET red/blue-team tools via name,” along with suggested filters or exclusions:

• Scenario: Automated Backup Operations

  • Context: Enterprise backup solutions often utilize .NET-based agents (e.g., Veeam, Rubrik, or custom scripts) that run scheduled jobs during off-hours. These agents frequently spawn processes named Veeam.Backup.Service.exe or similar .NET wrappers that match the rule’s naming pattern for security tools.
  • Suggested Filter: Exclude process names containing specific backup vendor prefixes (e.g., *Veeam*, *Rubrik*) when executed by the SYSTEM account on dedicated backup servers, provided the parent process is a known scheduler service like TaskScheduler.exe.

• Scenario: Endpoint Detection and Response (EDR) Self-Scans

  • Context: The organization’s primary EDR solution (e.g., CrowdStrike Falcon or Microsoft Defender for Endpoint) includes internal .NET modules that perform real-time scanning and telemetry collection. These internal components often have names like FalconSensor.exe or MsMpEngService.exe which may be flagged as “Red/Black team tools” due to their security function, even though they are the baseline defense layer rather than an external audit tool.
  • Suggested Filter: Create a whitelist exclusion for known EDR process names and their specific SHA-256 hashes, ensuring that native security agents do not trigger alerts against themselves unless running from non-standard directories (e.g., C:\Program Files\*).

• Scenario: IT Asset Management & Patching Agents

  • Context: Automated patch management systems like SCCM (System Center Configuration Manager) or Ivanti utilize .NET agents to inventory hardware and deploy updates. These agents often spawn temporary processes with