Name:Windows Potential AppDomainManager Hijack Artifacts Creation id:be19b369-fd0c-42be-ae97-c10b6c01638f version:5 date:None author:Teoderick Contreras, Splunk status:production type:Anomaly Description:The following analytic detects the creation of an .exe file along with its corresponding .exe.config and a .dll in the same directory, which is a common pattern indicative of potential AppDomain hijacking or CLR code injection attempts. This behavior may signal that a malicious actor is attempting to load a rogue assembly into a legitimate application's AppDomain, allowing code execution under the context of a trusted process. Data_source:
-Sysmon EventID 11
search:| tstats `security_content_summariesonly` count min(_time) AS firstTime max(_time) AS lastTime from datamodel=Endpoint.Filesystem where Filesystem.file_name IN ("*.exe", "*.exe.config", "*.dll") AND Filesystem.file_path IN ("*\\windows\\fonts\\*", "*\\temp\\*", "*\\users\\public\\*", "*\\windows\\debug\\*","*\\Users\\Administrator\\Music\\*", "*\\Windows\\servicing\\*", "*\\Users\\Default\\*", "*Recycle.bin*", "*\\Windows\\Media\\*", "*\\Windows\\repair\\*", "*\\PerfLogs\\*") AND Filesystem.action = "created" by Filesystem.action Filesystem.dest Filesystem.file_access_time Filesystem.file_create_time Filesystem.file_hash Filesystem.file_modify_time Filesystem.file_name Filesystem.file_path Filesystem.file_acl Filesystem.file_size Filesystem.process_guid Filesystem.process_id Filesystem.user Filesystem.vendor_product | `drop_dm_object_name("Filesystem")` | stats values(file_name) AS file_name values(file_path) AS file_path values(user) AS user min(firstTime) AS firstTime max(lastTime) AS lastTime BY dest process_guid | eval exe_present = if(mvcount(mvfilter(match(file_name, "\.exe$"))) > 0, 1, 0) | eval config_present = if(mvcount(mvfilter(match(file_name, "\.exe\.config$"))) > 0, 1, 0) | eval dll_present = if(mvcount(mvfilter(match(file_name, "\.dll$"))) > 0, 1, 0)
| where file_count >= 3 AND exe_present = 1 AND config_present = 1 AND dll_present = 1 AND exe_base_names = config_base_names | `security_content_ctime(firstTime)` | `security_content_ctime(lastTime)` | `windows_potential_appdomainmanager_hijack_artifacts_creation_filter`
how_to_implement:To successfully implement this search you need to be ingesting information on process that include the name of the process responsible for the changes from your endpoints into the `Endpoint` datamodel in the `Filesystem` node. In addition, confirm the latest CIM App 4.20 or higher is installed and the latest TA for the endpoint product. known_false_positives:This detection may still produce false positives, so additional filtering is recommended. To validate potential alerts, verify that the executable’s original file name matches its current file name, and also review the associated .config file to confirm which DLLs are expected to load during execution. This helps distinguish legitimate activity from suspicious behavior. References: -https://www.microsoft.com/en-us/security/blog/2025/11/03/sesameop-novel-backdoor-uses-openai-assistants-api-for-command-and-control/ -https://attack.mitre.org/techniques/T1574/014/ -https://gist.github.com/djhohnstein/afb93a114b848e16facf0b98cd7cb57b -https://www.scworld.com/brief/appdomain-manager-injection-exploited-for-cobalt-strike-beacon-delivery -https://jp.security.ntt/insights_resources/tech_blog/appdomainmanager-injection-en/ drilldown_searches: name:'View the detection results for - "$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$") | 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:'7d' latest_offset:'0' analytic_story:['SesameOp']
