Windows PowerShell Script Block With Malicious String

Description

The following analytic detects the execution of multiple offensive toolkits and commands by leveraging PowerShell Script Block Logging (EventCode=4104). This method captures and logs the full command sent to PowerShell, allowing for the identification of suspicious activities including several well-known tools used for credential theft, lateral movement, and persistence. If confirmed malicious, this could lead to unauthorized access, privilege escalation, and potential compromise of sensitive information within the environment.

Query · spl

`powershell` ScriptBlockText=* EventCode=4104 | stats count min(_time) as firstTime max(_time) as lastTime list(ScriptBlockText) as command values(Guid) as Guid values(Opcode) as Opcode values(Name) as Name values(Path) as Path values(ProcessID) as ProcessID values(ScriptBlockId) as ScriptBlockId values(ScriptBlockText) as ScriptBlockText by dest signature signature_id user_id vendor_product | eval command = mvjoin(command,"\n") | lookup malicious_powershell_strings command | where isnotnull(match) | `security_content_ctime(firstTime)` | `security_content_ctime(lastTime)` | `windows_powershell_script_block_with_malicious_string_filter`

Implementation guide

The following analytic requires PowerShell operational logs to be imported. Modify the powershell macro as needed to match the sourcetype or add index. This analytic is specific to 4104, or PowerShell Script Block Logging.

Known false positives

  • No false positives have been identified at this time. commands with overlap.

Analyst notes

Known false positives: No false positives have been identified at this time. commands with overlap.

Raw source Windows PowerShell Script Block With Malicious String · SPL
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Published by splunk/security_content ↗, licensed under Apache 2.0 ↗. Reproduced here unmodified. 
name: Windows PowerShell Script Block With Malicious String
id: 0f09cedd-10f1-4b9f-bdea-7a8b06ea575d
version: 7
creation_date: '2025-01-13'
modification_date: '2026-05-13'
author: Steven Dick
status: production
type: TTP
description: The following analytic detects the execution of multiple offensive toolkits and commands by leveraging PowerShell Script Block Logging (EventCode=4104). This method captures and logs the full command sent to PowerShell, allowing for the identification of suspicious activities including several well-known tools used for credential theft, lateral movement, and persistence. If confirmed malicious, this could lead to unauthorized access, privilege escalation, and potential compromise of sensitive information within the environment.
data_source:
    - Powershell Script Block Logging 4104
search: '`powershell` ScriptBlockText=* EventCode=4104 | stats count min(_time) as firstTime max(_time) as lastTime list(ScriptBlockText) as command values(Guid) as Guid values(Opcode) as Opcode values(Name) as Name values(Path) as Path values(ProcessID) as ProcessID values(ScriptBlockId) as ScriptBlockId values(ScriptBlockText) as ScriptBlockText by dest signature signature_id user_id vendor_product | eval command = mvjoin(command,"\n") | lookup malicious_powershell_strings command | where isnotnull(match) | `security_content_ctime(firstTime)` | `security_content_ctime(lastTime)` | `windows_powershell_script_block_with_malicious_string_filter`'
how_to_implement: The following analytic requires PowerShell operational logs to be imported. Modify the powershell macro as needed to match the sourcetype or add index. This analytic is specific to 4104, or PowerShell Script Block Logging.
known_false_positives: No false positives have been identified at this time. commands with overlap.
references:
    - https://attack.mitre.org/techniques/T1059/001/
    - https://github.com/PowerShellMafia/PowerSploit
    - https://github.com/PowerShellEmpire/
    - https://github.com/S3cur3Th1sSh1t/PowerSharpPack
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: The user $user_id$ ran a known malicious PowerShell string matching *$match$* on $dest$
    entity:
        field: dest
        type: system
        score: 50
threat_objects:
    - field: signature_id
      type: signature
analytic_story:
    - Malicious PowerShell
asset_type: Endpoint
mitre_attack_id:
    - T1059.001
product:
    - Splunk Enterprise
    - Splunk Enterprise Security
    - Splunk Cloud
category: endpoint
security_domain: threat
tests:
    - name: True Positive Test
      attack_data:
        - data: https://media.githubusercontent.com/media/splunk/attack_data/master/datasets/attack_techniques/T1552.006/powershell_gpp_discovery/win-powershell.log
          source: XmlWinEventLog:Microsoft-Windows-PowerShell/Operational
          sourcetype: XmlWinEventLog
      test_type: unit

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