Name:Windows Rasautou DLL Execution id:6f42b8be-8e96-11ec-ad5a-acde48001122 version:5 date:2024-11-28 author:Michael Haag, Splunk status:production type:TTP Description:The following analytic detects the execution of an arbitrary DLL by the Windows Remote Auto Dialer (rasautou.exe). This behavior is identified by analyzing process creation events where rasautou.exe is executed with specific command-line arguments. This activity is significant because it leverages a Living Off The Land Binary (LOLBin) to execute potentially malicious code, bypassing traditional security controls. If confirmed malicious, this technique could allow an attacker to execute arbitrary code, potentially leading to system compromise, privilege escalation, or persistent access within the environment. 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=rasautou.exe Processes.process="* -d *"AND Processes.process="* -p *" by Processes.dest Processes.user Processes.parent_process_name Processes.process_name Processes.process Processes.process_id Processes.parent_process_id Processes.original_file_name | `drop_dm_object_name(Processes)` | `security_content_ctime(firstTime)` | `security_content_ctime(lastTime)` | `windows_rasautou_dll_execution_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:False positives will be limited to applications that require Rasautou.exe to load a DLL from disk. Filter as needed. References: -https://github.com/mandiant/DueDLLigence -https://github.com/MHaggis/notes/blob/master/utilities/Invoke-SPLDLLigence.ps1 -https://gist.github.com/NickTyrer/c6043e4b302d5424f701f15baf136513 -https://www.mandiant.com/resources/staying-hidden-on-the-endpoint-evading-detection-with-shellcode drilldown_searches: name:'View the detection results for - "$dest$"' search:'%original_detection_search% | search dest = "$dest$"' earliest_offset:'$info_min_time$' latest_offset:'$info_max_time$' name:'View risk events for the last 7 days for - "$dest$"' search:'| from datamodel Risk.All_Risk | search normalized_risk_object IN ("$dest$") 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: - 'Compromised Windows Host' - 'Windows Defense Evasion Tactics' asset_type:Endpoint confidence:100 impact:80 message:An instance of $parent_process_name$ spawning $process_name$ was identified on endpoint $dest$ attempting to load a DLL in a suspicious manner. mitre_attack_id: - 'T1055.001' - 'T1218' - 'T1055' observable: 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:80 security_domain:endpoint
