Detection: Disabling Remote User Account Control

Updated Date: 2024-05-18 ID: bbc644bc-37df-4e1a-9c88-ec9a53e2038c Author: David Dorsey, Patrick Bareiss, Splunk Type: TTP Product: Splunk Enterprise Security

Description

The following analytic identifies modifications to the registry key that controls the enforcement of Windows User Account Control (UAC). It detects changes to the registry path HKLM\SOFTWARE\Microsoft\Windows\CurrentVersion\Policies\System\EnableLUA where the value is set to 0x00000000. This activity is significant because disabling UAC can allow unauthorized changes to the system without user consent, potentially leading to privilege escalation. If confirmed malicious, an attacker could gain elevated privileges, making it easier to execute further attacks or maintain 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=*HKLM\\SOFTWARE\\Microsoft\\Windows\\CurrentVersion\\Policies\\System\\EnableLUA* Registry.registry_value_data="0x00000000" by Registry.dest, Registry.registry_key_name Registry.user Registry.registry_path Registry.registry_value_data Registry.action 
3| `drop_dm_object_name(Registry)` 
4| `disabling_remote_user_account_control_filter`

Data Source

Name	Platform	Sourcetype	Source	Supported App
Sysmon EventID 12	Windows	`'xmlwineventlog'`	`'XmlWinEventLog:Microsoft-Windows-Sysmon/Operational'`	N/A

Macros Used

Name	Value
security_content_summariesonly	`summariesonly=`summariesonly_config `allow_old_summaries=`oldsummaries_config `fillnull_value=`fillnull_config``
disabling_remote_user_account_control_filter	`search *`

disabling_remote_user_account_control_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 must be ingesting data that records registry activity from your hosts to populate the endpoint data model in the registry node. This is typically populated via endpoint detection-and-response product, such as Carbon Black, or via other endpoint data sources, such as Sysmon. The data used for this search is typically generated via logs that report registry modifications.

Known False Positives

This registry key may be modified via administrators to implement a change in system policy. This type of change should be a very rare occurrence.

Associated Analytic Story

Risk Based Analytics (RBA)

Risk Message	Risk Score	Impact	Confidence
The Windows registry keys that control the enforcement of Windows User Account Control (UAC) were modified on $dest$ by $user$.	42	70	60

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

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: 5