Disclosed hacktool set - file Blast.bat

Hunt Hypothesis

This hypothesis targets adversaries deploying batch scripts like “Blast.bat” to establish a foothold and execute malicious payloads within the Azure environment. Proactive hunting for this behavior is critical in Azure Sentinel to identify early-stage lateral movement or command execution that may bypass standard signature-based detections, ensuring rapid containment of potential compromise chains.

YARA Rule

rule Hacktools_CN_Burst_Blast {
	meta:
		description = "Disclosed hacktool set - file Blast.bat"
		author = "Florian Roth"
		date = "17.11.14"
		score = 60
		hash = "b07702a381fa2eaee40b96ae2443918209674051"
	strings:
		$s0 = "@sql.exe -f ip.txt -m syn -t 3306 -c 5000 -u http:" ascii
		$s1 = "@echo off" fullword ascii
	condition:
		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.

• Source Rule

False Positive Guidance

Here are 5 specific false positive scenarios for the “Disclosed hacktool set - file Blast.bat” detection rule, including suggested filters and exclusions:

• Scenario: Legacy IT Operations Team running a custom maintenance script named Blast.bat located in C:\Scripts\IT_Ops to clean up temporary logs on all domain-joined workstations.

  • Suggested Filter/Exclusion: Create an exclusion rule based on the file path (C:\Scripts\IT_Ops\Blast.bat) and the user context (DOMAIN\IT_OPS_GROUP). Ensure the script is signed with a trusted enterprise certificate if possible, or whitelist the specific file hash.

• Scenario: A scheduled task named “Daily Backup Cleanup” executed by the local system account on SQL Server instances, which invokes Blast.bat to archive transaction logs before the backup job begins.

  • Suggested Filter/Exclusion: Exclude events where the parent process is Task Scheduler (svchost.exe) and the running user is NT SYSTEM. Additionally, filter by the specific scheduled task name “Daily Backup Cleanup” if your EDR supports task-name correlation.

• Scenario: The Help Desk utilizes a standardized deployment tool (e.g., Microsoft Endpoint Configuration Manager or SCCM) that pushes a utility script named Blast.bat to endpoints during the initial onboarding phase of new laptops.

  • Suggested Filter/Exclusion: Whitelist the file hash of the specific Blast.bat deployed via SCCM. Alternatively, filter out alerts where the process command line contains flags indicating an automated deployment (e.g., /quiet, /norestart) and the user context is SYSTEM.

• Scenario: The Security Operations Center runs a nightly vulnerability scan using Qualys or Tenable, which temporarily drops a helper script named Blast.bat in the %TEMP% directory