Disable Defender BlockAtFirstSeen Feature
The following analytic detects the modification of the Windows registry to disable the Windows Defender BlockAtFirstSeen feature. It leverages data from the Endpoint.Registry data model, specifically monitoring…
Description
The following analytic detects the modification of the Windows registry to disable the Windows Defender BlockAtFirstSeen feature. It leverages data from the Endpoint.Registry data model, specifically monitoring changes to the registry path associated with Windows Defender SpyNet and the DisableBlockAtFirstSeen value. This activity is significant because disabling this feature can allow malicious files to bypass initial detection by Windows Defender, increasing the risk of malware infection. If confirmed malicious, this action could enable attackers to execute malicious code undetected, leading to potential system compromise and data breaches.
Detection logic
Detection requirements
- Platform
- ContainersESXiIaaSLinuxmacOSNetwork DevicesWindows
The rule states no platform. This is derived from the ATT&CK technique it maps to.
- Log source category
- sysmon_eventid_13
Known benign triggers
- admin or user may choose to disable windows defender product
MITRE ATT&CK mappings
0 exclusive techniques.This is coverage no other published rule has; it is not this rule's total technique count.
References
| Reference | Cited by |
|---|---|
| thedfirreport.com/2021/10/18/icedid-to-xinglocker-ransomware-in-24-hours/ | 25from 3 sources |
From the source
- At source
- Open at source
- Upstream identifier
- 2dd719ac-3021-11ec-97b4-acde48001122
- Tagged by the source as
- AzorultCISA AA23-347AIcedIDSolarWinds WHD RCE Post ExploitationWindows Registry AbuseEndpointendpointSplunk CloudSplunk EnterpriseSplunk Enterprise Securityendpoint
Licence
- Published under
- Apache License 2.0Read the licence
- Attribution
- Required
- Obtained under
- Apache-2.0Read the origin licence
Authorship
- Written by
- Published
- Aug 26, 2026
- Version
- 1