Active Directory’s Discretionary Access Control Lists (DACLs) serve as fundamental security mechanisms governing object permissions within directory services. Among these permissions, GenericWrite presents particularly severe risks when misconfigured, enabling attackers to manipulate critical attributes and escalate privileges. This technical analysis explores the enterprise security implications of GenericWrite vulnerabilities, documented exploitation patterns, and Microsoft-recommended mitigation strategies.
Understanding DACL Security and GenericWrite Risks
Active Directory implements object security through DACLs containing Access Control Entries (ACEs) that define permissions for security principals. The GenericWrite permission (ADS_RIGHT_GENERIC_WRITE) grants modification rights to most non-protected attributes on target objects, including sensitive properties like group memberships and service principal names. Security teams should note that this permission becomes particularly dangerous when:
- Applied to privileged groups such as Domain Admins or Enterprise Admins
- Granted to standard user accounts through improper delegation
- Inherited via organizational unit structures without proper filtering
Microsoft’s Active Directory documentation emphasizes that GenericWrite combines multiple extended rights, making it functionally equivalent to having WriteProperty permissions on most attributes.
Documented Exploitation Patterns
Security researchers have identified several consistent attack patterns leveraging GenericWrite permissions. These techniques have been validated through controlled testing environments and documented in resources like The Hacker Recipes and BloodHound’s official documentation.
Group Membership Manipulation
When attackers obtain GenericWrite on security groups, they can add compromised accounts to privileged groups. This attack path frequently appears in BloodHound analyses showing the AddMember relationship. The 2023 Lares research on Active Directory ACL risks found this technique remains prevalent in real-world attacks.
Service Principal Name Manipulation
Attackers with GenericWrite on user objects can modify servicePrincipalName attributes to facilitate Kerberoasting attacks. This technique was demonstrated in the Abusing-rights-in-a-Domain GitHub repository, showing how SPN modifications enable credential theft against service accounts.
Enterprise Detection Strategies
Security operations teams should implement monitoring for these key indicators of GenericWrite exploitation:
| Event ID | Description | Attack Correlation |
|---|---|---|
| 4732 | Security group membership change | Group privilege escalation |
| 5136 | Directory service object modification | SPN manipulation |
| 4724 | Password reset attempt | Credential takeover |
Microsoft’s audit policy recommendations provide additional guidance on monitoring sensitive Active Directory operations.
Mitigation and Hardening Recommendations
Based on observed attack patterns and Microsoft security guidance, organizations should implement these protective measures:
- Delegation Review: Conduct quarterly audits of Active Directory DACLs using tools like ADACLScanner or BloodHound’s ACL analysis features
- Privileged Access: Restrict management of sensitive groups to Privileged Access Workstations (PAWs) with multi-factor authentication
- Monitoring: Implement SIEM alerts for unexpected group membership changes and SPN modifications
- Delegation Models: Adopt Microsoft’s OU-based delegation models rather than direct permission assignments
Conclusion
GenericWrite permissions represent a significant attack surface in Active Directory environments when improperly configured. Security teams should prioritize regular DACL audits, implement strict change controls for sensitive permissions, and maintain vigilant monitoring for exploitation patterns. As Active Directory environments continue to evolve, maintaining proper access controls remains critical for enterprise security postures.
References
- The Hacker Recipes: DACL abuse – Technical reference for Active Directory exploitation techniques
- Lares Research: Active Directory ACL risks – 2023 analysis of real-world DACL misconfigurations
- BloodHound Documentation: GenericWrite – Official guidance on permission analysis
- Microsoft Security Best Practices – Official audit policy recommendations
