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mhaag-spl
68 lines
2.7 KiB
YAML
68 lines
2.7 KiB
YAML
name: Powershell Creating Thread Mutex
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id: 637557ec-ca08-11eb-bd0a-acde48001122
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version: 3
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date: '2022-05-02'
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author: Teoderick Contreras, Splunk
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type: TTP
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datamodel: []
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description: The following analytic identifies suspicious PowerShell script execution
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via EventCode 4104 that is using the `mutex` function. This function is commonly
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seen in some obfuscated PowerShell scripts to make sure that only one instance of
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there process is running on a compromise machine. During triage, review parallel
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processes within the same timeframe. Review the full script block to identify other
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related artifacts.
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search: '`powershell` EventCode=4104 ScriptBlockText = "*Threading.Mutex*" | stats count min(_time)
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as firstTime max(_time) as lastTime by EventCode ScriptBlockText Computer UserID | `security_content_ctime(firstTime)`
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| `security_content_ctime(lastTime)` | `powershell_creating_thread_mutex_filter`'
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how_to_implement: To successfully implement this analytic, you will need to enable
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PowerShell Script Block Logging on some or all endpoints. Additional setup here
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https://docs.splunk.com/Documentation/UBA/5.0.4.1/GetDataIn/AddPowerShell#Configure_module_logging_for_PowerShell.
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known_false_positives: powershell developer may used this function in their script
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for instance checking too.
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references:
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- https://isc.sans.edu/forums/diary/Some+Powershell+Malicious+Code/22988/
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- https://docs.splunk.com/Documentation/UBA/5.0.4.1/GetDataIn/AddPowerShell#Configure_module_logging_for_PowerShell.
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- https://blog.palantir.com/tampering-with-windows-event-tracing-background-offense-and-defense-4be7ac62ac63
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- https://static1.squarespace.com/static/552092d5e4b0661088167e5c/t/59c1814829f18782e24f1fe2/1505853768977/Windows+PowerShell+Logging+Cheat+Sheet+ver+Sept+2017+v2.1.pdf
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- https://www.crowdstrike.com/blog/investigating-powershell-command-and-script-logging/
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tags:
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analytic_story:
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- Malicious PowerShell
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confidence: 80
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context:
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- Source:Endpoint
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- Stage:Defense Evasion
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dataset:
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- https://media.githubusercontent.com/media/splunk/attack_data/master/datasets/attack_techniques/T1059.001/powershell_script_block_logging/sbl_xml.log
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impact: 50
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kill_chain_phases:
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- Exploitation
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message: A suspicious powershell script contains Thread Mutex in $ScriptBlockText$ with
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EventCode $EventCode$ in host $Computer$
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mitre_attack_id:
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- T1027
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- T1027.005
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- T1059.001
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observable:
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- name: Computer
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type: Hostname
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role:
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- Victim
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- name: UserID
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type: User
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role:
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- Victim
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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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- ScriptBlockText
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- Computer
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- UserID
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risk_score: 40
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security_domain: endpoint
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asset_type: Endpoint
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