Name:User Discovery With Env Vars PowerShell id:0cdf318b-a0dd-47d7-b257-c621c0247de8 version:3 date:2024-10-17 author:Mauricio Velazco, Splunk status:production type:Hunting Description:The following analytic detects the execution of `powershell.exe` with command-line arguments that use PowerShell environment variables to identify the current logged user. It leverages data from Endpoint Detection and Response (EDR) agents, focusing on process names and command-line executions. This activity is significant as adversaries may use it for situational awareness and Active Directory discovery on compromised endpoints. If confirmed malicious, this behavior could allow attackers to gather critical user information, aiding in further exploitation and lateral movement within the network. 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.process_name="powershell.exe") (Processes.process="*$env:UserName*" OR Processes.process="*[System.Environment]::UserName*") 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)` | `user_discovery_with_env_vars_powershell_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:Administrators or power users may use this command for troubleshooting. References: -https://attack.mitre.org/techniques/T1033/ drilldown_searches:
: tags: analytic_story: - 'Active Directory Discovery' asset_type:Endpoint confidence:50 impact:30 message:System user discovery on $dest$ mitre_attack_id: - 'T1033' observable: name:'dest' type:'Endpoint' - role: - 'Victim' product: - 'Splunk Enterprise' - 'Splunk Enterprise Security' - 'Splunk Cloud' required_fields: - '_time' - 'Processes.dest' - 'Processes.user' - 'Processes.parent_process_name' - 'Processes.parent_process' - 'Processes.original_file_name' - 'Processes.process_name' - 'Processes.process' - 'Processes.process_id' - 'Processes.parent_process_path' - 'Processes.process_path' - 'Processes.parent_process_id' risk_score:15 security_domain:endpoint
