Splunk unknown stable spl

Windows Spearphishing Attachment Onenote Spawn Mshta

The following analytic detects OneNote spawning `mshta.exe`, a behavior often associated with spearphishing attacks. It leverages data from Endpoint Detection and Response (EDR) agents, focusing on process creation events where OneNote is the parent process. This activity is significant as it is commonly used by malware families like TA551, AsyncRat, Redline, and DCRAT to execute malicious scripts. If confirmed malicious, this could allow attackers to execute arbitrary code, potentially leading to data exfiltration, system compromise, or further malware deployment. Immediate investigation and containment are recommended.

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Detection Logic

| tstats `security_content_summariesonly` count min(_time) as firstTime max(_time) as lastTime 
FROM datamodel=Endpoint.Processes
  
WHERE Processes.parent_process_name IN ("onenote.exe", "onenotem.exe") `process_mshta`
  BY Processes.action Processes.dest Processes.original_file_name
     Processes.parent_process Processes.parent_process_exec Processes.parent_process_guid
     Processes.parent_process_id Processes.parent_process_name Processes.parent_process_path
     Processes.process Processes.process_exec Processes.process_guid
     Processes.process_hash Processes.process_id Processes.process_integrity_level
     Processes.process_name Processes.process_path Processes.user
     Processes.user_id Processes.vendor_product
| `drop_dm_object_name(Processes)`
| `security_content_ctime(firstTime)`
| `security_content_ctime(lastTime)`
| `windows_spearphishing_attachment_onenote_spawn_mshta_filter`

False Positives

⚠ No false positives known. Filter as needed.

Field Validations

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