Disabling User Account Control via Registry Modification

Elastic Stack Serverless Security

User Account Control (UAC) can help mitigate the impact of malware on Windows hosts. With UAC, apps and tasks always run in the security context of a non-administrator account, unless an administrator specifically authorizes administrator-level access to the system. This rule identifies registry value changes to bypass User Access Control (UAC) protection.

Rule type: eql

Rule indices:

• winlogbeat-*
• logs-endpoint.events.*
• logs-windows.*

Severity: medium

Risk score: 47

Runs every: 5m

Searches indices from: now-9m (https://www.elastic.co/guide/en/elasticsearch/reference/current/common-options.html#date-math[Date Math format], see also Additional look-back time)

Maximum alerts per execution: 100

References:

• https://www.greyhathacker.net/?p=796
• https://docs.microsoft.com/en-us/windows/security/identity-protection/user-account-control/user-account-control-group-policy-and-registry-key-settings
• https://docs.microsoft.com/en-us/windows/security/identity-protection/user-account-control/user-account-control-overview

Tags:

• Elastic
• Host
• Windows
• Threat Detection
• Privilege Escalation

Version: 4

Rule authors:

• Elastic

Rule license: Elastic License v2

If enabling an EQL rule on a non-elastic-agent index (such as beats) for versions <8.2, events will not define event.ingested and default fallback for EQL rules was not added until 8.2, so you will need to add a custom pipeline to populate event.ingested to @timestamp for this rule to work.

registry where event.type == "change" and
  registry.path :
    (
      "HKLM\\SOFTWARE\\Microsoft\\Windows\\CurrentVersion\\Policies\\System\\EnableLUA",
      "HKLM\\SOFTWARE\\Microsoft\\Windows\\CurrentVersion\\Policies\\System\\ConsentPromptBehaviorAdmin",
      "HKLM\\SOFTWARE\\Microsoft\\Windows\\CurrentVersion\\Policies\\System\\PromptOnSecureDesktop"
    ) and
  registry.data.strings : ("0", "0x00000000")

Framework: MITRE ATT&CKTM

• Tactic:

  • Name: Privilege Escalation
  • ID: TA0004
  • Reference URL: https://attack.mitre.org/tactics/TA0004/

• Technique:

  • Name: Abuse Elevation Control Mechanism
  • ID: T1548
  • Reference URL: https://attack.mitre.org/techniques/T1548/

• Sub-technique:

  • Name: Bypass User Account Control
  • ID: T1548.002
  • Reference URL: https://attack.mitre.org/techniques/T1548/002/

• Tactic:

  • Name: Defense Evasion
  • ID: TA0005
  • Reference URL: https://attack.mitre.org/tactics/TA0005/

• Technique:

  • Name: Abuse Elevation Control Mechanism
  • ID: T1548
  • Reference URL: https://attack.mitre.org/techniques/T1548/

• Sub-technique:

  • Name: Bypass User Account Control
  • ID: T1548.002
  • Reference URL: https://attack.mitre.org/techniques/T1548/002/