md5 06e3ed58854daeacf1ed82c56a883b04

Hunt Hypothesis

The rule detects potential malicious activity involving a specific MD5 hash, which may indicate the presence of a known or unknown threat. SOC teams should proactively hunt for this behavior in Azure Sentinel to identify and mitigate potential compromise early, especially given the low severity rating suggesting further investigation is warranted.

YARA Rule

rule md5_06e3ed58854daeacf1ed82c56a883b04 {
    strings: $ = "$log_entry = serialize($ARINFO)"
    condition: any 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 1 string patterns in its detection logic.

• Source Rule

False Positive Guidance

• Scenario: Legitimate system update using Microsoft Update
  Filter/Exclusion: Exclude files with SHA1 or SHA256 hashes matching known Microsoft update packages.
  Example: file.sha1 == "a1b2c3d4e5f67890abcdef1234567890abcdef"

• Scenario: Scheduled backup job using Veeam Backup & Replication
  Filter/Exclusion: Exclude files with process names containing “veeam” or “backup”.
  Example: process.name contains "veeam"

• Scenario: Administrative task using PowerShell for log cleanup
  Filter/Exclusion: Exclude files with process names containing “powershell” and command lines related to log management.
  Example: process.name contains "powershell" and command_line contains "Clear-EventLog"

• Scenario: Antivirus scan using Bitdefender
  Filter/Exclusion: Exclude files with process names containing “bitdefender” or “bdagent”.
  Example: process.name contains "bdagent"

• Scenario: Database backup using MySQL scheduled task
  Filter/Exclusion: Exclude files with process names containing “mysqldump” or “mysql”.
  Example: process.name contains "mysqldump"