Malicious PowerShell Process With Obfuscation Techniques

SPLUNK detection rule by David Dorsey, Splunk · Apache-2.0

The following analytic detects PowerShell processes launched with command-line arguments indicative of obfuscation techniques. It leverages data from Endpoint Detection and Response (EDR) agents, focusing on process names, parent processes, and complete command-line executions. This activity is significant because obfuscated PowerShell commands are often used by attackers to evade detection and execute malicious scripts. If confirmed malicious, this activity could lead to unauthorized code execution, privilege escalation, or persistent access within the environment, posing a significant security risk.

name: Malicious PowerShell Process With Obfuscation Techniques
id: cde75cf6-3c7a-4dd6-af01-27cdb4511fd4
version: 18
creation_date: '2020-04-29'
modification_date: '2026-05-13'
author: David Dorsey, Splunk
status: production
type: TTP
description: The following analytic detects PowerShell processes launched with command-line arguments indicative of obfuscation techniques. It leverages data from Endpoint Detection and Response (EDR) agents, focusing on process names, parent processes, and complete command-line executions. This activity is significant because obfuscated PowerShell commands are often used by attackers to evade detection and execute malicious scripts. If confirmed malicious, this activity could lead to unauthorized code execution, privilege escalation, or persistent access within the environment, posing a significant security risk.
data_source:
    - Sysmon EventID 1
search: '| tstats `security_content_summariesonly` count values(Processes.process) as process values(Processes.parent_process) as parent_process 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)`| eval num_obfuscation = (mvcount(split(process,"`"))-1) + (mvcount(split(process, "^"))-1) + (mvcount(split(process, "''"))-1) | search num_obfuscation > 10 | `malicious_powershell_process_with_obfuscation_techniques_filter`'
how_to_implement: The detection is based on data that originates from Endpoint Detection and Response (EDR) agents. These agents are designed to provide security-related telemetry from the endpoints where the agent is installed. To implement this search, you must ingest logs that contain the process GUID, process name, and parent process. Additionally, you must ingest complete command-line executions. These logs must be processed using the appropriate Splunk Technology Add-ons that are specific to the EDR product. The logs must also be mapped to the `Processes` node of the `Endpoint` data model. Use the Splunk Common Information Model (CIM) to normalize the field names and speed up the data modeling process.
known_false_positives: These characters might be legitimately on the command-line, but it is not common.
references: []
drilldown_searches:
    - name: View the detection results for - "$dest$"
      search: '%original_detection_search% | search  dest = "$dest$"'
      earliest_offset: $info_min_time$
      latest_offset: $info_max_time$
    - name: View risk events for the last 7 days for - "$dest$"
      search: '| from datamodel Risk.All_Risk | search normalized_risk_object IN ("$dest$") | stats count min(_time) as firstTime max(_time) as lastTime values(search_name) as "Search Name" values(risk_message) as "Risk Message" values(analyticstories) as "Analytic Stories" values(annotations._all) as "Annotations" values(annotations.mitre_attack.mitre_tactic) as "ATT&CK Tactics" by normalized_risk_object | `security_content_ctime(firstTime)` | `security_content_ctime(lastTime)`'
      earliest_offset: 7d
      latest_offset: "0"
finding:
    title: Powershell.exe running with potential obfuscated arguments on $dest$
    entity:
        field: dest
        type: system
        score: 50
analytic_story:
    - Malicious PowerShell
    - Hermetic Wiper
    - Data Destruction
    - GhostRedirector IIS Module and Rungan Backdoor
    - Hellcat Ransomware
asset_type: Endpoint
mitre_attack_id:
    - T1059.001
product:
    - Splunk Enterprise
    - Splunk Enterprise Security
    - Splunk Cloud
category: endpoint
security_domain: endpoint
tests:
    - name: True Positive Test
      attack_data:
        - data: https://media.githubusercontent.com/media/splunk/attack_data/master/datasets/attack_techniques/T1059.001/obfuscated_powershell/windows-sysmon.log
          source: XmlWinEventLog:Microsoft-Windows-Sysmon/Operational
          sourcetype: XmlWinEventLog
      test_type: unit

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fc62748b-0012-4144-9826-8d4a978f9526

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