splunk-security_content/docs/_posts/2021-10-18-disable_defender_blockatfirstseen_feature.md

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title	excerpt	categories	last_modified_at	toc	toc_label	tags
Disable Defender BlockAtFirstSeen Feature	Disable or Modify Tools, Impair Defenses	Endpoint	2021-10-18	true		Disable or Modify Tools Defense Evasion Impair Defenses Defense Evasion Splunk Enterprise Splunk Enterprise Security Splunk Cloud Endpoint

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Description

This analytic is to detect a suspicious modification of registry to disable windows defender feature. This technique is to bypassed or evade detection from Windows Defender AV product specially the BlockAtFirstSeen feature where it block suspicious file first seen in the host.

• Type: TTP
• Product: Splunk Enterprise, Splunk Enterprise Security, Splunk Cloud
• Datamodel: Endpoint
• Last Updated: 2021-10-18
• Author: Teoderick Contreras
• ID: 2dd719ac-3021-11ec-97b4-acde48001122

ATT&CK

ID	Technique	Tactic
T1562.001	Disable or Modify Tools	Defense Evasion

| T1562 | Impair Defenses | Defense Evasion |

Search

| tstats `security_content_summariesonly` count min(_time) as firstTime max(_time) as lastTime from datamodel=Endpoint.Registry where Registry.registry_path = "*\\Microsoft\\Windows Defender\\SpyNet*" Registry.registry_value_name = DisableBlockAtFirstSeen Registry.registry_value_data = 0x00000001 by Registry.dest Registry.user Registry.registry_path Registry.registry_value_name Registry.registry_value_data 
| `drop_dm_object_name(Registry)` 
| `security_content_ctime(lastTime)` 
| `security_content_ctime(firstTime)` 
| `disable_defender_blockatfirstseen_feature_filter`

Associated Analytic Story

• IceID

How To Implement

To successfully implement this search, you need to be ingesting logs with the registry value name, registry path, and registry value data from your endpoints. If you are using Sysmon, you must have at least version 6.0.4 of the Sysmon TA.

Required field

• _time
• Registry.dest
• Registry.user
• Registry.registry_value_name
• Registry.registry_key_name
• Registry.registry_path
• Registry.registry_value_data

Kill Chain Phase

• Exploitation

Known False Positives

admin or user may choose to disable windows defender product

RBA

Risk Score	Impact	Confidence	Message
49.0	70	70	modified/added/deleted registry entry registry_path in dest

Reference

• https://thedfirreport.com/2021/10/18/icedid-to-xinglocker-ransomware-in-24-hours/

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

• https://media.githubusercontent.com/media/splunk/attack_data/master/datasets/malware/icedid/disable_av/sysmon.log

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