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https://github.com/splunk/security_content
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Eric
76 lines
3.7 KiB
YAML
76 lines
3.7 KiB
YAML
name: PowerShell Script Block With URL Chain
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id: 4a3f2a7d-6402-4e64-a76a-869588ec3b57
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version: 6
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date: '2025-05-02'
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author: Steven Dick
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status: production
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type: TTP
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description: The following analytic identifies suspicious PowerShell script execution
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via EventCode 4104 that contains multiple URLs within a function or array. It leverages
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PowerShell operational logs to detect script blocks with embedded URLs, often indicative
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of obfuscated scripts or those attempting to download secondary payloads. This activity
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is significant as it may signal an attempt to execute malicious code or download
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additional malware. If confirmed malicious, this could lead to code execution, further
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system compromise, or data exfiltration. Review parallel processes and the full
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script block for additional context and related artifacts.
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data_source:
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- Powershell Script Block Logging 4104
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search: '`powershell` EventCode=4104 ScriptBlockText IN ("*http:*","*https:*") | regex
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ScriptBlockText="(\"?(https?:\/\/(?:www\.)?[-a-zA-Z0-9@:%._\+~#=]{1,256}\.[a-zA-Z0-9()]{1,6}\b(?:[-a-zA-Z0-9()@:%_\+.~#?&\/=]*))\"?(?:,|\))?){2,}"
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| rex max_match=20 field=ScriptBlockText "(?<url>https?:\/\/(?:www\.)?[-a-zA-Z0-9@:%._\+~#=]{1,256}\.[a-zA-Z0-9()]{1,6}\b(?:[-a-zA-Z0-9()@:%_\+.~#?&\/=]*))"
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signature signature_id user_id vendor_product EventID Guid Opcode Name Path ProcessID
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ScriptBlockId ScriptBlockText | `security_content_ctime(firstTime)` | `security_content_ctime(lastTime)`
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| `powershell_script_block_with_url_chain_filter`'
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how_to_implement: The following analytic requires PowerShell operational logs to be
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imported. Modify the powershell macro as needed to match the sourcetype or add index.
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This analytic is specific to 4104, or PowerShell Script Block Logging.
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known_false_positives: Unknown, possible custom scripting.
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references:
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- https://www.mandiant.com/resources/blog/tracking-evolution-gootloader-operations
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- https://thedfirreport.com/2022/05/09/seo-poisoning-a-gootloader-story/
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- https://attack.mitre.org/techniques/T1059/001/
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drilldown_searches:
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- name: View the detection results for - "$dest$" and "$user$"
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search: '%original_detection_search% | search dest = "$dest$" user = "$user$"'
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earliest_offset: $info_min_time$
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latest_offset: $info_max_time$
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- name: View risk events for the last 7 days for - "$dest$" and "$user$"
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search: '| from datamodel Risk.All_Risk | search normalized_risk_object IN ("$dest$",
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"$user$") starthoursago=168 | stats count min(_time) as firstTime max(_time)
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as lastTime values(search_name) as "Search Name" values(risk_message) as "Risk
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Message" values(analyticstories) as "Analytic Stories" values(annotations._all)
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as "Annotations" values(annotations.mitre_attack.mitre_tactic) as "ATT&CK Tactics"
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by normalized_risk_object | `security_content_ctime(firstTime)` | `security_content_ctime(lastTime)`'
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earliest_offset: $info_min_time$
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latest_offset: $info_max_time$
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rba:
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message: A suspicious powershell script used by $user_id$ on host $dest$ contains
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URLs in an array, this is commonly used for malware.
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risk_objects:
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- field: dest
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type: system
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score: 80
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- field: user_id
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type: user
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score: 80
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threat_objects: []
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tags:
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analytic_story:
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- Malicious PowerShell
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asset_type: Endpoint
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mitre_attack_id:
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- T1059.001
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- T1105
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product:
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- Splunk Enterprise
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- Splunk Enterprise Security
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- Splunk Cloud
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security_domain: endpoint
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tests:
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- name: True Positive Test
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attack_data:
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- data: https://media.githubusercontent.com/media/splunk/attack_data/master/datasets/malware/gootloader/partial_ttps/windows-powershell-xml.log
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source: XmlWinEventLog:Microsoft-Windows-PowerShell/Operational
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sourcetype: XmlWinEventLog
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