Name:Regsvr32 Silent and Install Param Dll Loading id:f421c250-24e7-11ec-bc43-acde48001122 version:4 date:2024-09-30 author:Teoderick Contreras, Splunk status:production type:Anomaly Description:The following analytic detects the loading of a DLL using the regsvr32 application with the silent parameter and DLLInstall execution. It leverages data from Endpoint Detection and Response (EDR) agents, focusing on process command-line arguments and parent process details. This activity is significant as it is commonly used by RAT malware like Remcos and njRAT to load malicious DLLs on compromised machines. If confirmed malicious, this technique could allow attackers to execute arbitrary code, maintain persistence, and further compromise the system. 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 `process_regsvr32` AND Processes.process="*/i*" by Processes.dest Processes.parent_process Processes.process Processes.parent_process_name Processes.process_name Processes.original_file_name Processes.user | `drop_dm_object_name(Processes)` | `security_content_ctime(firstTime)` | `security_content_ctime(lastTime)` | where match(process,"(?i)[\-|\/][Ss]{1}") | `regsvr32_silent_and_install_param_dll_loading_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:Other third part application may used this parameter but not so common in base windows environment. References: -https://app.any.run/tasks/dc93ee63-050c-4ff8-b07e-8277af9ab939/ -https://attack.mitre.org/techniques/T1218/010/ drilldown_searches: 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)`' earliest_offset:'$info_min_time$' latest_offset:'$info_max_time$' tags: analytic_story: - 'AsyncRAT' - 'Hermetic Wiper' - 'Living Off The Land' - 'Data Destruction' - 'Remcos' - 'Suspicious Regsvr32 Activity' asset_type:Endpoint confidence:60 impact:60 message:An instance of $parent_process_name$ spawning $process_name$ was identified on endpoint $dest$ by user $user$ attempting to load a DLL using the silent and dllinstall parameter. mitre_attack_id: - 'T1218' - 'T1218.010' observable: name:'user' type:'User' - role: - 'Victim' name:'dest' type:'Hostname' - role: - 'Victim' name:'parent_process_name' type:'Process' - role: - 'Attacker' name:'process_name' type:'Process' - role: - 'Attacker' 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:36 security_domain:endpoint
