DalKrypt10byDalKiT

Hunt Hypothesis

This rule detects the presence of the DalKrypt ransomware strain, which is known for encrypting files and leaving a distinctive ransom note, indicating a potential active compromise or staging of a ransomware payload. Proactively hunting for this signature allows the SOC team to identify low-severity infections early in the kill chain, enabling rapid containment before the encryption process propagates across the Azure environment.

YARA Rule

rule DalKrypt10byDalKiT
{
      meta:
		author="malware-lu"
strings:
		$a0 = { 68 00 10 40 00 58 68 [3] 00 5F 33 DB EB 0D 8A 14 03 80 EA 07 80 F2 04 88 14 03 43 81 FB [3] 00 72 EB FF E7 }

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

• Legacy Application Deployment via Group Policy: When deploying older, unsigned, or custom-built line-of-business applications (e.g., specialized industrial control software or legacy POS systems) via Group Policy Object (GPO) software installation, the executable or installer package may match the DalKrypt10byDalKiT signature if it utilizes specific packing techniques or contains known byte sequences associated with the DalKiT toolkit.

  • Filter/Exclusion: Exclude files located in specific application directories (e.g., C:\Program Files\LegacyApp\) or exclude processes initiated by Gpupdate.exe or Msiexec.exe when the parent process is Gpupdate.exe or Msiexec.exe and the file path matches the known application folder.

• Third-Party Antivirus/EDR Self-Update: During scheduled self-updates of third-party security agents (e.g., CrowdStrike Falcon, Carbon Black, or SentinelOne), the update service may download and execute a temporary binary or installer that is packed or signed in a way that triggers the YARA rule, particularly if the update package is compressed or obfuscated before execution.

  • Filter/Exclusion: Exclude files whose path contains the vendor’s specific update directory (e.g., C:\ProgramData\CrowdStrike\ or C:\Program Files\SentinelOne\) and where the parent process is the vendor’s update service (e.g., FalconService.exe, SentinelOneAgent.exe, or CbService.exe).

• Development Environment Build Artifacts: In developer workstations or build servers, running make, cmake, or MSBuild to compile C/C++ projects may generate intermediate object files or test binaries that contain specific debug symbols or linker artifacts matching the DalKrypt10byDalKiT pattern, especially if the project uses specific