Notifications
Clear all
Topic starter 01/08/2025 9:41 pm
🔐 Microsoft Domain Certificates are digital credentials used within a Windows domain to securely authenticate users, computers, and services. They’re part of a broader Public Key Infrastructure (PKI) managed by Active Directory Certificate Services (AD CS).
🧠 What They Do
- Authenticate identities: Prove that a user or device is who they claim to be
- Enable secure communication: Encrypt data between clients and servers
- Support smartcard logon, VPN, Wi-Fi, and Windows Hello for Business
- Facilitate single sign-on (SSO) and seamless access across domain resources
🏢 Where They’re Used
| Use Case | Certificate Role |
|---|---|
| Domain Controller | Validates identity during logon |
| Client Devices | Authenticates to domain securely |
| Web Servers (IIS) | Enables HTTPS and secure sessions |
| Email (Exchange) | Encrypts and signs messages |
| Remote Access (VPN) | Secures connections with certificate-based auth |
🛠️ How They’re Issued
- Managed by AD CS, which acts as a Certificate Authority (CA)
- Certificates are issued based on templates that define usage and permissions
- Can be auto-enrolled via Group Policy for seamless deployment
🧪 Example: Domain Controller Certificate
A domain controller might use a certificate with:
- Subject Alternative Names (SANs) matching its DNS name
- Key Usage: Digital signature, key encipherment
- Enhanced Key Usage (EKU): Smartcard logon, server authentication, KDC authentication
This allows it to support modern authentication methods like smartcards and Windows Hello for Business.
⚠️ Security Updates & Enforcement
Microsoft has been tightening certificate-based authentication:
- Strong certificate mapping enforcement began in 2025
- Certificates must meet stricter criteria or authentication will fail
- Admins must audit and update certificates to avoid outages
