Windows Disable Internet Explorer Addons

SPLUNK detection rule by Teoderick Contreras, Splunk · Apache-2.0

The following analytic detects the execution of iexplore.exe (Internet Explorer) with the -extoff command-line flag, which disables all browser extensions. This flag is commonly abused by adversaries to launch a clean browser session that bypasses security controls such as antivirus browser extensions, toolbars, or group policy-enforced add-ons. Malicious documents or scripts may leverage iexplore.exe -extoff to open phishing pages, command-and-control interfaces, or download additional payloads in an environment free from security monitoring plugins. While this flag may be used legitimately by IT administrators for troubleshooting purposes, its use in modern enterprise environments is rare and should be considered suspicious—particularly when launched by Office applications, scripting engines (e.g., PowerShell, WScript), or scheduled tasks.

name: Windows Disable Internet Explorer Addons
id: 65224d8b-b95d-44ec-bb44-408d830c1258
version: 5
creation_date: '2025-05-28'
modification_date: '2026-05-13'
author: Teoderick Contreras, Splunk
status: production
type: Anomaly
description: |
    The following analytic detects the execution of iexplore.exe (Internet Explorer) with the -extoff command-line flag, which disables all browser extensions. This flag is commonly abused by adversaries to launch a clean browser session that bypasses security controls such as antivirus browser extensions, toolbars, or group policy-enforced add-ons.
    Malicious documents or scripts may leverage iexplore.exe -extoff to open phishing pages, command-and-control interfaces, or download additional payloads in an environment free from security monitoring plugins. While this flag may be used legitimately by IT administrators for troubleshooting purposes, its use in modern enterprise environments is rare and should be considered suspicious—particularly when launched by Office applications, scripting engines (e.g., PowerShell, WScript), or scheduled tasks.
data_source:
    - Sysmon EventID 1
    - Windows Event Log Security 4688
    - CrowdStrike ProcessRollup2
search: |
    | tstats `security_content_summariesonly` min(_time) as firstTime max(_time)
    as lastTime from datamodel=Endpoint.Processes where
    (Processes.process_name = "iexplore.exe" OR Processes.original_file_name="IEXPLORE.EXE")
    Processes.process = "*-extoff*"
    by Processes.action Processes.dest Processes.original_file_name Processes.parent_process
    Processes.parent_process_exec Processes.parent_process_guid Processes.parent_process_id
    Processes.parent_process_name Processes.parent_process_path Processes.process Processes.process_exec
    Processes.process_guid Processes.process_hash Processes.process_id Processes.process_integrity_level
    Processes.process_name Processes.process_path Processes.user Processes.user_id Processes.vendor_product
    | `drop_dm_object_name(Processes)`
    | `security_content_ctime(firstTime)`
    | `security_content_ctime(lastTime)`
    | `windows_disable_internet_explorer_addons_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 `Processes` 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: Administrators may enable or disable this feature that may cause some false positive.
references:
    - https://www.hybrid-analysis.com/sample/e285feeca968b3ca22017a64363eea5e69ccd519696671df523291b089597875/588175f1aac2edf92bbed32f
drilldown_searches:
    - name: View the detection results for - "$user$" and "$dest$"
      search: '%original_detection_search% | search  user = "$user$" dest = "$dest$"'
      earliest_offset: $info_min_time$
      latest_offset: $info_max_time$
    - name: View risk events for the last 7 days for - "$user$" and "$dest$"
      search: '| from datamodel Risk.All_Risk | search normalized_risk_object IN ("$user$", "$dest$") | 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"
intermediate_findings:
    entities:
        - field: dest
          type: system
          score: 20
          message: An iexplore.exe process with the -extoff flag was launched on $dest$ by user $user$.
threat_objects:
    - field: parent_process_name
      type: parent_process_name
analytic_story:
    - Malicious Inno Setup Loader
asset_type: Endpoint
mitre_attack_id:
    - T1176.001
product:
    - Splunk Enterprise
    - Splunk Enterprise Security
    - Splunk Cloud
category: endpoint
security_domain: endpoint
tests:
    - name: True Positive Test
      attack_data:
        - data: https://media.githubusercontent.com/media/splunk/attack_data/master/datasets/attack_techniques/T1176.001/disable_extension/iexplore-extoff.log
          source: XmlWinEventLog:Microsoft-Windows-Sysmon/Operational
          sourcetype: XmlWinEventLog
      test_type: unit

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