Disabling User Account Control via Registry Modification

  1[metadata]
  2creation_date = "2021/01/20"
  3integration = ["endpoint", "windows", "m365_defender", "sentinel_one_cloud_funnel", "crowdstrike"]
  4maturity = "production"
  5updated_date = "2026/09/18"
  6
  7[rule]
  8author = ["Elastic"]
  9description = """
 10User Account Control (UAC) can help mitigate the impact of malware on Windows hosts. With UAC, apps and tasks always run
 11in the security context of a non-administrator account, unless an administrator specifically authorizes
 12administrator-level access to the system. This rule identifies registry value changes to bypass User Access Control
 13(UAC) protection.
 14"""
 15from = "now-9m"
 16index = [
 17    "winlogbeat-*",
 18    "logs-endpoint.events.registry-*",
 19    "logs-windows.sysmon_operational-*",
 20    "endgame-*",
 21    "logs-m365_defender.event-*",
 22    "logs-sentinel_one_cloud_funnel.*",
 23    "logs-crowdstrike.fdr*",
 24]
 25language = "eql"
 26license = "Elastic License v2"
 27name = "Disabling User Account Control via Registry Modification"
 28note = """## Triage and analysis
 29
 30### Investigating Disabling User Account Control via Registry Modification
 31
 32Windows User Account Control (UAC) allows a program to elevate its privileges (tracked as low to high integrity levels) to perform a task under administrator-level permissions, possibly by prompting the user for confirmation. UAC can deny an operation under high-integrity enforcement, or allow the user to perform the action if they are in the local administrators group and enter an administrator password when prompted.
 33
 34For more information about the UAC and how it works, check the [official Microsoft docs page](https://docs.microsoft.com/en-us/windows/security/identity-protection/user-account-control/how-user-account-control-works).
 35
 36Attackers may disable UAC to execute code directly in high integrity. This rule identifies registry value changes to bypass the UAC protection.
 37
 38#### Possible investigation steps
 39
 40- Investigate the process execution chain (parent process tree) for unknown processes. Examine their executable files for prevalence, whether they are located in expected locations, and if they are signed with valid digital signatures.
 41- Investigate other alerts associated with the user/host during the past 48 hours.
 42- Inspect the host for suspicious or abnormal behaviors in the alert timeframe.
 43- Investigate abnormal behaviors observed by the subject process such as network connections, registry or file modifications, and any spawned child processes.
 44- Analyze non-system processes executed with high integrity after UAC was disabled for unknown or suspicious processes.
 45- Retrieve the suspicious processes' executables and determine if they are malicious:
 46  - Use a private sandboxed malware analysis system to perform analysis.
 47    - Observe and collect information about the following activities:
 48      - Attempts to contact external domains and addresses.
 49      - File and registry access, modification, and creation activities.
 50      - Service creation and launch activities.
 51      - Scheduled tasks creation.
 52  - Use the PowerShell `Get-FileHash` cmdlet to get the files' SHA-256 hash values.
 53    - Search for the existence and reputation of the hashes in resources like VirusTotal, Hybrid-Analysis, CISCO Talos, Any.run, etc.
 54
 55### False positive analysis
 56
 57- This activity is unlikely to happen legitimately. Benign true positives (B-TPs) can be added as exceptions if necessary.
 58
 59### Response and remediation
 60
 61- Initiate the incident response process based on the outcome of the triage.
 62- Isolate the involved host to prevent further post-compromise behavior.
 63- If the triage identified malware, search the environment for additional compromised hosts.
 64  - Implement temporary network rules, procedures, and segmentation to contain the malware.
 65  - Stop suspicious processes.
 66  - Immediately block the identified indicators of compromise (IoCs).
 67  - Inspect the affected systems for additional malware backdoors like reverse shells, reverse proxies, or droppers that attackers could use to reinfect the system.
 68- Remove and block malicious artifacts identified during triage.
 69- Restore UAC settings to the desired state.
 70- Run a full antimalware scan. This may reveal additional artifacts left in the system, persistence mechanisms, and malware components.
 71- Investigate credential exposure on systems compromised or used by the attacker to ensure all compromised accounts are identified. Reset passwords for these accounts and other potentially compromised credentials, such as email, business systems, and web services.
 72- Determine the initial vector abused by the attacker and take action to prevent reinfection through the same vector.
 73- Using the incident response data, update logging and audit policies to improve the mean time to detect (MTTD) and the mean time to respond (MTTR).
 74"""
 75
 76setup = """## Setup
 77
 78This rule is designed for data generated by [Elastic Defend](https://www.elastic.co/security/endpoint-security), which provides native endpoint detection and response, along with event enrichments designed to work with our detection rules.
 79
 80Setup instructions: https://ela.st/install-elastic-defend
 81
 82### Additional data sources
 83
 84This rule also supports the following third-party data sources. For setup instructions, refer to the links below:
 85
 86- [CrowdStrike](https://ela.st/crowdstrike-integration)
 87- [Microsoft Defender XDR](https://ela.st/m365-defender)
 88- [SentinelOne Cloud Funnel](https://ela.st/sentinel-one-cloud-funnel)
 89- [Sysmon Registry Events](https://ela.st/sysmon-event-reg-setup)
 90"""
 91
 92references = [
 93    "https://www.greyhathacker.net/?p=796",
 94    "https://docs.microsoft.com/en-us/windows/security/identity-protection/user-account-control/user-account-control-group-policy-and-registry-key-settings",
 95    "https://docs.microsoft.com/en-us/windows/security/identity-protection/user-account-control/user-account-control-overview",
 96    "https://www.elastic.co/security-labs/dissecting-remcos-rat-part-four",
 97]
 98risk_score = 47
 99rule_id = "d31f183a-e5b1-451b-8534-ba62bca0b404"
100severity = "medium"
101tags = [
102    "Domain: Endpoint",
103    "OS: Windows",
104    "Use Case: Threat Detection",
105    "Tactic: Privilege Escalation",
106    "Resources: Investigation Guide",
107    "Data Source: Elastic Endgame",
108    "Data Source: Elastic Defend",
109    "Data Source: Sysmon",
110    "Data Source: Microsoft Defender XDR",
111    "Data Source: SentinelOne",
112    "Data Source: Crowdstrike",
113    "Noise: High",
114    "Performance: Normal",
115    "Profile: Aggressive",
116    "Rule Type: Event Correlation (EQL)",
117    "Platform: Windows",
118]
119timestamp_override = "event.ingested"
120type = "eql"
121
122query = '''
123registry where host.os.type == "windows" and event.type == "change" and
124  registry.value : ("EnableLUA", "ConsentPromptBehaviorAdmin", "PromptOnSecureDesktop") and
125  registry.data.strings : ("0", "0x00000000")
126
127  /*
128    Full registry key path omitted due to data source variations:
129    HKLM\\SOFTWARE\\Microsoft\\Windows\\CurrentVersion\\Policies\\System\\EnableLUA
130    HKLM\\SOFTWARE\\Microsoft\\Windows\\CurrentVersion\\Policies\\System\\ConsentPromptBehaviorAdmin
131    HKLM\\SOFTWARE\\Microsoft\\Windows\\CurrentVersion\\Policies\\System\\PromptOnSecureDesktop
132  */
133'''
134
135
136[[rule.threat]]
137framework = "MITRE ATT&CK"
138
139[[rule.threat.technique]]
140id = "T1548"
141name = "Abuse Elevation Control Mechanism"
142reference = "https://attack.mitre.org/techniques/T1548/"
143
144[[rule.threat.technique.subtechnique]]
145id = "T1548.002"
146name = "Bypass User Account Control"
147reference = "https://attack.mitre.org/techniques/T1548/002/"
148
149[rule.threat.tactic]
150id = "TA0004"
151name = "Privilege Escalation"
152reference = "https://attack.mitre.org/tactics/TA0004/"
153
154[[rule.threat]]
155framework = "MITRE ATT&CK"
156
157[[rule.threat.technique]]
158id = "T1112"
159name = "Modify Registry"
160reference = "https://attack.mitre.org/techniques/T1112/"
161
162[[rule.threat.technique]]
163id = "T1562"
164name = "Impair Defenses"
165reference = "https://attack.mitre.org/techniques/T1562/"
166
167[[rule.threat.technique.subtechnique]]
168id = "T1562.001"
169name = "Disable or Modify Tools"
170reference = "https://attack.mitre.org/techniques/T1562/001/"
171
172[rule.threat.tactic]
173id = "TA0005"
174name = "Defense Evasion"
175reference = "https://attack.mitre.org/tactics/TA0005/"