Name:UAC Bypass MMC Load Unsigned Dll id:7f04349c-e30d-11eb-bc7f-acde48001122 version:3 date:2024-09-30 author:Teoderick Contreras, Splunk status:production type:TTP Description:The following analytic detects the loading of an unsigned DLL by the MMC.exe application, which is indicative of a potential UAC bypass or privilege escalation attempt. It leverages Sysmon EventCode 7 to identify instances where MMC.exe loads a non-Microsoft, unsigned DLL. This activity is significant because attackers often use this technique to modify CLSID registry entries, causing MMC.exe to load malicious DLLs, thereby bypassing User Account Control (UAC) and gaining elevated privileges. If confirmed malicious, this could allow an attacker to execute arbitrary code with higher privileges, leading to further system compromise and persistence. Data_source:
-Sysmon EventID 7
search:`sysmon` EventCode=7 ImageLoaded = "*.dll" Image = "*\\mmc.exe" Signed=false Company != "Microsoft Corporation" | stats count min(_time) as firstTime max(_time) as lastTime by Image ImageLoaded Signed ProcessId OriginalFileName dest EventCode Company | `security_content_ctime(firstTime)` | `security_content_ctime(lastTime)` | `uac_bypass_mmc_load_unsigned_dll_filter`
how_to_implement:To successfully implement this search, you need to be ingesting logs with the process name and imageloaded executions from your endpoints. If you are using Sysmon, you must have at least version 6.0.4 of the Sysmon TA. known_false_positives:unknown. all of the dll loaded by mmc.exe is microsoft signed dll. References: -https://offsec.almond.consulting/UAC-bypass-dotnet.html 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: - 'Windows Defense Evasion Tactics' asset_type:Endpoint confidence:90 impact:70 message:Suspicious unsigned $ImageLoaded$ loaded by $Image$ on endpoint $dest$ with EventCode $EventCode$ mitre_attack_id: - 'T1548.002' - 'T1548' - 'T1218.014' observable: name:'dest' type:'Hostname' - role: - 'Victim' product: - 'Splunk Enterprise' - 'Splunk Enterprise Security' - 'Splunk Cloud' required_fields: - '_time' - 'Image' - 'ImageLoaded' - 'Signed' - 'ProcessId' - 'OriginalFileName' - 'dest' - 'EventCode' - 'Company' risk_score:63 security_domain:endpoint
