md5 50be694a82a8653fa8b31d049aac721a

Hunt Hypothesis

The detection rule identifies potential malicious activity associated with the MD5 hash 50be694a82a8653fa8b31d049aac721a, which may indicate the presence of known malicious payloads. SOC teams should proactively hunt for this behavior in Azure Sentinel to identify and mitigate potential threats early, especially given the low severity rating which may mask more significant underlying activity.

YARA Rule

rule md5_50be694a82a8653fa8b31d049aac721a {
    strings: $ = "(preg_match('/\\/admin\\/Cms_Wysiwyg\\/directive\\/index\\//', $_SERVER['REQUEST_URI']))"
    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
• Source Rule

False Positive Guidance

• Scenario: A system backup tool (e.g., Veeam, Acronis) is running a scheduled backup job that includes a known legitimate file with the MD5 hash 50be694a82a8653fa8b31d049aac721a.
  Filter/Exclusion: Check for processes related to backup tools (e.g., veeam.exe, acronis.exe) or use a filter for processes running under a backup service account.

• Scenario: A software update or patching tool (e.g., Microsoft Update, SCCM) is deploying a legitimate file with the same MD5 hash during a routine patching cycle.
  Filter/Exclusion: Filter processes associated with patching tools (e.g., wuauserv.exe, ccmexec.exe) or check for the presence of update-related registry keys or scheduled tasks.

• Scenario: A system management tool (e.g., Puppet, Chef) is executing a configuration management task that includes a file with the MD5 hash 50be694a82a8653fa8b31d049aac721a as part of a known configuration baseline.
  Filter/Exclusion: Exclude processes related to configuration management tools (e.g., puppetd.exe, chef-client.exe) or check for the presence of configuration management service accounts or scheduled tasks.

• Scenario: A legitimate log file (e.g., from a SIEM tool like Splunk or ELK stack) is being generated with a hash that matches the rule due to a known file format or internal processing.
  Filter/Exclusion: Filter files with known log file extensions (e.g., .log, .json) or check for processes related to log management tools (e.g., splunkd.exe, `logstash