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P4T12ICK
66 lines
2.7 KiB
YAML
66 lines
2.7 KiB
YAML
name: WinRM Spawning a Process
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id: a081836a-ba4d-11eb-8593-acde48001122
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version: 1
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date: '2021-05-21'
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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 identifies suspicious processes spawning from
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WinRM (wsmprovhost.exe). This analytic is related to potential exploitation of CVE-2021-31166.
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which is a kernel-mode device driver http.sys vulnerability. Current proof of concept
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code will blue-screen the operating system. However, http.sys used by many different
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Windows processes, including WinRM. In this case, identifying suspicious process
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create (child processes) from `wsmprovhost.exe` is what this analytic is identifying.
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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 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.dest Processes.user Processes.parent_process Processes.process_name
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Processes.process Processes.process_id Processes.parent_process_id | `drop_dm_object_name(Processes)`
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| `security_content_ctime(firstTime)` | `security_content_ctime(lastTime)` | `winrm_spawning_a_process_filter`'
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how_to_implement: To successfully implement this search you need to be ingesting information
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on process that include the name of the process responsible for the changes from
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your endpoints into the `Endpoint` datamodel in the `Processes` node.
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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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tags:
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analytic_story:
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- Unusual Processes
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asset_type: Endpoint
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confidence: 50
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cve:
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- CVE-2021-31166
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impact: 50
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message: tbd
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mitre_attack_id:
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- T1190
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observable:
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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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- name: dest
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type: Hostname
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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.dest
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- Processes.user
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- Processes.parent_process
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- Processes.process_name
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- Processes.process
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- Processes.process_id
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- Processes.parent_process_id
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risk_score: 25
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security_domain: endpoint
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