Detection: Windows Disable Internet Explorer Addons

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.

Search

 1
 2| tstats `security_content_summariesonly` min(_time) as firstTime max(_time)
 3as lastTime from datamodel=Endpoint.Processes where 
 4(Processes.process_name = "iexplore.exe" OR Processes.original_file_name="IEXPLORE.EXE")
 5Processes.process = "*-extoff*" 
 6by Processes.action Processes.dest Processes.original_file_name Processes.parent_process
 7Processes.parent_process_exec Processes.parent_process_guid Processes.parent_process_id
 8Processes.parent_process_name Processes.parent_process_path Processes.process Processes.process_exec
 9Processes.process_guid Processes.process_hash Processes.process_id Processes.process_integrity_level
10Processes.process_name Processes.process_path Processes.user Processes.user_id Processes.vendor_product
11
12| `drop_dm_object_name(Processes)` 
13
14| `security_content_ctime(firstTime)` 
15
16| `security_content_ctime(lastTime)` 
17
18| `windows_disable_internet_explorer_addons_filter`

Data Source

Name	Platform	Sourcetype	Source
CrowdStrike ProcessRollup2	N/A	'crowdstrike:events:sensor'	'crowdstrike'
Sysmon EventID 1	Windows	'xmlwineventlog'	'XmlWinEventLog:Microsoft-Windows-Sysmon/Operational'
Windows Event Log Security 4688	Windows	'xmlwineventlog'	'XmlWinEventLog:Security'

Macros Used

Annotations

Default Configuration

This detection is configured by default in Splunk Enterprise Security to run with the following settings:

Implementation

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.

Associated Analytic Story

• Malicious Inno Setup Loader

Risk Based Analytics (RBA)

Risk Message:

An iexplore.exe process with the -extoff flag was launched on $dest$ by user $user$.

References

• https://www.hybrid-analysis.com/sample/e285feeca968b3ca22017a64363eea5e69ccd519696671df523291b089597875/588175f1aac2edf92bbed32f

Detection Testing

Replay any dataset to Splunk Enterprise by using our replay.py tool or the UI. Alternatively you can replay a dataset into a Splunk Attack Range

Source: GitHub | Version: 1