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Eric
69 lines
3.5 KiB
YAML
69 lines
3.5 KiB
YAML
name: WinRM Spawning a Process
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id: a081836a-ba4d-11eb-8593-acde48001122
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version: 6
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date: '2025-05-02'
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author: Drew Church, Michael Haag, Splunk
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status: experimental
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type: TTP
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description: The following analytic detects suspicious processes spawned by WinRM
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(wsmprovhost.exe). It leverages data from Endpoint Detection and Response (EDR)
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agents, focusing on specific child processes like cmd.exe, powershell.exe, and others.
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This activity is significant as it may indicate exploitation attempts of vulnerabilities
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like CVE-2021-31166, which could lead to system instability or compromise. If confirmed
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malicious, attackers could execute arbitrary commands, escalate privileges, or maintain
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persistence, posing a severe threat to the environment.
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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)
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as lastTime from datamodel=Endpoint.Processes where Processes.parent_process_name=wsmprovhost.exe
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Processes.process_name IN ("cmd.exe","sh.exe","bash.exe","powershell.exe","pwsh.exe","schtasks.exe","certutil.exe","whoami.exe","bitsadmin.exe","scp.exe")
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by Processes.action Processes.dest Processes.original_file_name Processes.parent_process
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Processes.parent_process_exec Processes.parent_process_guid Processes.parent_process_id
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Processes.parent_process_name Processes.parent_process_path Processes.process Processes.process_exec
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Processes.process_guid Processes.process_hash Processes.process_id Processes.process_integrity_level
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Processes.process_name Processes.process_path Processes.user Processes.user_id Processes.vendor_product
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| `drop_dm_object_name(Processes)` | `security_content_ctime(firstTime)` | `security_content_ctime(lastTime)`
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| `winrm_spawning_a_process_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: Unknown. Add new processes or filter as needed. It is possible
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system management software may spawn processes from `wsmprovhost.exe`.
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references:
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- https://github.com/SigmaHQ/sigma/blob/9b7fb0c0f3af2e53ed483e29e0d0f88ccf1c08ca/rules/windows/process_access/win_susp_shell_spawn_from_winrm.yml
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- https://www.zerodayinitiative.com/blog/2021/5/17/cve-2021-31166-a-wormable-code-execution-bug-in-httpsys
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- https://github.com/0vercl0k/CVE-2021-31166/blob/main/cve-2021-31166.py
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rba:
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message: winrm.exe spawning a process observed on $dest$
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risk_objects:
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- field: user
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type: user
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score: 25
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- field: dest
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type: system
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score: 25
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threat_objects: []
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tags:
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analytic_story:
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- CISA AA23-347A
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- Rhysida Ransomware
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- Unusual Processes
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asset_type: Endpoint
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cve:
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- CVE-2021-31166
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mitre_attack_id:
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- T1190
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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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