Name:Windows MsMpEng Writing to System32 id:dc615235-1241-411a-b170-b34a4c8924aa version:1 date:None author:Raven Tait, Splunk status:production type:TTP Description:Detects MsMpEng.exe creating a file in C:\\Windows\\System32\\.
This should never happen under normal operation Windows Defender does not install kernel drivers at runtime.
In the BlueHammer exploit, the TOCTOU race causes MsMpEng (SYSTEM) to write the attacker's driver payload directly into the drivers directory. Data_source:
-Sysmon EventID 15
-Sysmon EventID 11
search:`sysmon` (EventID=15 OR EventID=11) Image="*\\MsMpEng.exe" TargetFilename="*:\\Windows\\System32\\*" | fillnull | stats count min(_time) as firstTime max(_time) as lastTime by Computer Image TargetFilename EventID dest dvc file_hash file_name file_path action process_exec process_guid process_id process_name process_path signature signature_id user_id vendor_product | `security_content_ctime(firstTime)` | `security_content_ctime(lastTime)` | `windows_msmpeng_writing_to_system32_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:No false positives have been identified at this time. References: -https://github.com/Nightmare-Eclipse/BlueHammer drilldown_searches: earliest_offset:'$info_min_time$' latest_offset:'$info_max_time$' name:'View the detection results for - "$user$" and "$dest$"' search:'%original_detection_search% | search user = "$user$" dest = "$dest$"' earliest_offset:'$info_min_time$' latest_offset:'$info_max_time$' name:'View risk events for the last 7 days for - "$user$" and "$dest$"' search:'| from datamodel Risk.All_Risk | search normalized_risk_object IN ("$user$", "$dest$") 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)`' analytic_story:['Windows Drivers', 'Windows Privilege Escalation', 'BlueHammer', 'RedSun']
