In today’s complex cybersecurity landscape, understanding domain persistence techniques is crucial for both offensive security professionals and defenders. This comprehensive guide explores advanced methods attackers use to maintain access to compromised domains and how security teams can detect and prevent these techniques.

Understanding Domain Persistence

Domain persistence refers to the methods and techniques used to maintain long-term access to a compromised network environment after initial exploitation. In enterprise environments, these techniques often focus on Active Directory infrastructure, as it serves as the backbone of most corporate networks.

The Importance of Understanding Persistence Mechanisms

Security professionals need to understand persistence mechanisms for two primary reasons:

  • Defensive teams must know what to look for when hunting threats
  • Red teams need to understand these techniques for realistic security assessments

Common Domain Persistence Techniques

Golden Ticket Attack

The Golden Ticket attack is one of the most powerful persistence techniques in Active Directory environments. It involves compromising the KRBTGT account, which is used to encrypt all Kerberos tickets within a domain.

To create a Golden Ticket:

  mimikatz # kerberos::golden /domain:contoso.local /sid:S-1-5-21-1234567890-1234567890-1234567890 /krbtgt:hash /user:admin /ptt

This creates a ticket that grants persistent domain admin access, often remaining valid even after password changes.

Silver Ticket Attack

Similar to Golden Tickets, Silver Tickets are forged service tickets that provide access to specific services. They’re more subtle than Golden Tickets as they target individual services rather than domain-wide access.

Example implementation:

  mimikatz # kerberos::golden /domain:contoso.local /sid:S-1-5-21-1234567890-1234567890-1234567890 /target:server.contoso.local /service:CIFS /rc4:hash /user:admin /ptt

Domain Controller Synchronization

Attackers often exploit Active Directory replication mechanisms to maintain persistence. By implementing a rogue domain controller, they can:

  • Capture authentication attempts
  • Modify directory objects
  • Maintain access even after credential changes

Security Descriptor Modification

This technique involves modifying Access Control Lists (ACLs) on critical objects to maintain privileged access:

  Add-ObjectAcl -TargetDistinguishedName "DC=contoso,DC=local" -PrincipalSamAccountName "compromised_user" -Rights DCSync

Advanced Persistence Mechanisms

Shadow Credentials

Shadow credentials leverage certificate-based authentication to maintain persistence. This technique involves:

  • Creating a new certificate
  • Adding it to the msDS-KeyCredentialLink attribute
  • Using the certificate for authentication

Implementation example:

  Whisker.exe add /target:username /domain:contoso.local /dc:dc01.contoso.local /path:cert.pfx

DCShadow

DCShadow is a sophisticated technique that temporarily registers a computer as a domain controller to push malicious changes:

  lsadump::dcshadow /object:target_account /attribute:userAccountControl /value:...

Detection and Prevention Strategies

Monitoring Critical Changes

Implement robust monitoring for:

  • Changes to privileged groups
  • Modifications to security descriptors
  • New service principal names
  • Certificate registration events

Event Log Monitoring

Key Windows Event IDs to monitor:

  • 4662 (Directory Service Access)
  • 4742 (Computer Account Changes)
  • 5136 (Directory Service Changes)

Advanced Detection Methods

Implement advanced detection mechanisms:

  # PowerShell script to detect suspicious ACL changes
Get-ADObject -Filter * -Properties nTSecurityDescriptor | Where-Object {$_.nTSecurityDescriptor.Access.IdentityReference -match "suspicious_user"}

Mitigation Strategies

Privileged Access Management

  • Implement time-based privileged access
  • Use Protected Users group for sensitive accounts
  • Enable Privileged Access Workstations (PAW)

Technical Controls

Implement these critical controls:

  # Enable Advanced Audit Policy
auditpol /set /subcategory:"Directory Service Changes" /success:enable /failure:enable

# Configure KRBTGT password rotation
New-ScheduledTaskAction -Execute 'PowerShell.exe' -Argument '-File C:\Scripts\Rotate-KRBTGTPassword.ps1'

Best Practices for Domain Security

Regular Maintenance

  • Rotate KRBTGT password regularly
  • Monitor and clean up stale objects
  • Implement least privilege access

Advanced Hardening 

  # Enable LDAP signing and channel binding
Set-ItemProperty -Path HKLM:\System\CurrentControlSet\Services\NTDS\Parameters -Name "LdapEnforceChannelBinding" -Value 2

Conclusion

Understanding domain persistence techniques is crucial for both attackers and defenders. By implementing proper monitoring, detection, and prevention strategies, organizations can better protect their Active Directory environments from sophisticated persistence attacks.

Remember that security is an ongoing process, and staying updated with the latest persistence techniques and countermeasures is essential for maintaining a robust security posture.

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Last updated 03 Nov 2024, 18:05 +0530 . history