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https://github.com/splunk/security_content
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Bhavin Patel
63 lines
2.6 KiB
YAML
63 lines
2.6 KiB
YAML
name: Suspicious Powershell Command-Line Arguments
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id: 2cdb91d2-542c-497f-b252-be495e71f38c
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version: 8
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date: '2024-10-17'
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author: David Dorsey, Splunk
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status: deprecated
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type: TTP
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description: This search looks for PowerShell processes started with a base64 encoded
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command-line passed to it, with parameters to modify the execution policy for the
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process, and those that prevent the display of an interactive prompt to the user.
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This combination of command-line options is suspicious because it overrides the
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default PowerShell execution policy, attempts to hide itself from the user, and
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passes an encoded script to be run on the command-line. Deprecated because almost
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the same as Malicious PowerShell Process - Encoded Command
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data_source:
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- Sysmon EventID 1
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search: '| tstats `security_content_summariesonly` count values(Processes.process)
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as process values(Processes.parent_process) as parent_process min(_time) as firstTime
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max(_time) as lastTime from datamodel=Endpoint.Processes where Processes.process_name=powershell.exe
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by Processes.user Processes.process_name Processes.parent_process_name Processes.dest |
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`drop_dm_object_name(Processes)` | `security_content_ctime(firstTime)`| `security_content_ctime(lastTime)`|
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search (process=*-EncodedCommand* OR process=*-enc*) process=*-Exec* | `suspicious_powershell_command_line_arguments_filter`'
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how_to_implement: The detection is based on data that originates from Endpoint Detection
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and Response (EDR) agents. These agents are designed to provide security-related
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telemetry from the endpoints where the agent is installed. To implement this search,
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you must ingest logs that contain the process GUID, process name, and parent process.
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Additionally, you must ingest complete command-line executions. These logs must
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be processed using the appropriate Splunk Technology Add-ons that are specific to
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the EDR product. The logs must also be mapped to the `Processes` node of the `Endpoint`
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data model. Use the Splunk Common Information Model (CIM) to normalize the field
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names and speed up the data modeling process.
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known_false_positives: Legitimate process can have this combination of command-line
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options, but it's not common.
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references: []
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tags:
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analytic_story:
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- Malicious PowerShell
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- Hermetic Wiper
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- CISA AA22-320A
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asset_type: Endpoint
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confidence: 50
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impact: 50
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message: tbd
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mitre_attack_id:
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- T1059.001
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observable:
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- name: dest
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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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risk_score: 25
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security_domain: endpoint
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