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P4T12ICK
67 lines
2.5 KiB
YAML
67 lines
2.5 KiB
YAML
name: Windows Powershell Cryptography Namespace
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id: f8b482f4-6d62-49fa-a905-dfa15698317b
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version: 1
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date: '2023-01-26'
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author: Teoderick Contreras, Splunk
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status: production
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type: Anomaly
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description: The following analytic identifies suspicious PowerShell script execution
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via EventCode 4104 that is processing cryptography namespace library. This technique
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was seen in several powershell malware, loader, downloader and stager that will
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decrypt or decode the next malicious stager or the actual payload. This Anomaly
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detection can be a good indicator that a powershell process to decrypt code. We
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recommend to further check the parent_process_name, the file or data it tries to
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decrypt, network connection and user who execute the script.
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data_source:
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- Powershell 4104
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search: '`powershell` EventCode=4104 ScriptBlockText = "*System.Security.Cryptography*"
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AND NOT(ScriptBlockText IN ("*SHA*", "*MD5*", "*DeriveBytes*")) | stats count min(_time)
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as firstTime max(_time) as lastTime by EventCode ScriptBlockText Computer UserID
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| `security_content_ctime(firstTime)` | `security_content_ctime(lastTime)` | `windows_powershell_cryptography_namespace_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: False positives should be limited. Filter as needed.
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references:
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- https://malpedia.caad.fkie.fraunhofer.de/details/win.asyncrat
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tags:
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analytic_story:
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- AsyncRAT
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asset_type: Endpoint
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confidence: 50
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impact: 50
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message: A suspicious powershell script contains cryptography command in $ScriptBlockText$
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with EventCode $EventCode$ in host $Computer$
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mitre_attack_id:
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- T1059.001
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- T1059
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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: 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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- ScriptBlockText
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- Opcode
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- Computer
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- UserID
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- EventCodes
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risk_score: 25
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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/attack_techniques/T1059.001/asyncrat_crypto_pwh_namespace/windows-powershell-xml.log
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source: XmlWinEventLog:Microsoft-Windows-PowerShell/Operational
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sourcetype: xmlwineventlog
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update_timestamp: true
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