Name:WinRM Spawning a Process id:a081836a-ba4d-11eb-8593-acde48001122 version:3 date:2024-10-17 author:Drew Church, Michael Haag, Splunk status:experimental type:TTP Description:The following analytic detects suspicious processes spawned by WinRM (wsmprovhost.exe). It leverages data from Endpoint Detection and Response (EDR) agents, focusing on specific child processes like cmd.exe, powershell.exe, and others. This activity is significant as it may indicate exploitation attempts of vulnerabilities like CVE-2021-31166, which could lead to system instability or compromise. If confirmed malicious, attackers could execute arbitrary commands, escalate privileges, or maintain persistence, posing a severe threat to the environment. Data_source:
-Sysmon EventID 1
-Windows Event Log Security 4688
-CrowdStrike ProcessRollup2
search:| tstats `security_content_summariesonly` count min(_time) as firstTime max(_time) as lastTime from datamodel=Endpoint.Processes where Processes.parent_process_name=wsmprovhost.exe Processes.process_name IN ("cmd.exe","sh.exe","bash.exe","powershell.exe","pwsh.exe","schtasks.exe","certutil.exe","whoami.exe","bitsadmin.exe","scp.exe") by Processes.dest Processes.user Processes.parent_process Processes.process_name Processes.process Processes.process_id Processes.parent_process_id | `drop_dm_object_name(Processes)` | `security_content_ctime(firstTime)` | `security_content_ctime(lastTime)` | `winrm_spawning_a_process_filter`
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. known_false_positives:Unknown. Add new processes or filter as needed. It is possible system management software may spawn processes from `wsmprovhost.exe`. References: -https://github.com/SigmaHQ/sigma/blob/9b7fb0c0f3af2e53ed483e29e0d0f88ccf1c08ca/rules/windows/process_access/win_susp_shell_spawn_from_winrm.yml -https://www.zerodayinitiative.com/blog/2021/5/17/cve-2021-31166-a-wormable-code-execution-bug-in-httpsys -https://github.com/0vercl0k/CVE-2021-31166/blob/main/cve-2021-31166.py drilldown_searches:
: tags: analytic_story: - 'CISA AA23-347A' - 'Rhysida Ransomware' - 'Unusual Processes' asset_type:Endpoint confidence:50 cve: - 'CVE-2021-31166' impact:50 message:tbd mitre_attack_id: - 'T1190' observable: name:'user' type:'User' - role: - 'Victim' name:'dest' type:'Hostname' - role: - 'Victim' product: - 'Splunk Enterprise' - 'Splunk Enterprise Security' - 'Splunk Cloud' required_fields: - '_time' - 'Processes.dest' - 'Processes.user' - 'Processes.parent_process' - 'Processes.process_name' - 'Processes.process' - 'Processes.process_id' - 'Processes.parent_process_id' risk_score:25 security_domain:endpoint
