bambam004bedrock

Hunt Hypothesis

This rule targets the execution of the Bambam004bedrock YARA signature, which likely indicates the presence of a specific malware family or obfuscated payload attempting to establish a foothold on Azure-hosted workloads. Proactively hunting for this signature allows the SOC to identify low-severity, potentially stealthy intrusions before they escalate into lateral movement or data exfiltration within the Azure environment.

YARA Rule

rule bambam004bedrock
{
      meta:
		author="malware-lu"
strings:
		$a0 = { BF [4] 83 C9 FF 33 C0 68 [4] F2 AE F7 D1 49 51 68 [4] E8 11 0A 00 00 83 C4 0C 68 [4] FF 15 [4] 8B F0 BF [4] 83 C9 FF 33 C0 F2 AE F7 D1 49 BF [4] 8B D1 68 [4] C1 E9 02 F3 AB 8B CA 83 E1 03 F3 AA BF [4] 83 C9 FF 33 C0 F2 AE F7 D1 49 51 68 [4] E8 C0 09 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

• Scenario: A developer or DevOps engineer runs a local build pipeline or CI/CD agent (e.g., Jenkins, GitLab Runner, or Azure DevOps Agent) that executes a custom Python or Node.js script to generate temporary artifacts or perform data transformation. These scripts often contain generic strings or memory patterns that match the bambam004bedrock YARA signature, especially if the rule targets common library names or base64-encoded configuration blocks.

  • Filter/Exclusion: Exclude processes where the parent process is a known CI/CD agent (e.g., jenkins.exe, gitlab-runner.exe, vstsagent.exe) or where the working directory contains .git, node_modules, or venv subdirectories.

• Scenario: An endpoint protection platform (EPP) or anti-malware tool (e.g., CrowdStrike Falcon, Microsoft Defender for Endpoint, or Carbon Black) performs a real-time scan or on-demand scan of a large code repository or container image layer. The scanner may load file contents into memory for analysis, triggering the YARA rule if the rule matches common cryptographic constants, UUIDs, or specific string patterns found in legitimate open-source libraries (e.g., OpenSSL, zlib, or protobuf definitions).

  • Filter/Exclusion: Exclude detections where the process name matches known EPP components (e.g., csagent.exe, MsMpEng.exe, cbd.exe) or where the file path includes Program Files, Windows\System32, or C:\ProgramData in the context of a scan operation.

• Scenario: A database administrator or application server (e.g., SQL Server, PostgreSQL, or Oracle) executes a stored procedure or background job that processes large text blobs or JSON payloads. If the YARA rule matches specific string sequences (e.g., common JSON keys, SQL keywords, or base