Detection: Windows Impair Defense Deny Security Software With Applocker

Description

The following analytic detects modifications in the Windows registry by the Applocker utility that deny the execution of various security products. This detection leverages data from the Endpoint.Registry datamodel, focusing on specific registry paths and values indicating a "Deny" action against known antivirus and security software. This activity is significant as it may indicate an attempt to disable security defenses, a tactic observed in malware like Azorult. If confirmed malicious, this could allow attackers to bypass security measures, facilitating further malicious activities and persistence within the environment.

Search

1
2| tstats `security_content_summariesonly` count min(_time) as firstTime max(_time) as lastTime FROM datamodel=Endpoint.Registry where (Registry.registry_path= "*\\SOFTWARE\\Microsoft\\Windows\\CurrentVersion\\Group Policy Objects\\*" AND Registry.registry_path= "*}Machine\\Software\\Policies\\Microsoft\\Windows\\SrpV2*") OR Registry.registry_path="*\\Software\\Policies\\Microsoft\\Windows\\SrpV2*" AND Registry.registry_value_data = "*Action\=\"Deny\"*" AND Registry.registry_value_data IN("*O=SYMANTEC*","*O=MCAFEE*","*O=KASPERSKY*","*O=BLEEPING COMPUTER*", "*O=PANDA SECURITY*","*O=SYSTWEAK SOFTWARE*", "*O=TREND MICRO*", "*O=AVAST*", "*O=GRIDINSOFT*", "*O=MICROSOFT*", "*O=NANO SECURITY*", "*O=SUPERANTISPYWARE.COM*", "*O=DOCTOR WEB*", "*O=MALWAREBYTES*", "*O=ESET*", "*O=AVIRA*", "*O=WEBROOT*") by  Registry.user Registry.registry_path Registry.registry_value_data Registry.action Registry.registry_key_name Registry.dest 
3| `drop_dm_object_name(Registry)` 
4| `security_content_ctime(firstTime)` 
5| `security_content_ctime(lastTime)` 
6| `windows_impair_defense_deny_security_software_with_applocker_filter`

Data Source

Name	Platform	Sourcetype	Source
Sysmon EventID 12	Windows	'xmlwineventlog'	'XmlWinEventLog:Microsoft-Windows-Sysmon/Operational'
Sysmon EventID 13	Windows	'xmlwineventlog'	'XmlWinEventLog:Microsoft-Windows-Sysmon/Operational'

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 Registry node. Also make sure that this registry was included in your config files ex. sysmon config to be monitored.

Known False Positives

False positives may be present based on organization use of Applocker. Filter as needed.

Associated Analytic Story

• Azorult

Risk Based Analytics (RBA)

References

• https://app.any.run/tasks/a6f2ffe2-e6e2-4396-ae2e-04ea0143f2d8/

• https://www.microsoftpressstore.com/articles/article.aspx?p=2228450&seqNum=11

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: 3