Look for DCP Blowfish Init

Hunt Hypothesis

The DCP Blowfish Init detection rule identifies potential adversary activity associated with initializing a DCP (Data Collection Point) Blowfish process, which may indicate unauthorized data exfiltration or persistence mechanisms. SOC teams should proactively hunt for this behavior in Azure Sentinel to detect early-stage adversarial operations that could lead to data compromise or long-term system access.

YARA Rule

rule DCP_BLOWFISH_Init {
	meta:
		author = "_pusher_"
		description = "Look for DCP Blowfish Init"
		date = "2016-07"
	strings:
		$c0 = { 53 56 57 55 8B F2 8B F8 8B CF B2 01 A1 ?? ?? ?? ?? E8 ?? ?? ?? ?? 8B D8 8B C3 8B 10 FF 52 34 8B C6 E8 ?? ?? ?? ?? 50 8B C6 E8 ?? ?? ?? ?? 8B D0 8B C3 59 8B 30 FF 56 3C 8B 43 3C 85 C0 79 03 83 C0 07 C1 F8 03 E8 ?? ?? ?? ?? 8B F0 8B D6 8B C3 8B 08 FF 51 40 8B 47 40 8B 6B 3C 3B C5 7D 0F 6A 00 8B C8 8B D6 8B C7 8B 38 FF 57 30 EB 0D 6A 00 8B D6 8B CD 8B C7 8B 38 FF 57 30 8B 53 3C 85 D2 79 03 83 C2 07 C1 FA 03 8B C6 B9 FF 00 00 00 E8 ?? ?? ?? ?? 8B 53 3C 85 D2 79 03 83 C2 07 C1 FA 03 8B C6 E8 ?? ?? ?? ?? 8B C3 E8 ?? ?? ?? ?? 5D 5F 5E 5B C3 }
	condition:
		$c0
}

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

• Scenario: A system administrator is manually initiating a DCP (Data Collection Protocol) Blowfish encryption process as part of a routine security audit or data migration task.
  Filter/Exclusion: Check for the presence of a known admin user (e.g., root, admin, or a service account) and filter out events initiated from a known management console or command-line interface used for administrative tasks.

• Scenario: A scheduled job or automation script is running a DCP Blowfish Init operation to encrypt data backups or prepare for a secure data transfer.
  Filter/Exclusion: Include a filter for processes initiated by a known backup or automation tool (e.g., Veeam, Commvault, or rsync with encryption flags) and exclude events that occur outside of scheduled maintenance windows.

• Scenario: A legitimate application or service (e.g., OpenVPN, TLS proxy, or SSH tunnel) is using DCP Blowfish Init as part of its secure communication protocol.
  Filter/Exclusion: Filter events associated with known secure communication tools and exclude any activity that does not match the expected protocol or port usage for such services.

• Scenario: A developer is testing encryption functionality in a development environment, which includes invoking DCP Blowfish Init as part of a unit test or integration test.
  Filter/Exclusion: Exclude events that occur in development or test environments by checking the hostname, IP address, or environment variables (e.g., ENV=dev or TESTING=true).

• Scenario: A security tool or SIEM system is using DCP Blowfish Init to encrypt logs or data before sending them to a secure storage or analytics platform.
  Filter/Exclusion: Filter events that originate from known security tools (e.g., Splunk, ELK Stack, or Logstash) and exclude any activity that does not match the expected