Active Directory (AD) is crucial for an organization’s identity and access management strategy, but its complex architecture is also a prime zone for overlooked vulnerabilities. One such feature that’s often overlooked is Active Directory Certificate Services (ADCS).
Active Directory Certificate Services
ADCS is a service that provides a robust solution for managing digital certificates in a Windows Server environment. It leverages AD to manage certificates in a domain environment. Certificates can be used to secure several services in AD like encrypted email communication, VPN-based access, and more.
Certificates are virtual locks, but they can be broken by just using the right set of tools, without the need to be proficient with the underlying technology.
Extracting configuration information from ADCS
By using a Linux machine thats not joined to an AD domain and with a low-privileged users’ credentials, we were able to obtain the configuration details of ADCS.
As you can see from the screenshot above, the information was dumped into a text file. Let’s open it and see if we find anything useful.
From the illustrated screenshot, we can see that a vulnerability ESC8 was found. Attackers can exploit this vulnerability to authenticate as a domain controller, potentially gaining access to sensitive resources.
It’s important to understand that this vulnerability was found with minimal effort.
Below is another such example of a vulnerability caused due to a misconfiguration on an administrator certificate template in ADCS, potentially allowing a malicious insiders to issue unauthorized certificates.
Attackers can exploit digital certificates to:
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Issue new certificates.
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Impersonate legitimate users and services.
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Intercept communications via man-in-the-middle techniques.
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Escalate privileges.
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Bypass security controls that rely on certificate validation.
Let’s try and request the administrator’s certificate template and save the private key, which can later be used to escalate privileges and gain access to critical resources.
Certificates are critical for accessing digital resources in a secure manner. But they can be misconfigured, and attackers discover these vulnerabilities and exploit them to steal certificates, escalate privileges, impersonate users, or forge new certificates on the domain.
Want to learn more on how to secure ADCS and prevent misconfigurations? Tune into our webinar on Protecting Active Directory from ADCS exploits.
