splApache-2.0from splunk/security_content

Malicious PowerShell Process - Encoded Command

The following analytic detects the use of the EncodedCommand parameter in PowerShell processes. It leverages Endpoint Detection and Response (EDR) data to identify variations of the EncodedCommand parameter, including shortened forms and different command switch types. This activity can be significant because adversaries often use encoded commands to obfuscate malicious scripts, making detection harder. If confirmed malicious, this behavior could allow attackers to execute hidden code, potentially leading to unauthorized access, privilege escalation, or persistent threats within the environment. Review parallel events to determine legitimacy and tune based on known administrative scripts.

Quality

FP risk

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Forks

Views

Rule sourcedetections/endpoint/malicious_powershell_process___encoded_command.yml

| tstats `security_content_summariesonly`
  count min(_time) as firstTime
        max(_time) as lastTime
from datamodel=Endpoint.Processes where
`process_powershell`
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)`
| where match(process,"(?i)(?:^|\\s)(?:/(?!/)|--?|–{1,2}|—{1,2}|―{1,2})(?:ec|encodedcommand|encodedcomman|encodedcomma|encodedcomm|encodedcom|encodedco|encodedc|encoded|encode|encod|enco|enc|en|e(?=\\s))\\s+['\\\"]?[A-Za-z0-9+/=]{5,}['\\\"]?")
| `malicious_powershell_process___encoded_command_filter`