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50 lines
2.4 KiB
YAML
50 lines
2.4 KiB
YAML
name: Powershell Processing Stream Of Data
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id: 0d718b52-c9f1-11eb-bc61-acde48001122
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version: 1
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date: '2021-06-10'
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author: Teoderick Contreras, Splunk
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type: batch
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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 processing compressed stream data. This is typically
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found in obfuscated PowerShell or PowerShell executing embedded .NET or binary files
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that are stream flattened and will be deflated durnig execution. During triage,
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review parallel processes within the same timeframe. Review the full script block
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to identify other related artifacts.
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search: '`powershell` EventCode=4104 Message = "*IO.Compression.*" OR Message = "*IO.StreamReader*"
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OR Message = "*]::Decompress*" | stats count min(_time) as firstTime max(_time)
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as lastTime by EventCode Message ComputerName User | `security_content_ctime(firstTime)`
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| `security_content_ctime(lastTime)` | `powershell_processing_stream_of_data_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 may used this function to process compressed data.
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references:
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- https://medium.com/@ahmedjouini99/deobfuscating-emotets-powershell-payload-e39fb116f7b9
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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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automated_detection_testing: passed
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dataset:
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- https://media.githubusercontent.com/media/splunk/attack_data/master/datasets/honeypots/pwsh/windows-powershell.log
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kill_chain_phases:
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- Exploitation
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mitre_attack_id:
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- T1059.001
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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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- Message
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- ComputerName
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- User
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- Score
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security_domain: endpoint
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