Name:Powershell Remove Windows Defender Directory id:adf47620-79fa-11ec-b248-acde48001122 version:17 date:None author:Teoderick Contreras, Splunk status:production type:Anomaly Description:The following analytic detects a suspicious PowerShell command attempting to delete the Windows Defender directory.
It leverages PowerShell Script Block Logging to identify commands containing "rmdir" and targeting the Windows Defender path.
This activity is significant as it may indicate an attempt to disable or corrupt Windows Defender, a key security component.
If confirmed malicious, this action could allow an attacker to bypass endpoint protection, facilitating further malicious activities without detection. Data_source:
-Powershell Script Block Logging 4104
search:`powershell` EventCode=4104 ScriptBlockText = "*rmdir *" ScriptBlockText = "*\\Microsoft\\Windows Defender*" | fillnull | stats count min(_time) as firstTime max(_time) as lastTime by dest signature signature_id user_id vendor_product EventID Guid Opcode Name Path ProcessID ScriptBlockId ScriptBlockText | `security_content_ctime(firstTime)` | `security_content_ctime(lastTime)` | `powershell_remove_windows_defender_directory_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://help.splunk.com/en/security-offerings/splunk-user-behavior-analytics/get-data-in/5.4.1/add-other-data-to-splunk-uba/configure-powershell-logging-to-see-powershell-anomalies-in-splunk-uba. known_false_positives:No false positives have been identified at this time. References: -https://www.microsoft.com/security/blog/2022/01/15/destructive-malware-targeting-ukrainian-organizations/ drilldown_searches: name:'View the detection results for - "$Computer$" and "$user$"' search:'%original_detection_search% | search Computer = "$Computer$" user = "$user$"' earliest_offset:'$info_min_time$' latest_offset:'$info_max_time$' name:'View risk events for the last 7 days for - "$Computer$" and "$user$"' search:'| from datamodel Risk.All_Risk | search normalized_risk_object IN ("$Computer$", "$user$") | 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:'7d' latest_offset:'0' analytic_story:['Data Destruction', 'WhisperGate']
