Windows Potential AppDomainManager Hijack Artifacts Creation

name: Windows Potential AppDomainManager Hijack Artifacts Creation
id: be19b369-fd0c-42be-ae97-c10b6c01638f
version: 4
date: '2026-04-15'
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)

    | eval exe_files = mvfilter(match(file_name, "\.exe$") AND NOT match(file_name, "\.exe\.config$"))
    | eval config_files = mvfilter(match(file_name, "\.exe\.config$"))
    | eval exe_base_names = mvmap(exe_files, replace(exe_files, "\.exe$", ""))
    | eval config_base_names = mvmap(config_files, replace(config_files, "\.exe\.config$", ""))

    | mvexpand exe_base_names
    | mvexpand config_base_names

    | eval file_count = mvcount(file_name)

    | 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"
rba:
    message: Potential Windows AppDomainManager hijack artifact files created on [$dest$]
    risk_objects:
        - field: dest
          type: system
          score: 20
    threat_objects:
        - field: file_name
          type: file_name
        - field: file_path
          type: file_path
tags:
    analytic_story:
        - SesameOp
    asset_type: Endpoint
    mitre_attack_id:
        - T1574.014
    product:
        - Splunk Enterprise
        - Splunk Enterprise Security
        - Splunk Cloud
    security_domain: endpoint
tests:
    - name: True Positive Test
      attack_data:
        - data: https://media.githubusercontent.com/media/splunk/attack_data/master/datasets/attack_techniques/T1574.014/appdomain_hijack_artifacts/appdomain_hijack.log
          source: XmlWinEventLog:Microsoft-Windows-Sysmon/Operational
          sourcetype: XmlWinEventLog