Troubleshooting Always On VPN Error Code 0x80092013

Troubleshooting Always On VPN Error Code 0x80092013Windows Server Routing and Remote Access Service (RRAS) is commonly used for Windows 10 Always On VPN deployments because it is easy to configure and manage and it includes Microsoft’s proprietary Secure Socket Tunneling Protocol (SSTP). SSTP is a Transport Layer Security (TLS) VPN protocol that is firewall-friendly and ubiquitously available. However, a common configuration mistake can lead to failed connections.

Error 0x80092013

A Windows 10 Always On VPN client may fail to establish a VPN connection to an RRAS VPN server when using SSTP. The VPN client will return the following error message.

“Can’t connect to Always On VPN. The revocation function was unable to check revocation because the revocation server was offline.”

Troubleshooting Always On VPN Error Code 0x80092013

The event log will also include RasClient event ID 20227 with the following error.

“The user [domain\user] dialed a connection named [connection name] which has failed. The error code returned on failure is -2146885613.”

Troubleshooting Always On VPN Error Code 0x80092013

The Win32 error code –2146885613 converts to hexadecimal 0x80092013, which translates to CRYPT_E_REVOCATION_OFFLINE, indicating that the client was unable to successfully perform a check of the VPN server’s SSL certificate.

Revocation Checking

When the VPN client attempts to establish an SSTP connection to the Windows RRAS VPN, it will check the Certification Revocation List (CRL) using the information provided in the SSL certificate. If the CRL is unreachable for any reason, the client will not complete the connection

Common Cause of Error 0x80092013

Certificate revocation failures for Windows 10 Always On VPN SSTP connections commonly occur when the RRAS VPN server is configured with an SSL certificate issued by an internal certification authority (CA) and the CRL is not publicly available.

Resolving Error 0x80092013

Making the internal CA’s CRL available publicly will of course resolve this error. However, best practice recommendations for the SSTP SSL certificate call for the use of a certificate issued by a public CA. For detailed information about SSL certificate requirements and recommendations, please see Always On VPN SSL Certificate Requirements for SSTP.

Additional Information

Always On VPN SSL Certificate Requirements for SSTP

Always On VPN ECDSA SSL Certificate Request for SSTP

Always On VPN Protocol Recommendations for Windows RRAS

Always On VPN ECDSA SSL Certificate Request for SSTP

As I’ve discussed previously, it is strongly recommended that the TLS certificate used for SSTP be signed using the Elliptic Curve Digital Signature Algorithm (ECDSA). ECDSA provides better security and performance compared to RSA certificates for Windows 10 Always On VPN connections using SSTP. See my previous post Always On VPN SSL Certificate Requirements for SSTP for more information.

Certificate Signing Request

To generate a Certificate Signing Request (CSR) using ECDSA to send to a public Certification Authority (CA), open the local computer certificate store (certlm.msc) on any Windows server or client and follow the steps below.

  1. Expand Certificates – Local Computer.
  2. Right-click the Personal folder and choose All Tasks > Advanced Operations > Create Custom Request.
  3. Click Next.
  4. Click Next.
  5. From the Template drop-down list choose (No template) CNG key.
  6. Click Next.
  7. Click Details.

    Always On VPN ECDSA SSL Certificate Request for SSTP

  8. Click Properties.
  9. On the General tab enter a name in the Friendly name field.
  10. Click on the Subject tab.
    1. In the Subject name section, from the Type drop-down list choose Common name.
    2. In the Value field enter the VPN server’s public hostname and click Add.
    3. In the Alternative name section, from the Type drop-down list choose DNS.
    4. In the Value field enter the VPN server’s public hostname and click Add.

      Always On VPN ECDSA SSL Certificate Request for SSTP

  11. Click on the Private Key tab.
    1. Expand Cryptographic Service Provider.
    2. Uncheck RSA,Microsoft Software Key Storage Provider.
    3. Check ECDSA_P256,Microsoft Software Key Storage Provider.

      Always On VPN ECDSA SSL Certificate Request for SSTP

  12. Click Ok.
  13. Click Next.
  14. Enter a name for the file in the File Name field.
  15. Click Finish.

Submit the Request

Once complete, submit the CSR for signing to your favorite public CA. Based on my experience, some CAs are easier to obtain ECDSA-signed certificates than other. Today, Digicert seems to be one of the better public CAs for obtaining EC TLS certificates.

Complete the Request

Once the CA has issued the certificate, import the certificate in to the local computer certificate store on the same client or server where the original CSR was created. The certificate can then be exported and imported on additional VPN servers, if required.

Additional Information

Always On VPN SSL Certificate Requirements for SSTP

Always On VPN Protocol Recommendations for RRAS

 

Always On VPN SSL Certificate Requirements for SSTP

Always On VPN Certificate Requirements for SSTPThe Windows Server 2016 Routing and Remote Access Service (RRAS) is commonly deployed as a VPN server for Windows 10 Always On VPN deployments. Using RRAS, Always On VPN administrators can take advantage of Microsoft’s proprietary Secure Socket Tunneling Protocol (SSTP) VPN protocol. SSTP is a Transport Layer Security (TLS) based VPN protocol that uses HTTPS over the standard TCP port 443 to encapsulate and encrypt communication between the Always On VPN client and the RRAS VPN server. SSTP is a firewall-friendly protocol that ensures ubiquitous remote network connectivity. Although IKEv2 is the protocol of choice when the highest level of security is required for VPN connections, SSTP can still provide very good security when implementation best practices are followed.

SSTP Certificate

Since SSTP uses HTTPS for transport, a common SSL certificate must be installed in the Local Computer/Personal/Certificates store on the RRAS VPN server. The certificate must include the Server Authentication Enhanced Key Usage (EKU) at a minimum. Often SSL certificates include both the Server Authentication and Client Authentication EKUs, but the Client Authentication EKU is not strictly required. The subject name on the certificate, or at least one of the Subject Alternative Name entries, must match the public hostname used by VPN clients to connect to the VPN server. Multi-SAN (sometimes referred to as UC certificates) and wildcard certificates are supported.

Always On VPN Certificate Requirements for SSTP

Certification Authority

It is recommended that the SSL certificate used for SSTP be issued by a public Certification Authority (CA). Public CAs typically have their Certificate Revocation Lists (CRLs) hosted on robust, highly available infrastructure. This reduces the chance of failed VPN connection attempts caused by the CRL being offline or unreachable.

Using an SSL certificate issued by an internal, private CA is supported if the CRL for the internal PKI is publicly available.

Key Type

RSA is the most common key type used for SSL certificates. However, Elliptic Curve Cryptography (ECC) keys offer better security and performance, so it is recommended that the SSTP SSL certificate be created using an ECC key instead.

Always On VPN Certificate Requirements for SSTP

To use an ECC key, be sure to specify the use of a Cryptographic Next Generation (CNG) key and select the ECDSA_P256 Microsoft Software Key Storage Provider (CSP) (or greater) when creating the Certificate Signing Request (CSR) for the SSTP SSL certificate.

Always On VPN Certificate Requirements for SSTP

Most public CAs will support certificate signing using ECC and Elliptic Curve Digital Signature Algorithm (ECDSA). If yours does not, find a better CA. 😉

Forward Secrecy

Forward secrecy (sometimes referred to as perfect forward secrecy, or PFS) ensures that session keys can’t be compromised even if the server’s private key is compromised. Using forward secrecy for SSTP is crucial to ensuring the highest levels of security for VPN connections.

To enforce the use of forward secrecy, the TLS configuration on the VPN server should be prioritized to prefer cipher suites with Elliptic Curve Diffie-Hellman Ephemeral (ECDHE) key exchange.

Authenticated Encryption

Authenticated encryption (AE) and authenticated encryption with associated data (AEAD) is a form of encryption that provides better data protection and integrity compared to older block or stream ciphers such as CBC or RC4.

To enforce the use of authenticated encryption, the TLS configuration on the VPN server should be prioritized to prefer cipher suites that support Galois/Counter Mode (GCM) block ciphers.

Important Note: In Windows Server 2016, GCM ciphers can be used with both RSA and ECC certificates. However, in Windows Server 2012 R2 GCM ciphers can only be used when an ECC certificate is used.

SSL Offload

Offloading SSL to a load balancer or application delivery controller (ADC) can be enabled to improve scalability and performance for SSTP VPN connections. I will cover SSL offload for SSTP in detail in a future post.

Summary

SSTP can provide good security for VPN connections when implementation and security best practices are followed. For optimum security, use an SSL certificate with an EC key and optimize the TLS configuration to use forward secrecy and authenticated cipher suites.

Additional Information

Always On VPN ECDSA SSL Certificate Request for SSTP

Always On VPN and Windows Server Routing and Remote Access Service (RRAS)

Always On VPN Protocol Recommendations for Windows Server RRAS

Always On VPN Certificate Requirements for IKEv2

3 Important Advantages of Always On VPN over DirectAccess

Microsoft SSTP Specification on MSDN

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