There appears to be a bug in the latest Windows 11 26H1 (no, that’s not a typo – 26H1) build affecting Protected Extensible Authentication Protocol (PEAP). In my testing, all VPN connection attempts (Always On VPN and manual/ad-hoc) failed when PEAP was used for authentication.
Windows 11 26H1
Recently, while reviewing downloads and product keys in Visual Studio, I noticed a new Windows 11 release listed: Windows 11 26H1 (business and consumer editions). I initially thought 26H1 would be ARM-only, but the download is available for x64 as well.
I’m not sure whether this is intended as a general release, because Microsoft describes it as an Insider Experimental Preview Build (28200.1873). I also don’t recall seeing Insider builds offered through Visual Studio downloads, so I’m not sure what to make of it. Either way, if you’re evaluating this build, the notes below document a VPN issue I was able to reproduce.
Troubleshooting
After preparing a Windows 11 26H1 test client, I found that the Always On VPN user tunnel would not connect. The same configuration worked on earlier Windows 11 versions. In the event log, I observed the following errors.
Error 619
When using SSTP, the event log records error code 619 (event ID 20227) from the RasClient event source, with the following error message.
The user [domain\user] dialed a connection named [connection name] which has failed. The error code returned on failure is 619.
Error 691
When using IKEv2, the event log records error code 691 (event ID 20227) from the RasClient event source, with the following error message.
The user [domain\user] dialed a connection named [connection name] which has failed. The error code returned on failure is 691.
Workaround
At the time of writing, the only workaround I’ve found to restore Always On VPN connectivity is to switch authentication from PEAP to EAP-TLS. This may not be a drop-in change for every environment, so evaluate the security and operational impact before rolling it out broadly. You’ll need to enable EAP-TLS on both the client and the NPS/RADIUS server.
Summary
I’m not convinced Windows 11 26H1 will be widely deployed soon, since it appears to be an experimental/Insider build rather than a general release. If you decide to evaluate it, plan to use the workaround above to maintain Always On VPN connectivity.
Feedback
Have you tested Always On VPN with Windows 11 26H1? If so, do you see the same behavior? Share your findings in the comments.
Recently, I wrote about Microsoft Always On VPN and Entra Conditional Access and how conditional access improves your organization’s security posture by making policy-based access decisions based on various signals such as user identity, location, device compliance, platform, sign-in risk, and more. In this post, I’ll provide step-by-step instructions for integrating Entra Conditional Access with existing Always On VPN deployments.
Requirements
To use Microsoft Entra Conditional Access with Always On VPN you must have Entra ID P1 at a minimum. To use advanced features such as risk-based policy assessment, you must have Entra ID P2. In addition, all endpoints must be under Intune management; either native Entra ID joined, or hybrid Entra ID joined.
Enable VPN Support
To begin, open the Microsoft Entra admin center (https://entra.microsoft.com/), navigate to Identity > Protection > Conditional Access, and perform the following steps.
Click VPN Connectivity.
Click New certificate.
From the Select duration drop-down list, choose an appropriate certificate validity period.
Click Create.
Once complete, click Download certificate and copy the certificate file to a domain-joined system on-premises.
Publish Certificate
Next, administrators must publish the Entra VPN root certificate in Active Directory to support domain authentication. Open an elevated PowerShell or command window and run the following commands.
certutil.exe -dspublish -f <path to certificate file> RootCA
certutil.exe -dspublish -f <path to certificate file> NtAuthCA
Note: You must be a domain administrator to perform this task.
Conditional Access Policy
Navigate to Identity > Protection > Conditional Access and click Policies, then perform the following steps to create a conditional access policy for VPN access.
Click New Policy.
Enter a descriptive name for the new policy.
Click the link in the Target resources section.
From the Select what this policy applies to drop-down list, select Resources (formerly cloud apps).
In the Include section, choose Select resources.
Click the link in the Select section.
Enter VPN in the search field.
Check the box next to VPN Server.
Click Select.
Click the link in the Grant section.
Select Grant access.
Check the box next to Require device to be marked as compliant.
Click Select.
On the Enable policy slider, select On.
Click Create.
NPS
Changes to Network Policy Server (NPS) policy and configuration are required to support Always On VPN with Entra Conditional Access.
NPS Policy
To update the Always On VPN network policy to support Entra Conditional Access, open the NPS management console (nps.msc), expand Policies, then select Network Policies and perform the following steps.
Right-click on the Always On VPN policy and choose Properties.
Select the Settings tab.
Select Vendor Specific in the RADIUS Attributes section.
Click Add.
Select the Allowed-Certificate-OID attribute.
Click Add.
Click Add.
Enter 1.3.6.1.4.1.311.87 in the Attribute value field.
Click Ok.
Click Ok.
Click Close.
Click Ok.
Important Note: This change will block new Always On VPN user tunnel connections until you update the client configuration. When integrating an existing Always On VPN implementation with Entra Conditional Access, consider creating a new NPS policy and corresponding security group to migrate users to conditional access seamlessly.
NPS Configuration
By default, NPS will perform revocation checks for certificates used for domain authentication. However, Entra Conditional Access uses short-lived certificates (one-hour lifetime) that do not include CRL Distribution Point (CDP) information. Therefore, administrators must change the NPS server configuration to disable revocation checking for certificates lacking this information.
To do this, open the registry editor (regedit.exe) and create a new registry key with the following settings.
Once complete, the server must be rebooted for the change to take effect.
Client Configuration
After making all required changes to the supporting infrastructure, you must also update the Always On VPN client configuration to leverage Entra Conditional Access. Changes to client configuration vary depending on the method used to deploy and manage Always On VPN client configuration settings.
Intune
When using Microsoft Intune and the native VPN policy type to deploy and manage Always On VPN client configuration settings, perform the following steps to update the VPN configuration to include Entra Conditional Access support.
Click Enable next to Conditional access for this VPN connection.
Click Enable next to Single sign-on (SSO) with alternate certificate.
Enter Client Authentication in the Name field.
Enter 1.3.6.1.5.5.7.3.2 in the Object Identifier field.
Enter the organization’s root certification authority (CA) certificate thumbprint in the Issuer hash field.
XML
When using a custom XML configuration file for Always On VPN client configuration settings deployed using Intune or PowerShell, edit the XML file, remove the existing <TLSExtensions></TLSExtensions> section, and replace it with the following.
In addition, add the following code between the <VPNProfile></VPNProfile> tags after <TrustedNetworkDetection>.
Note: You will find a sample XML configuration file you can copy and paste from on GitHub here.
DPC
When using Always On VPN Dynamic Profile Configurator (DPC) for managing Always On VPN client configuration settings, open the DPC group policy and navigate to Computer Configuration > Policies > Administrative Templates > DPC Client > User Tunnel Settings > Advanced and perform the following steps.
Following the guidance in this post to integrate Entra Conditional Access with Always On VPN can significantly improve your organization’s security posture. In the example above, the conditional access policy is a basic one. Yet, it dramatically reduces the attack surface for your remote access infrastructure by ensuring only compliant devices can establish a VPN connection.
Administrators can use advanced conditional access policy settings to strengthen the VPN’s security further by performing additional checks, such as requiring strong, phishing-resistant credentials and requesting multifactor authentication (MFA) for risky sign-ins.
Microsoft introduced changes to Windows domain controllers in the February 2025 security update that may result in authentication failures for Always On VPN user tunnel connections. If you suddenly find that all your Always On VPN user tunnel connections fail, additional changes may be required to resolve the issue.
Authentication Failure
Administrators may find that Always On VPN connections fail after applying the February 2025 Microsoft security updates. Specifically, users may receive the following warning message.
“The remote access connection completed, but authentication failed because the certificate that authenticates the client to the server is not valid. Ensure that the certificate used for authentication is valid.”
Error 853
Administrators will also find a corresponding event log entry with event ID 20227 from the RasClient source with the following error message.
“The user <username> dialed a connection named <connection name> which has failed. The error code returned on failure is 853.”
NPS Events
The event log on the NPS server will also record event ID 6273 from the Microsoft Windows security auditing source with the following error message.
“Network Policy Server denied access to a user.”
The authentication details of the event include Reason Code 16 with the following reason.
“Authentication failed due to a user credentials mismatch. Either the user name provided does not map to an existing user account or the password was incorrect.”
DC Events
If the issue is related to changes implemented to domain controllers in the February 2025 security update, administrators will also find a corresponding event log entry on a domain controller with event ID 39 from the Kerberos-Key-Distribution-Center source with the following error message.
“The Key Distribution Center (KDC) encountered a user certificate that was valid but could not be mapped to a user in a secure way (such as via explicit mapping, key trust mapping, or a SID). Such certificates should either be replaced or mapped directly to the user via explicit mapping.”
Root Cause
The above conditions indicate that a user attempted to authenticate to the VPN with a certificate that was not strongly mapped. Most likely, the certificate was issued using Microsoft Intune with SCEP or PKCS. This results from changes made to domain controllers in the February 2025 security update that requires certificates used for Active Directory authentication to be strongly mapped. Until now, domain controllers allowed access and only logged an event in the event log when a certificate did not include strong certificate mapping. The February 2025 security update now enforces strong certificate mapping, and authentication requests will fail without it.
Resolution
Administrators must issue new certificates that are strongly mapped to resolve this issue. For certificates issued with PKCS, changes are required on the Intune Certificate Connector server before re-issuing. For certificates issued with SCEP, changes to the device configuration policy are required. See the post Strong Certificate Mapping for Intune PKCS and SCEP Certificates for more details.
Workaround
Re-issuing certificates takes time. To restore connectivity immediately, administrators can implement the following registry settings on all domain controllers to switch back to audit mode and allow authentication without strong certificate mapping.
I recommend deploying this setting via GPO assigned to the Domain Controllers OU. However, you can also implement this change using PowerShell if necessary.
I’m excited to announce that I’ll be speaking at the Arizona Systems Management User Group (AZSMUG) at their next user group meeting on Friday, March 7, at 9:00 AM MST. I am presenting on the topic of Certificate Deployment Strategies with Microsoft Intune.
Intune and Certificates
My session at AZSMUG will provide an overview of issuing and managing certificates with Microsoft Intune. We’ll begin by examining common scenarios for certificate authentication and explore various delivery methods, including PKCS and SCEP. Additionally, we’ll discuss supporting technologies such as the Network Device Enrollment Service (NDES) and review deployment strategies and high availability options for the Intune Certificate Connector. The session will also cover Cloud PKI for Intune, integration with on-premises Active Directory, and best practices for securing certificate lifecycles and key management in enterprise environments.
Register Now
If you are in the Phoenix area and would like to attend the user group meeting on Friday, March 7, you will find the registration link here. Hope to see you there!
Are you ready? In just a few short weeks(!) Microsoft will release the February 2025 security updates. This is a critical update because Microsoft plans to enable full enforcement of strong certificate mapping on Active Directory Domain Controllers (DCs) with this release. Administrators unprepared for this may incur outages for workloads using certificate-based authentication such as Always On VPN, Wi-Fi, and others.
Microsoft introduced strong certificate mapping with the May 2022 update KB5014754 to address vulnerabilities identified with certificate-based authentication. The update makes changes to Active Directory Certificate Services (AD CS) certification authorities (CAs) to embed the principal’s Security Identifier (SID) on issued certificates with a new certificate extension. The update also changes domain controller behavior to monitor and optionally enforce strong certificate mapping for authentication.
Enforcement Mode
When first introduced, the update is configured in compatibility mode. If a certificate that isn’t strongly mapped is presented for authentication, an event is recorded in the event log indicating that. Microsoft has been planning for years to enable full enforcement. After many delays, that time is now upon us. Specifically, full enforcement for strong certificate mapping will be enabled by default on DCs after applying the February 2025 security updates.
Note: Administrators can switch back to compatibility mode for now. See below for more details.
Limitations
Initially, the strong certificate mapping update was applied only to online certificate templates. Specifically, those templates are configured to build the subject name from Active Directory information. However, offline templates, where the subject name is supplied in the request, do not include this information by default. Crucially, any certificate issued with Microsoft Intune with PKCS or SCEP uses offline templates and is not strongly mapped. The lack of strong certificate mapping options for Intune-issued certificates forced Microsoft to delay its full enforcement deadline until these limitations were resolved.
Updates
In October 2024, Microsoft Intune announced support for strong certificate mapping for PKCS and SCEP certificates. Administrators can now configure these certificates to include strong certificate mapping. However, administrators must take action to affect this change.
PKCS
To enable strong certificate mapping for PKCS certificates, administrators must ensure that the certificate connector is running at least version 6.2406.0.1001. In addition, the following registry key must be configured on the connector server.
The Intune Certificate Connector server must be restarted for this change to take effect. No changes are required on the PKCS certificate policy in Intune.
SCEP
To enable strong certificate mapping for SCEP certificates, administrators must add the following attribute/value pair to the Subject alternative name settings on their existing Intune SCEP certificate policy.
Attribute: URI Value: {{OnPremisesSecurityIdentifier}}
Preparation
Administrators using certificate-based authentication against on-premises Active Directory should ensure all user and device authentication certificates include embedded SID information. For certificates issued on-premises, with Intune using PKCS or certificates issued by Entra Conditional Access, the certificate should now have the extension 1.3.6.1.4.1.311.25.2, including the principal’s SID.
SCEP certificates issued using Intune will include the following information in the Subject Alternative Name field.
URL=tag:microsoft.com,2022-09-24:sid:<sid>
Note: This applies to certificates issued using Cloud PKI for Microsoft Intune as those certificates are deployed using a SCEP device configuration policy.
Opt-Out
With the February 2025 security update, all domain controllers will be switched to full enforcement mode. Authentication requests using certificates without strong mapping will be denied in this configuration.
If your organization is not prepared to move to full enforcement mode, the February 2025 update allows administrators to opt out and switch back to compatibility mode by enabling the following registry key on all domain controllers.
Administrators are strongly encouraged to update all user and device authentication certificates before September 2025. With the September 2025 security update, Microsoft will no longer honor the opt-out registry settings and strictly enforce strong certificate mapping for all certificate-based authentication requests.
Troubleshooting
Certificate authentication is commonly used for Always On VPN and Wi-Fi authentication. If full enforcement mode is enabled on domain controllers and a certificate is presented for authentication that is not strongly mapped, administrators may see the following event log information recorded on the Network Policy Server (NPS).
Network Policy Server denied access to a user.
The details of the event include the following.
Reason Code: 16 Reason: Authentication failed due to a user credentials mismatch. Either the user name provided does not map to an existing user account or the password was incorrect.
Obviously, the user does not enter their password when using certificates for authentication. However, the indication of a credential mismatch can be caused by missing strong certificate mapping information when the DC is in full enforcement mode.
Note: There are other causes for reason code 16 failures on NPS. Further investigation may be required to determine the root cause.
Microsoft Cloud PKI for Intune is a PKI-as-a-Service offering that allows organizations to issue and manage digital certificates without on-premises infrastructure. Certificates are excellent phishing-resistant credentials that are well-suited for applications requiring strong authentication, such as secure remote access with Always On VPN. However, administrators may encounter errors when attempting to authenticate users or devices using certificates issued by Cloud PKI for Intune.
Error 853
After publishing certificates with Cloud PKI for Intune and configuring the on-premises Always On VPN infrastructure to support this, administrators will find that the Always On VPN connection fails to connect. Attempts to manually start the connection result in the following error message.
“The remote access connection completed, but authentication failed because the certificate that authenticates the client to the server is not valid. Ensure the certificate used for authentication is valid.”
In the event log on the Windows client, you’ll find an event ID 20227 from the RasClient source that includes the following error message.
“The user <domain>\<user> dialed a connection named <VPN connection name> which has failed. The error code returned on failure is 853.”
Error 853 (ERROR_EAP_USER_CERT_INVALID) indicates the user certificate is invalid.
Certificate
Upon further investigation, the certificate shows no issues, is valid, is trusted, and has a private key.
NPS
Looking at the event log on the Network Policy Server (NPS), you’ll find a corresponding event ID 6273 from the Microsoft Windows security auditing source that includes the following error message.
“Network Policy Server denied access to a user.”
Looking at the authentication details section of this event log entry yields the following important clue.
Reason Code: 258 Reason: The revocation function was unable to check revocation for the certificate.
Failed Revocation Check
Since the NPS server indicates that it rejected the authentication request because it could not perform a revocation check, let’s bring the user authentication certificate to the NPS server and perform some tests.
Export Certificate
Open the user certificate store (certmgr.msc) on the client and expand Personal > Certificates. Right-click on the certificate in question and choose All Tasks > Export. Export the certificate only (not the private key) and copy the file to the NPS server.
Verify Certificate
Open a PowerShell or command window on the NPS server and run the following command to validate the certificate.
certutil.exe -verify -urlfetch <path to exported certificate>
For example.
certutil.exe -verify -urlfecth .\rdeckard.cer
The command generates a lot of output, but if you look at the very end of the data stream, you’ll see two interesting items.
Revocation check skipped – no revocation information available
Leaf certificate revocation check passed
Based on this information the user certificate (the leaf certificate) passed a revocation check. However, it would appear that another certificate in the chain does not include revocation information. Since there is only a root and issuing CA in the chain, and root certificates don’t include revocation information because they are the self-signed root of trust, it would appear that revocation information is missing from the issuing CA certificate.
We can confirm this by scrolling up in the previous command’s output to where the verification of the issuing CA certificate takes place. Here, you’ll see that the issuing CA certificate is missing CDP (CRL Distribution Point) information.
When NPS attempts to validate the certificate and the certificate chain, it expects to find CDP information, which it will use to check if the issuing CA certificate has been revoked. The revocation check fails without this information, and the authentication request is rejected.
Design Error?
Missing CDP information is not unusual for end-entity (leaf) certificates when they are short-lived. An example is Entra ID conditional access certificates, which do not include CDP information by design. However, I expect this information to be listed on an issuing CA certificate. Why it’s not there, I’m not sure. I’ll investigate this in more depth and report on anything I learn that’s new.
Workaround
To move forward using Cloud PKI for Intune certificates with Always On VPN, administrators must implement the following registry setting on all NPS servers handling authentication requests for Always On VPN servers.
Key = HKLM\SYSTEM\CurrentControlSet\Services\RasMan\PPP\EAP\13 Name = IgnoreNoRevocationCheck Type = DWORD Value = 1
To implement this change using PowerShell, open an elevated PowerShell command window and run the following command.
Microsoft released an update for the Windows Server Network Policy Server (NPS) to address recently disclosed vulnerabilities in the Remote Access Dial-In User Service (RADIUS) protocol in the July 2024 security updates. RADIUS is an industry-standard authentication protocol widely used for remote access, including Always On VPN. The RADIUS protocol was first introduced in the early 1990s and, unfortunately, still relies on the deprecated MD5 cryptographic hash function. The good news is that this vulnerability does not affect Always On VPN. Read on to learn more.
Blast-RADIUS
Blast-RADIUS is an attack on the RADIUS protocol that allows an attacker to alter network authentication packets to gain access to a service relying on RADIUS for authentication by exploiting the weakness of MD5 integrity checks in RADIUS. In the absence other controls, an attacker could alter an authentication response and change the reply from Access-Reject to Access-Accept.
Considerations
It’s important to note that leveraging this attack is not trivial. It requires local network access, so the attacker must have a presence on the target network to carry out this attack. However, cloud-hosted RADIUS services are inherently more vulnerable. In addition, the attack is mostly academic today because the default timeout for authentication requests is typically short, usually between 5 and 30 seconds. This is not enough time (today) for an attacker to mount the attack. However, this attack could become more feasible if authentication timeouts are increased (sometimes required to support MFA) or if an attacker has access to vast computing resources.
Affected Protocols
Although Blast-RADIUS is a vulnerability in the RADIUS protocol itself, not all authentication protocols are affected. Specifically, this vulnerability affects services leveraging PAP, CHAP, MS-CHAP, and MS-CHAPv2. Extensible Authentication Protocol (EAP) and Protected Extensible Authentication Protocol (PEAP) are not vulnerable to this attack. Since Always On VPN requires EAP authentication, it is not susceptible to this attack.
Mitigation
Microsoft has published guidance in KB5040268 for mitigating Blast-RADIUS attacks on Windows NPS servers. Specifically, administrators are encouraged to enable the Message-Authenticator attribute in Access-Request packets sent by the network access server and to ensure the NPS server requires the Message-Authenticator attribute in any Access-Request messages it receives.
Note: The following changes are not required for Always On VPN or any other workload using EAP-TLS or Protected EAP, as these protocols use TLS natively to protect the authentication exchange.
NPS
To configure this setting in the UI, open the NPS management console (nps.msc) and perform the following steps.
Expand RADIUS Clients and Servers.
Highlight RADIUS Clients.
Right-click the RADIUS client to configure and choose Properties.
Select the Advanced tab.
Check the box next to Access-Request messages must contain the Message-Authenticator attribute.
PowerShell
To configure this setting using PowerShell, open an elevated PowerShell command window and run the following command.
Administrators should also run the following commands on their NPS servers to further protect their infrastructure from Blast-RADIUS attacks.
netsh.exe nps set limitproxystate all = enable
netsh.exe nps set requiremsgauth all = enable
RRAS
When using Windows Server Routing and Remote Access (RRAS) without EAP, ensure the RADIUS server configuration always includes the Message-Authenticator. To configure this setting, open the Routing and Remote Access console (rrasmgmt.msc) on the RRAS server and perform the following steps.
Right-click the VPN server and choose Properties.
Select the Security tab.
Click the Configure button next to the Authentication provider drop-down list.
Highlight the RADIUS server and choose Edit.
Check the box next to Always use message authenticator.
Repeat these steps for any additional configured RADIUS servers.
CLI
Administrators can implement this change at the command line by opening an elevated command window and entering the following command.
netsh.exe ras aaaa set authserver name = <name of RADIUS server> signature = enabled
For example:
netsh.exe ras aaaa set authserver name = nps.lab.richardhicks.net signature = enabled
New NPS Events
After installing the KB5040268 update on NPS servers, the NPS server will record event ID 4421 from the NPS source after a service start if the RequireMsgAuth or LimitProxyState settings are not configured.
“RequireMsgAuth and/or limitProxyState configuration is in Disable mode. These settings should be configured in Enable mode for security purposes.”
Optional Mitigation
If administrators cannot configure the above settings, consider using IPsec to secure network traffic at the transport layer. IPsec will protect all RADIUS traffic at the network layer to mitigate Blast-RADIUS attacks. Unfortunately, Windows Server NPS does not support TLS or DTLS, so IPsec is your only option.
Summary
Always On VPN is not vulnerable to the Blast-RADIUS attack. However, NPS is commonly a shared service in many organizations, and other workloads may use older, vulnerable protocols. Consider implementing the changes detailed in KB5040268 as outlined in above to ensure the integrity of your environment and mitigate these potential attacks.
Always On VPN administrators deploying on-premises enterprise PKI certificates using Microsoft Intune with PKCS may encounter a scenario where a certificate fails to be issued to a user or device. In this post, I’ll share some things to investigate when troubleshooting this issue.
Event 1001
To begin, open the Event Log and navigate to Applications and Services > Microsoft > Intune > CertificateConnectors > Admin. You will likely find an event ID 1001 from the CertificateConnectors source with the following error message.
Failed to process PKCS request.
Prerequisites
Validate the following prerequisites have been met on the issuing Certification Authority (CA) server.
Certificate Template
Ensure the certificate template used for PKCS has the correct permissions and is published on an issuing CA server. Open the Certificate Templates management console (certtmpl.msc), right-click the certificate template, choose Properties, and then click on the Security tab. The certificate template must grant the Intune Certificate connector server’s computer account (or the PKCS connector’s service account if running as a service and not SYSTEM) the Read and Enroll permissions on the template.
CA Permissions
In addition to the permissions on the certificate template, ensure the correct permissions have been configured on the issuing CA itself. Right-click on the CA in the Certification Authority management console (certsrv.msc) and choose Security. Ensure the Intune Certificate connector server’s computer account (or the PKCS connector’s service account, if running as a service and not SYSTEM) is granted The Issue and Manage Certificates and Request Certificates permissions.
Intune Policy
Ensure the Intune device configuration policy is configured correctly. These three fields are critical and can result in failed PKCS certificate deployment if misconfigured.
Certification Authority
Enter the fully qualified domain name (FQDN) of the on-premises issuing CA server in this field.
Certification Authority Name
Enter the common name of the issuing CA in this field. You will find this information by running the following command on any domain-joined Windows system.
certutil.exe -dump
Certificate Template Name
Enter the name of the certificate template in Active Directory. Be aware that the template name and template display name are two different things. The template name is usually the template display name without spaces. However, that’s not a guarantee. On the General tab of the certificate template, look at the template name field on the certificate template to confirm.
Summary
This article is not a comprehensive troubleshooting guide for problems associated with failed PKCS certificate deployment using the Microsoft Intune Certificate connector and PKCS. However, it covers some of the more common problems administrators will likely encounter. If you cannot provision PKCS certificates correctly, drop me a note and I’ll provide further guidance.
Recently, Microsoft introduced the general availability of its new PKI-as-a-service solution called Microsoft Intune Cloud PKI. Cloud PKI allows administrators to issue and manage user and device authentication certificates for Intune-managed endpoints without deploying Active Directory Certificate Services (AD CS) on-premises. Cloud PKI frees administrators from the burdens of deploying and managing AD CS, including the complicated Network Device Enrollment Service (NDES) server configuration required for Simple Certificate Enrollment Protocol (SCEP) certificate deployment with Intune.
Advantages
Microsoft Intune Cloud PKI offers many significant advantages over traditional on-premises AD CS deployments.
No Infrastructure
The most obvious advantage of using Cloud PKI is that you do not have to deploy and manage your own Certification Authority (CA). Although implementing AD CS isn’t that difficult, managing and operating a CA infrastructure securely can be quite challenging. In addition, a high-security AD CS deployment utilizes hardware secure modules (HSMs) to protect CA private keys, which are quite expensive and sometimes difficult to support.
Cloud-Hosted SCEP
Removing the requirement to configure and deploy your own NDES server to support SCEP certificates is certainly a welcome advantage. NDES is notoriously difficult to configure, secure, and troubleshoot when it doesn’t work correctly. Cloud PKI includes cloud hosted SCEP services that are highly available and redundant within the Microsoft Azure infrastructure.
Automatic Revocation
Cloud PKI automates the deployment of certificates to Intune-managed users and devices and automatically revokes certificates when they fall out of scope. Administrators can also manually revoke certificates using the Intune management console.
Reporting
Administrators can easily view the status of Cloud PKI-issued certificates in Intune. The UI shows the active, expired, and revoked certificates for the issuing CA.
Clicking View all certificates shows a detailed list of all certificates.
BYOCA
Another compelling feature of Cloud PKI is Bring Your Own CA (BYOCA). This feature enables administrators to deploy a cloud-hosted CA that is chained to their existing on-premises AD CS root CA. This is helpful for scenarios where AD CS is already in place and used to issue and manage certificates to existing domain-joined clients and servers. BYOCA effectively allows you to extend your existing CA infrastructure to the cloud and use Cloud PKI to issue and manage certificates for your Intune-managed endpoints while maintaining the full functionality and feature set of on-premises AD CS for non-Intune-managed devices.
Limitations
Although there are many advantages to Cloud PKI, there are some limiting factors to consider.
RSA Only
Today, Cloud PKI is limited to RSA keys only. Administrators can create CAs using RSA 2048, 3072, or 4096-bit keys. Elliptic Curve (EC) keys are not currently supported in Cloud PKI.
Intune Devices Only
Cloud PKI is limited to issuing certificates to Intune-managed devices only. Endpoints must be Entra-joined, or hybrid Entra-joined to enroll for certificates using Cloud PKI.
Inflexible Configuration
The Cloud PKI root and issuing CAs cannot be reconfigured after deployment. Since Cloud PKI root and issuing CAs don’t support the Any Purpose EKU (2.5.29.37.0), all EKUs must be defined when the CA is created. If, in the future, an administrator requires an EKU that was not present when the CA was deployed, an entirely new hierarchy (root and issuing CA) must be deployed.
Cost
There’s been much discussion about the cost associated with Cloud PKI. Cloud PKI can be licensed as part of the Intune Suite, which is $10.00 per user per month. Cloud PKI licenses will also be available as a standalone add-on for $2.00 per user per month. For large organizations, this might be cost-prohibitive.
Summary
Overall, Microsoft Intune Cloud PKI is a welcome addition to the Microsoft suite of cloud services. Certificates are excellent phishing-resistant credentials that can be used to improve security for organizations of all sizes. However, managing a CA can be tedious and time-consuming. Leveraging the cloud for PKI and certificate management will be helpful in many scenarios. However, Cloud PKI has some potential drawbacks, and many may not fit everyone.
More Information
Want to learn more about Microsoft Intune Cloud PKI and how it can benefit your organization? Take the first step towards streamlined certificate management and enhanced security for your organization. Fill out the form below, and I’ll provide more information about using Intune Cloud PKI to safeguard your digital assets confidently.
A question that occasionally arises when I’m conducting an Always On VPN planning and design workshop for a customer is static IP address assignment options for VPN connections. Typically, the use case is a specific user that requires special access to a sensitive system internally. Assigning a static IP address to the user allows administrators to create firewall rules restricting access to this connection.
Static IP Assignment
Assigning a static IP address to a user is accomplished by editing the properties of their user account in Active Directory. Open the Active Directory Users and Computers console (dsa.msc), navigate to the Dial-in tab on the target individual’s Active Directory user account, and check the box next to Assign Static IP Addresses.
Next, click the Static IP Addresses button, check the box next to Assign a Static IPv4 address, and enter an IP address. Optionally, check the box next to Assign a static IPv6 address and enter a prefix and Interface ID, if required.
NPS Configuration
Once the user account in Active Directory is configured with a static IP address assignment, each NPS server in the organization must be registered in Active Directory. More details on Active Directory registration for NPS servers can be found here.
Caveats
Assigning static IP addresses to VPN users has many drawbacks and limitations. Consider the following.
Device IP
Assigning a static IP address to a device is not supported. You can only assign a static IP address to a user in Active Directory.
Address Assignment
The IP address you assign to the user must be from the same subnet as the VPN server’s internal network interface. If there is more than one VPN server, all VPN servers must be on the same subnet.
Multisite
Assigning static IP addresses to users is not supported when VPN servers are deployed in multiple locations.
Concurrent Sessions
Users with a static IP address assignment must only log on to one device at a time. If a user attempts to log in to multiple devices simultaneously, subsequent connections will fail due to the duplicate IP address assignment.
NPS
Always On VPN administrators may have discovered the option to assign a static IP address using NPS policy. Unfortunately, this option is severely limited. A separate NPS policy is needed for each user that requires a static IP address. However, NPS does not support assigning NPS policies to users, only groups. Technically speaking, you could create a separate group for each user needing a static IP address, but that’s not scalable. Also, it offers no real advantage over using the Active Directory method described above.
Summary
Although it’s possible to assign a static IP address to a user, there is currently no option to assign a static IP address to a device. In addition, static IP address assignment imposes other limitations that make the option challenging. Also, the inability to connect to geographically dispersed VPN servers is severely limiting.
