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Nasreddine Bencherchali
11c909f725
* Add YAML formatting and validation infrastructure - Add yamlfmt configuration (.yamlfmt) with 4-space indent, LF line endings - Add yamllint configuration (.yamllint) for syntax validation (detections/ only) - Add pre-commit hook for automatic YAML formatting - Add CI validation script with unified error output - Add GitHub Actions workflow for PR validation - Add documentation for setup and usage - Support custom yamlfmt binary path via --yamlfmt-path flag * comment yaml check from pre-commit * apply yamlfmt * Update yaml-validation.yml * Update yaml-validation.yml * application folder search formatting * cloud folder search formatting * web folder search formatting * network folder search formatting * endpoint folder search formatting * resolve first conflict * apply formatting * remove additional pipe * Update README.md * update versions * restore and update formatting (#3920) --------- Co-authored-by: Bhavin Patel <bhavin.j.patel91@gmail.com>
56 lines
4.3 KiB
YAML
56 lines
4.3 KiB
YAML
name: Malicious PowerShell Process - Encoded Command
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id: c4db14d9-7909-48b4-a054-aa14d89dbb19
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version: 19
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date: '2026-02-09'
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author: David Dorsey, Michael Haag, Splunk, SirDuckly, GitHub Community
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status: production
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type: Hunting
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description: The following analytic detects the use of the EncodedCommand parameter in PowerShell processes. It leverages Endpoint Detection and Response (EDR) data to identify variations of the EncodedCommand parameter, including shortened forms and different command switch types. This activity is significant because adversaries often use encoded commands to obfuscate malicious scripts, making detection harder. If confirmed malicious, this behavior could allow attackers to execute hidden code, potentially leading to unauthorized access, privilege escalation, or persistent threats within the environment. Review parallel events to determine legitimacy and tune based on known administrative scripts.
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data_source:
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- Sysmon EventID 1
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- Windows Event Log Security 4688
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- CrowdStrike ProcessRollup2
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search: "| tstats `security_content_summariesonly` count min(_time) as firstTime max(_time) as lastTime from datamodel=Endpoint.Processes where `process_powershell` by Processes.action Processes.dest Processes.original_file_name Processes.parent_process Processes.parent_process_exec Processes.parent_process_guid Processes.parent_process_id Processes.parent_process_name Processes.parent_process_path Processes.process Processes.process_exec Processes.process_guid Processes.process_hash Processes.process_id Processes.process_integrity_level Processes.process_name Processes.process_path Processes.user Processes.user_id Processes.vendor_product | `drop_dm_object_name(Processes)` | `security_content_ctime(firstTime)` | `security_content_ctime(lastTime)` | where match(process,\"(?i)[\\-|\\/|–|—|―][Ee^]{1,2}[NnCcOoDdEeMmAa^]+\\s+[\\\"]?[A-Za-z0-9+/=]{5,}[\\\"]?\") | `malicious_powershell_process___encoded_command_filter`"
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how_to_implement: The detection is based on data that originates from Endpoint Detection and Response (EDR) agents. These agents are designed to provide security-related telemetry from the endpoints where the agent is installed. To implement this search, you must ingest logs that contain the process GUID, process name, and parent process. Additionally, you must ingest complete command-line executions. These logs must be processed using the appropriate Splunk Technology Add-ons that are specific to the EDR product. The logs must also be mapped to the `Processes` node of the `Endpoint` data model. Use the Splunk Common Information Model (CIM) to normalize the field 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/Windows/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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- SolarWinds WHD RCE Post Exploitation
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- CISA AA22-320A
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- Hermetic Wiper
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- Sandworm Tools
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- Qakbot
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- Volt Typhoon
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- NOBELIUM Group
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- Data Destruction
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- Lumma Stealer
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- Malicious PowerShell
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- DarkCrystal RAT
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- WhisperGate
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- Crypto Stealer
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- Microsoft SharePoint Vulnerabilities
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- Scattered Spider
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- GhostRedirector IIS Module and Rungan Backdoor
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- Microsoft WSUS CVE-2025-59287
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asset_type: Endpoint
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mitre_attack_id:
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- T1027
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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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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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