Access to a Sensitive LDAP Attribute

Identify access to sensitive Active Directory object attributes that contains credentials and decryption keys such as unixUserPassword, ms-PKI-AccountCredentials and msPKI-CredentialRoamingTokens.

Rule type: eql

Rule indices:

winlogbeat-*
logs-system.*
logs-windows.*

Severity: medium

Risk score: 47

Runs every: 5m

Searches indices from: now-9m (Date Math format, see also Additional look-back time)

Maximum alerts per execution: 100

References:

Tags:

Domain: Endpoint
OS: Windows
Use Case: Threat Detection
Tactic: Credential Access
Tactic: Privilege Escalation
Use Case: Active Directory Monitoring
Data Source: Active Directory
Data Source: System

Version: 12

Rule authors:

Elastic

Rule license: Elastic License v2

Setup

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Setup

The Audit Directory Service Access logging policy must be configured for (Success, Failure). Steps to implement the logging policy with Advanced Audit Configuration:

Computer Configuration >
Policies >
Windows Settings >
Security Settings >
Advanced Audit Policies Configuration >
Audit Policies >
DS Access >
Audit Directory Service Access (Success,Failure)

Rule query

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any where event.action in ("Directory Service Access", "object-operation-performed") and event.code == "4662" and

  not winlog.event_data.SubjectUserSid : "S-1-5-18" and

  winlog.event_data.Properties : (
   /* unixUserPassword */
  "*612cb747-c0e8-4f92-9221-fdd5f15b550d*",

  /* ms-PKI-AccountCredentials */
  "*b8dfa744-31dc-4ef1-ac7c-84baf7ef9da7*",

  /*  ms-PKI-DPAPIMasterKeys */
  "*b3f93023-9239-4f7c-b99c-6745d87adbc2*",

  /* msPKI-CredentialRoamingTokens */
  "*b7ff5a38-0818-42b0-8110-d3d154c97f24*"
  ) and

  /*
   Excluding noisy AccessMasks
   0x0 undefined and 0x100 Control Access
   https://learn.microsoft.com/en-us/windows/security/threat-protection/auditing/event-4662
   */
  not winlog.event_data.AccessMask in ("0x0", "0x100")

Framework: MITRE ATT&CK^TM

Tactic:
- Name: Credential Access
- ID: TA0006
- Reference URL: https://attack.mitre.org/tactics/TA0006/
Technique:
- Name: OS Credential Dumping
- ID: T1003
- Reference URL: https://attack.mitre.org/techniques/T1003/
Technique:
- Name: Unsecured Credentials
- ID: T1552
- Reference URL: https://attack.mitre.org/techniques/T1552/
Sub-technique:
- Name: Private Keys
- ID: T1552.004
- Reference URL: https://attack.mitre.org/techniques/T1552/004/
Tactic:
- Name: Privilege Escalation
- ID: TA0004
- Reference URL: https://attack.mitre.org/tactics/TA0004/
Technique:
- Name: Valid Accounts
- ID: T1078
- Reference URL: https://attack.mitre.org/techniques/T1078/
Sub-technique:
- Name: Domain Accounts
- ID: T1078.002
- Reference URL: https://attack.mitre.org/techniques/T1078/002/

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