Name:Windows WSUS Spawning Shell id:76ea28ac-6f10-43fd-b5fe-340022ad0fd3 version:1 date:2025-10-24 author:Michael Haag, Splunk status:production type:TTP Description:The following analytic identifies instances where a shell (PowerShell.exe or Cmd.exe) is spawned from wsusservice.exe, the Windows Server Update Services process. This detection leverages data from Endpoint Detection and Response (EDR) agents, focusing on process creation events where the parent process is wsusservice.exe. This activity is significant as it may indicate exploitation of CVE-2025-59287, a critical deserialization vulnerability in WSUS that allows unauthenticated remote code execution. If confirmed malicious, this behavior could allow attackers to execute arbitrary commands on WSUS servers, potentially leading to system compromise, data exfiltration, domain enumeration, or further lateral movement within the network. Data_source:
-Sysmon EventID 1
-Windows Event Log Security 4688
-CrowdStrike ProcessRollup2
search:| tstats `security_content_summariesonly` count values(Processes.process_name) as process_name values(Processes.process) as process min(_time) as firstTime max(_time) as lastTime from datamodel=Endpoint.Processes where Processes.parent_process_name=wsusservice.exe AND `process_cmd` OR `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)`| `windows_wsus_spawning_shell_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:Legitimate WSUS maintenance scripts or administrative tools may spawn shells in rare cases. However, wsusservice.exe spawning interactive shells is highly abnormal behavior. Review the command line arguments and user context to determine legitimacy. Filter known administrative scripts if needed. References: -https://www.huntress.com/blog/exploitation-of-windows-server-update-services-remote-code-execution-vulnerability -https://msrc.microsoft.com/update-guide/vulnerability/CVE-2025-59287 -https://hawktrace.com/blog/CVE-2025-59287-UNAUTH drilldown_searches: name:'View the detection results for - "$dest$"' search:'%original_detection_search% | search dest = "$dest$"' earliest_offset:'$info_min_time$' latest_offset:'$info_max_time$' name:'View risk events for the last 7 days for - "$dest$"' search:'| from datamodel Risk.All_Risk | search normalized_risk_object IN ("$dest$") starthoursago=168 | stats count min(_time) as firstTime max(_time) as lastTime values(search_name) as "Search Name" values(risk_message) as "Risk Message" values(analyticstories) as "Analytic Stories" values(annotations._all) as "Annotations" values(annotations.mitre_attack.mitre_tactic) as "ATT&CK Tactics" by normalized_risk_object | `security_content_ctime(firstTime)` | `security_content_ctime(lastTime)`' earliest_offset:'$info_min_time$' latest_offset:'$info_max_time$' tags: analytic_story: - 'Microsoft WSUS CVE-2025-59287' asset_type:Endpoint cve: - 'CVE-2025-59287' mitre_attack_id: - 'T1190' - 'T1505.003' product: - 'Splunk Enterprise' - 'Splunk Enterprise Security' - 'Splunk Cloud' security_domain:endpoint
