Name:Windows Powershell RemoteSigned File id:f7f7456b-470d-4a95-9703-698250645ff4 version:3 date:2024-09-30 author:Teoderick Contreras, Splunk status:production type:Anomaly Description:The following analytic identifies the use of the "remotesigned" execution policy for PowerShell scripts. It leverages data from Endpoint Detection and Response (EDR) agents, focusing on command-line executions containing "remotesigned" and "-File". This activity is significant because the "remotesigned" policy allows locally created scripts to run without restrictions, posing a potential security risk. If confirmed malicious, an attacker could execute unauthorized scripts, leading to code execution, privilege escalation, or persistence within the environment. Data_source:
-Sysmon EventID 1
-Windows Event Log Security 4688
-CrowdStrike ProcessRollup2
search:| tstats `security_content_summariesonly` min(_time) as firstTime max(_time) as lastTime from datamodel=Endpoint.Processes where `process_powershell` Processes.process="* remotesigned *" Processes.process="* -File *" by Processes.dest Processes.user Processes.parent_process Processes.process_name Processes.original_file_name Processes.process Processes.process_id Processes.parent_process_id | `drop_dm_object_name(Processes)` | `security_content_ctime(firstTime)` | `security_content_ctime(lastTime)` | `windows_powershell_remotesigned_file_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:It is possible administrators or scripts may run these commands, filtering may be required. References: -https://learn.microsoft.com/en-us/powershell/module/microsoft.powershell.security/set-executionpolicy?view=powershell-7.3 drilldown_searches: name:'View the detection results for - "$dest$" and "$user$"' search:'%original_detection_search% | search dest = "$dest$" user = "$user$"' earliest_offset:'$info_min_time$' latest_offset:'$info_max_time$' name:'View risk events for the last 7 days for - "$dest$" and "$user$"' search:'| from datamodel Risk.All_Risk | search normalized_risk_object IN ("$dest$", "$user$") 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: - 'Amadey' asset_type:Endpoint confidence:50 impact:50 message:A PowerShell commandline with remotesigned policy executed on $dest$ mitre_attack_id: - 'T1059.001' - 'T1059' observable: name:'dest' type:'Hostname' - role: - 'Victim' name:'user' type:'User' - role: - 'Victim' product: - 'Splunk Enterprise' - 'Splunk Enterprise Security' - 'Splunk Cloud' risk_score:25 required_fields: - '_time' - 'Processes.dest' - 'Processes.user' - 'Processes.parent_process' - 'Processes.process_name' - 'Processes.original_file_name' - 'Processes.process' - 'Processes.process_id' - 'Processes.parent_process_id' security_domain:endpoint
