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https://github.com/splunk/security_content
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Gowthamaraj rajendran
90 lines
3.9 KiB
YAML
90 lines
3.9 KiB
YAML
name: Malicious PowerShell Process - Encoded Command
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id: c4db14d9-7909-48b4-a054-aa14d89dbb19
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version: 7
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date: '2022-01-18'
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author: David Dorsey, Michael Haag, Splunk
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status: production
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type: Hunting
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description: 'The following analytic identifies the use of the EncodedCommand PowerShell
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parameter. This is typically used by Administrators to run complex scripts, but
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commonly used by adversaries to hide their code. \
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The analytic identifies all variations of EncodedCommand, as PowerShell allows the
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ability to shorten the parameter. For example enc, enco, encod and so forth. In
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addition, through our research it was identified that PowerShell will interpret
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different command switch types beyond the hyphen. We have added endash, emdash,
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horizontal bar, and forward slash. \
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During triage, review parallel events to determine legitimacy. Tune as needed based
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on admin scripts in use. \
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Alternatively, may use regex per matching here https://regexr.com/662ov.'
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data_source:
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- Sysmon Event ID 1
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search: "| tstats `security_content_summariesonly` count min(_time) as firstTime max(_time)\
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\ as lastTime from datamodel=Endpoint.Processes where `process_powershell` by Processes.user\
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\ Processes.process_name Processes.process Processes.parent_process_name Processes.original_file_name\
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\ Processes.dest Processes.process_id | `drop_dm_object_name(Processes)` | `security_content_ctime(firstTime)`\
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\ | `security_content_ctime(lastTime)` | where match(process,\"(?i)[\\-|\\/|\u2013\
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|\u2014|\u2015]e(nc*o*d*e*d*c*o*m*m*a*n*d*)*\\s+[^-]\") | `malicious_powershell_process___encoded_command_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: System administrators may use this option, but it's not common.
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references:
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- https://regexr.com/662ov
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- https://github.com/redcanaryco/AtomicTestHarnesses/blob/master/TestHarnesses/T1059.001_PowerShell/OutPowerShellCommandLineParameter.ps1
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- https://ss64.com/ps/powershell.html
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- https://twitter.com/M_haggis/status/1440758396534214658?s=20
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- https://www.microsoft.com/security/blog/2022/01/15/destructive-malware-targeting-ukrainian-organizations/
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- https://www.microsoft.com/en-us/security/blog/2023/05/24/volt-typhoon-targets-us-critical-infrastructure-with-living-off-the-land-techniques/
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tags:
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analytic_story:
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- Hermetic Wiper
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- Malicious PowerShell
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- NOBELIUM Group
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- WhisperGate
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- DarkCrystal RAT
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- Qakbot
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- CISA AA22-320A
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- Sandworm Tools
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- Data Destruction
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- Volt Typhoon
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asset_type: Endpoint
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confidence: 50
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impact: 70
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message: Powershell.exe running potentially malicious encodede commands on $dest$
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mitre_attack_id:
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- T1027
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observable:
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- name: dest
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type: Endpoint
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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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- Processes.process_name
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- Processes.process
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- Processes.user
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- Processes.parent_process_name
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- Processes.dest
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- Processes.process_id
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risk_score: 35
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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/T1027/atomic_red_team/windows-sysmon.log
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source: XmlWinEventLog:Microsoft-Windows-Sysmon/Operational
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sourcetype: xmlwineventlog
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