mirror of
https://github.com/splunk/security_content
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Bhavin Patel
75 lines
3.0 KiB
YAML
75 lines
3.0 KiB
YAML
name: PowerShell Script Block With URL Chain
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id: 4a3f2a7d-6402-4e64-a76a-869588ec3b57
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version: 1
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date: '2023-06-13'
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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 a suspicious PowerShell script execution via EventCode 4104 that contains multiple URLs within a function or array.
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This is typically found in obfuscated PowerShell or PowerShell executing embedded .NET or binary files that are attempting to download 2nd stage payloads.
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During triage, review parallel processes within the same timeframe. Review the full script block to identify other related artifacts.
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data_source:
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- Powershell 4104
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search: '`powershell` EventCode=4104 ScriptBlockText IN ("*http:*","*https:*")
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| regex 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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| eval Path = case(isnotnull(Path),Path,true(),"unknown")
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| stats count min(_time) as firstTime max(_time) as lastTime list(ScriptBlockText) as command values(Path) as file_name values(UserID) as user values(url) as url dc(url) as url_count by ActivityID, Computer, EventCode
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| rename Computer as dest, EventCode as signature_id
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| `security_content_ctime(firstTime)`
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| `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
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to be imported. Modify the powershell macro as needed to match the sourcetype or
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add index. 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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tags:
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analytic_story:
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- Malicious PowerShell
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asset_type: Endpoint
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confidence: 80
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impact: 100
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message: A suspicious powershell script used by $user$ on host $dest$ contains $url_count$ URLs in an array, this is commonly used for malware.
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mitre_attack_id:
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- T1059.001
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- T1105
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observable:
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- name: dest
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type: Endpoint
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role:
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- Victim
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- name: user
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type: User
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role:
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- Victim
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- name: file_name
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type: File Name
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role:
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- Attacker
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- name: url
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type: URL String
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role:
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- Attacker
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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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required_fields:
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- _time
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- EventCode
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- ActivityID
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- Computer
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- ScriptBlockText
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risk_score: 80
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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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