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tccontre
77 lines
3.1 KiB
YAML
77 lines
3.1 KiB
YAML
name: Powershell Fileless Process Injection via GetProcAddress
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id: a26d9db4-c883-11eb-9d75-acde48001122
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version: 1
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date: '2021-06-08'
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author: Michael Haag, Splunk
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type: TTP
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datamodel: []
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description: 'The following analytic utilizes PowerShell Script Block Logging (EventCode=4104)
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to identify suspicious PowerShell execution. Script Block Logging captures the command
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sent to PowerShell, the full command to be executed. Upon enabling, logs will output
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to Windows event logs. Dependent upon volume, enable no critical endpoints or all.
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\
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This analytic identifies `GetProcAddress` in the script block. This is not normal
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to be used by most PowerShell scripts and is typically unsafe/malicious. Many attack
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toolkits use GetProcAddress to obtain code execution. \
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In use, `$var_gpa = $var_unsafe_native_methods.GetMethod(GetProcAddress` and later
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referenced/executed elsewhere. \
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During triage, review parallel processes using an EDR product or 4688 events. It
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will be important to understand the timeline of events around this activity. Review
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the entire logged PowerShell script block.'
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search: '`powershell` EventCode=4104 Message=*getprocaddress* | stats count min(_time)
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as firstTime max(_time) as lastTime by OpCode ComputerName User EventCode Message
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| `security_content_ctime(firstTime)` | `security_content_ctime(lastTime)` | `powershell_fileless_process_injection_via_getprocaddress_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: Limited false positives. Filter as needed.
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references:
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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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confidence: 80
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context:
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- source:endpoint
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- stage: recon
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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/windows-powershell.log
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impact: 60
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kill_chain_phases:
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- Exploitation
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message: A suspicious powershell script contains GetProcAddress API in $Message$
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with EventCode $EventCode$ in host $ComputerName$
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mitre_attack_id:
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- T1059
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- T1055
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- T1059.001
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observable:
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- name: ComputerName
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type: Hostname
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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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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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- Message
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- OpCode
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- ComputerName
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- User
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- EventCode
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risk_score: 48
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security_domain: endpoint
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