What if I told you that there are new techniques being employed by cyber attackers that could allow them to move laterally within Active Directory environments, bypass authentication, and exfiltrate sensitive data? As new attack methods continue to evolve, it’s essential for you to stay updated on emerging threats and how they can affect your organization.
This image is property of lh7-rt.googleusercontent.com.
Understanding Active Directory Lateral Movement
Active Directory (AD) is a crucial component in many organizations, managing users, computers, and other devices on a network. Unfortunately, this interconnected structure presents an appealing target for attackers. By gaining initial access to one part of the network, they can leverage various techniques to move laterally, seeking higher privileges and access to sensitive data.
What Does Lateral Movement Mean?
Lateral movement refers to the techniques that attackers use to navigate through a network after breaching the initial layer of security. Rather than attacking the network perimeter directly, they look for vulnerabilities within the internal network, exploiting weaknesses in user accounts and systems to escalate privileges and retrieve valuable information.
In the context of Active Directory, lateral movement is particularly concerning. Attackers may exploit misconfigurations or flaws in the directory services to gain access without triggering typical security alerts.
New Active Directory Techniques for Bypassing Authentication
Recent findings have highlighted sophisticated techniques that exploit both hybrid Active Directory and Microsoft Entra ID environments. Understanding these new attack vectors is crucial for protecting your organization against unauthorized access.
Injecting Keys into OnPremAuthenticationFlowPolicy
One technique involves injecting keys into the OnPremAuthenticationFlowPolicy. This allows threat actors to forge Kerberos tickets, circumventing multi-factor authentication measures unnoticed. Here’s how it works:
-
Inject Custom Symmetric Keys: Attackers add backdoor keys to the
KeysInformationarray, enabling the generation of RC4-encrypted Kerberos tickets for any domain user within the network. - Persistence: Once these keys are in place, attackers can create persistent access mechanisms that enable them to authenticate without alerting security teams.
The ability to forge Kerberos tickets undetected creates significant vulnerabilities, especially as these modifications often leave no traces in Microsoft’s audit logs.
Abuse of Exchange Hybrid Certificates
Exchange hybrid deployments present another critical vector for lateral movement. Attackers can misuse certificate-based authentication to gain unauthorized access. Here’s how this occurs:
-
Extracting Certificates: By utilizing tools such as
ADSyncCertDump.exe, attackers can extract Exchange hybrid certificates from on-premises servers. - Service-to-Service Tokens: These certificates allow the attackers to request Service-to-Service (S2S) tokens from Microsoft’s Access Control Service (ACS). The tokens grant unrestricted access to Exchange Online and SharePoint, without the need for user context validation.
- Duration of Access: The tokens provide access for 24-hour periods, and once issued, they leave no audit logs, making detection extremely challenging.
Consequences of Impersonation
The implications of successfully executing these techniques are severe. Attackers can impersonate any user within the tenant, effectively gaining access to sensitive systems and data across the entire organization. The successful execution of these attacks not only compromises sensitive information but also poses a threat to overall organizational integrity.
Mitigation Strategies
With the rising threat of these new lateral movement techniques, implementing robust mitigation strategies is essential. Microsoft is aware of these vulnerabilities and has begun implementing mitigations. Here’s what you can do on your end:
Perform Immediate Audits
Start by auditing your Exchange hybrid configurations. Use detection queries such as:
AuditLogs | where InitiatedBy.user.displayName == “Office 365 Exchange Online”
This can help identify any suspicious activities or unauthorized modifications.
Enable Hard Matching in Entra ID Connect
By enabling hard matching in Entra ID Connect, you can help prevent cloud-only account takeovers. This step ensures that user identities are correctly verified and prevents unauthorized access attempts.
Implement the Principle of Least Privilege
Adopt the principle of least privilege for Directory Synchronization Accounts. By restricting access to only those that require it to perform their job functions, you minimize potential attack vectors.
Monitor for Unauthorized Modifications
Be proactive in monitoring for unauthorized changes to authentication policies. The quicker you can identify these modifications, the better your chances of mitigating any potential breaches.
Transition to Dedicated Exchange Hybrid Applications
Consider transitioning to dedicated Exchange hybrid applications. This step can help limit your organization’s exposure to attacks targeting certificate-based authentication.
Final Thoughts
In conclusion, as cyber threats evolve, your defenses must also adapt. Understanding these new Active Directory lateral movement techniques is a vital step in bolstering your organization’s cybersecurity posture. Awareness is your first line of defense, and implementing the strategies discussed can significantly reduce your risk of an attack.
Stay informed, stay prepared, and consider this a crucial aspect of your security strategy. By taking proactive steps now, you can protect your organization from future threats that seek to exploit vulnerabilities in Active Directory and associated systems.
If you have any specific questions or concerns about your organization’s security practices, exploring resources from cybersecurity professionals or industry experts can provide additional insights that are tailored to your unique environment. Keep your systems updated, and always be on the lookout for new threats in this ever-evolving digital landscape.