Name:Windows PowerShell ScheduleTask id:ddf82fcb-e9ee-40e3-8712-a50b5bf323fc version:3 date:2024-09-30 author:Michael Haag, Splunk status:production type:Anomaly Description:The following analytic detects potential malicious activities involving PowerShell's task scheduling cmdlets. It leverages PowerShell Script Block Logging (EventCode 4104) to identify unusual or suspicious use of cmdlets like 'New-ScheduledTask' and 'Set-ScheduledTask'. This activity is significant as attackers often use these cmdlets for persistence and remote execution of malicious code. If confirmed malicious, this could allow attackers to maintain access, deliver additional payloads, or execute ransomware, leading to data theft or other severe impacts. Immediate investigation and mitigation are crucial to prevent further compromise. Data_source:
-Powershell Script Block Logging 4104
search:`powershell` EventCode=4104 ScriptBlockText IN ("*New-ScheduledTask*", "*New-ScheduledTaskAction*", "*New-ScheduledTaskSettingsSet*", "*New-ScheduledTaskTrigger*", "*Register-ClusteredScheduledTask*", "*Register-ScheduledTask*", "*Set-ClusteredScheduledTask*", "*Set-ScheduledTask*", "*Start-ScheduledTask*", "*Enable-ScheduledTask*") | stats count min(_time) as firstTime max(_time) as lastTime by EventCode ScriptBlockText Computer user_id | `security_content_ctime(firstTime)` | `security_content_ctime(lastTime)` | `windows_powershell_scheduletask_filter`
how_to_implement:To successfully implement this analytic, you will need to enable PowerShell Script Block Logging on some or all endpoints. Additional setup here https://docs.splunk.com/Documentation/UBA/5.0.4.1/GetDataIn/AddPowerShell#Configure_module_logging_for_PowerShell. known_false_positives:Benign administrative tasks can also trigger alerts, necessitating a firm understanding of the typical system behavior and precise tuning of the analytic to reduce false positives. References: -https://learn.microsoft.com/en-us/powershell/module/scheduledtasks/?view=windowsserver2022-ps -https://thedfirreport.com/2023/06/12/a-truly-graceful-wipe-out/ drilldown_searches: name:'View the detection results for - "$Computer$" and "$user_id$"' search:'%original_detection_search% | search Computer = "$Computer$" user_id = "$user_id$"' earliest_offset:'$info_min_time$' latest_offset:'$info_max_time$' name:'View risk events for the last 7 days for - "$Computer$" and "$user_id$"' search:'| from datamodel Risk.All_Risk | search normalized_risk_object IN ("$Computer$", "$user_id$") 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: - 'Scheduled Tasks' asset_type:Endpoint atomic_guid: - 'af9fd58f-c4ac-4bf2-a9ba-224b71ff25fd' confidence:50 impact:50 message:The PowerShell cmdlets related to task creation, modification and start occurred on $Computer$ by $user_id$. mitre_attack_id: - 'T1053.005' - 'T1059.001' - 'T1059' observable: name:'Computer' type:'Hostname' - role: - 'Victim' name:'user_id' type:'User' - role: - 'Victim' product: - 'Splunk Enterprise' - 'Splunk Enterprise Security' - 'Splunk Cloud' required_fields: - '_time' - 'ScriptBlockText' - 'Computer' - 'EventCode' security_domain:endpoint risk_score:25
