Name:Rundll32 Process Creating Exe Dll Files id:6338266a-ee2a-11eb-bf68-acde48001122 version:4 date:2024-09-30 author:Teoderick Contreras, Splunk status:production type:TTP Description:The following analytic detects a rundll32 process creating executable (.exe) or dynamic link library (.dll) files. It leverages Sysmon EventCode 11 to identify instances where rundll32.exe generates these file types. This activity is significant because rundll32 is often exploited by malware, such as IcedID, to drop malicious payloads in directories like Temp, AppData, or ProgramData. If confirmed malicious, this behavior could allow an attacker to execute arbitrary code, establish persistence, or escalate privileges within the environment. Data_source:
-Sysmon EventID 11
search:`sysmon` EventCode=11 Image="*rundll32.exe" TargetFilename IN ("*.exe", "*.dll") | stats count min(_time) as firstTime max(_time) as lastTime by Image TargetFilename Computer | rename Computer as dest | rename TargetFilename as file_name | `security_content_ctime(firstTime)` | `security_content_ctime(lastTime)` | `rundll32_process_creating_exe_dll_files_filter`
how_to_implement:To successfully implement this search, you need to be ingesting logs with the process name, TargetFilename, and eventcode 11 executions from your endpoints. If you are using Sysmon, you must have at least version 6.0.4 of the Sysmon TA. Tune and filter known instances where renamed rundll32.exe may be used. known_false_positives:unknown References: -https://any.run/malware-trends/icedid 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: - 'IcedID' - 'Living Off The Land' asset_type:Endpoint confidence:100 impact:80 message:rundll32 process drops a file $file_name$ on host $dest$ mitre_attack_id: - 'T1218' - 'T1218.011' observable: name:'dest' type:'Hostname' - role: - 'Victim' name:'file_name' type:'File Name' - role: - 'Attacker' product: - 'Splunk Enterprise' - 'Splunk Enterprise Security' - 'Splunk Cloud' required_fields: - '_time' - 'process_name' - 'file_name' - 'process_guid' - 'dest' - 'user_id' risk_score:80 security_domain:endpoint
