Windows Impair Defense Disable Web Evaluation
Description
The following analytic detects modifications to the Windows registry entry "EnableWebContentEvaluation" to disable Windows Defender web content evaluation. It leverages data from the Endpoint.Registry datamodel, specifically monitoring changes where the registry value is set to "0x00000000". This activity is significant as it indicates an attempt to impair browser security features, potentially allowing malicious web content to bypass security checks. If confirmed malicious, this could lead to users interacting with harmful scripts or unsafe web elements, increasing the risk of system exploitation and security breaches.
- Type: TTP
- Product: Splunk Enterprise, Splunk Enterprise Security, Splunk Cloud
- Datamodel: Endpoint, Web
- Last Updated: 2024-05-27
- Author: Teoderick Contreras, Splunk
- ID: e234970c-dcf5-4f80-b6a9-3a562544ca5b
Annotations
ATT&CK
Kill Chain Phase
- Exploitation
NIST
- DE.CM
CIS20
- CIS 10
CVE
Search
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| tstats `security_content_summariesonly` count FROM datamodel=Endpoint.Registry WHERE Registry.registry_path= "*\\Windows\\CurrentVersion\\AppHost\\EnableWebContentEvaluation" Registry.registry_value_data= "0x00000000" BY _time span=1h Registry.dest Registry.user Registry.registry_path Registry.registry_key_name Registry.registry_value_name Registry.registry_value_data Registry.process_guid
| `drop_dm_object_name(Registry)`
| `security_content_ctime(firstTime)`
| `security_content_ctime(lastTime)`
| `windows_impair_defense_disable_web_evaluation_filter`
Macros
The SPL above uses the following Macros:
windows_impair_defense_disable_web_evaluation_filter is a empty macro by default. It allows the user to filter out any results (false positives) without editing the SPL.
Required fields
List of fields required to use this analytic.
- _time
- Registry.registry_key_name
- Registry.registry_value_name
- Registry.dest
- Registry.user
- Registry.registry_path
- Registry.action
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 Registry
node.
Known False Positives
It is unusual to turn this feature off a Windows system since it is a default security control, although it is not rare for some policies to disable it. Although no false positives have been identified, use the provided filter macro to tune the search.
Associated Analytic Story
RBA
Risk Score | Impact | Confidence | Message |
---|---|---|---|
49.0 | 70 | 70 | Windows Defender web content evaluation feature set to disable on $dest$. |
The Risk Score is calculated by the following formula: Risk Score = (Impact * Confidence/100). Initial Confidence and Impact is set by the analytic author.
Reference
- https://x.com/malmoeb/status/1742604217989415386?s=20
- https://github.com/undergroundwires/privacy.sexy
Test Dataset
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 | version: 2