Detection: Disable UAC Remote Restriction

Updated Date: 2024-11-14 ID: 9928b732-210e-11ec-b65e-acde48001122 Author: Teoderick Contreras, Splunk, Steven Dick Type: TTP Product: Splunk Enterprise Security

Description

The following analytic detects the modification of the registry to disable UAC remote restriction by setting the "LocalAccountTokenFilterPolicy" value to "0x00000001". It leverages data from the Endpoint.Registry data model, specifically monitoring changes to the registry path "\CurrentVersion\Policies\System". This activity is significant because disabling UAC remote restriction can allow an attacker to bypass User Account Control (UAC) protections, potentially leading to privilege escalation. If confirmed malicious, this could enable an attacker to execute unauthorized actions with elevated privileges, compromising the security of the affected system.

Search

1
2| tstats `security_content_summariesonly` count min(_time) as firstTime max(_time) as lastTime FROM datamodel=Endpoint.Registry WHERE (Registry.registry_path="*\\CurrentVersion\\Policies\\System*" Registry.registry_value_name="LocalAccountTokenFilterPolicy" Registry.registry_value_data="0x00000001"  ) BY Registry.user Registry.dest Registry.registry_path Registry.registry_key_name Registry.registry_value_name Registry.registry_value_data Registry.process_guid 
3| `drop_dm_object_name(Registry)`
4| where isnotnull(registry_value_data) 
5| `security_content_ctime(firstTime)` 
6| `security_content_ctime(lastTime)` 
7| `disable_uac_remote_restriction_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

Name	Value
security_content_ctime	`convert timeformat="%Y-%m-%dT%H:%M:%S" ctime($field$)`
disable_uac_remote_restriction_filter	`search *`

disable_uac_remote_restriction_filter is an empty macro by default. It allows the user to filter out any results (false positives) without editing the SPL.

Annotations

- MITRE ATT&CK

+ Kill Chain Phases

+ NIST

+ CIS

- Threat Actors

ID	Technique	Tactic
T1548.002	Bypass User Account Control	Defense Evasion
T1548	Abuse Elevation Control Mechanism	Privilege Escalation

KillChainPhase.EXPLOITAITON

NistCategory.DE_CM

Cis18Value.CIS_10

APT29

APT37

BRONZE BUTLER

Cobalt Group

Earth Lusca

Evilnum

MuddyWater

Patchwork

Threat Group-3390

Default Configuration

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

Setting	Value
Disabled	true
Cron Schedule	`0 * * * *`
Earliest Time	`-70m@m`
Latest Time	`-10m@m`
Schedule Window	`auto`
Creates Notable	Yes
Rule Title	`%name%`
Rule Description	`%description%`
Notable Event Fields	user, dest
Creates Risk Event	True

This configuration file applies to all detections of type TTP. These detections will use Risk Based Alerting and generate Notable Events.

Implementation

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 2.0 of the offical Sysmon TA. https://splunkbase.splunk.com/app/5709

Known False Positives

admin may set this policy for non-critical machine.

Associated Analytic Story

Risk Based Analytics (RBA)

Risk Message	Risk Score	Impact	Confidence
Modified/added/deleted registry entry $registry_path$ in $dest$	80	80	100

The Risk Score is calculated by the following formula: Risk Score = (Impact * Confidence/100). Initial Confidence and Impact is set by the analytic author.

References

https://docs.microsoft.com/en-us/troubleshoot/windows-server/windows-security/user-account-control-and-remote-restriction

Detection Testing

Test Type	Status	Dataset	Source	Sourcetype
Validation	✅ Passing	N/A	N/A	N/A
Unit	✅ Passing	Dataset	`XmlWinEventLog:Microsoft-Windows-Sysmon/Operational`	`XmlWinEventLog`
Integration	✅ Passing	Dataset	`XmlWinEventLog:Microsoft-Windows-Sysmon/Operational`	`XmlWinEventLog`

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: 7