Uwe Gradenegger - Page 16 - Uwe Gradenegger

Requesting certificates via Enroll on Behalf of (EOBO) is not possible because the certificate template is not displayed. The error message is "The certificate template requires too many RA signatures."

Assume the following scenario:

A certificate is requested for a user or a computer from a certificate authority via the certificate management console (certlm.msc or certmgr.msc).
One uses here the Enroll on Behalf of (EOBO) Mechanism.
The desired certificate template is not displayed.
If you check the "Show all templates" checkbox, the following error message will be displayed for the desired certificate template:

The certificate template requires too many RA signatures. Only one RA signature is allowed. Multiple request agent signatures are not permitted on a certificate request.

Basics: Path Length Constraint

The attack on the MD5 signature algorithm demonstrated in late 2008 could only be used to create a usable forged certification authority certificate because the attacked certification authority had not configured any path length restriction.

The limitation of the path length is defined in the RFC 5280 described. The idea behind this is that the maximum depth of the certification authority hierarchy is stored in the "Basic Constraints" extension of a certification authority certificate.

Create an exit module for the certification authority in C#

The Microsoft Certification Authority offers the possibility to create your own Policy and exit modules to develop to extend the functionality of the Certification Authority.

Below are the steps necessary to create an exit module in C# using Visual Studio 2019. The exit module will write issued certificates to a configurable directory in the file system.

Configuring the Trusted Platform Module (TPM) Key Attestation

Since Windows 8 it is possible, that private keys for certificates are protected with a - if available - Trusted Platform Module (TPM). This makes the key non-exportable - even with tools like mimikatz.

However, it is not obvious at first glance that it cannot be guaranteed that a TPM is really used. Although no application via Microsoft Management Console or AutoEnrollment possible if the computer does not have a TPM.

However, the configuration in the certificate template is only a default setting for the client. The certification authority will, when requesting do not explicitly check whether a Trusted Platform Module was really used.

To ensure that the private key of a certificate request has really been protected with a Trusted Platform Module, only the TPM Key Attestation remains.

Manually requesting a web server certificate

There are cases in which you cannot or do not want to obtain web server certificates directly from a certification authority in your own Active Directory forest via the Microsoft Management Console, for example if the system in question is not a domain member.

In this case, the use of certificate templates is not possible, and one must manually create a Certificate Signing Request (CSR).

Details of the event with ID 4 of the source Microsoft-Windows-CertificateServicesClient-CertEnroll

Event Source:	Microsoft-Windows-CertificateServicesClient-CertEnroll
Event ID:	4 (0x425A0004)
Event log:	Application
Event type:	Information
Event text (English):	Certificate enrollment for %1 could not access local resources or retrieve %2 certificate template information (%3). Enrollment was not performed.
Event text (German):	Certificate enrollment for %1 could not access local resources or retrieve certificate template information for %2 (%3). No registration is performed.

Details of the event with ID 13 of the source Microsoft-Windows-CertificateServicesClient-CertEnroll

Event Source:	Microsoft-Windows-CertificateServicesClient-CertEnroll
Event ID:	13 (0xC25A000D)
Event log:	Application
Event type:	Error
Event text (English):	Certificate enrollment for %1 failed to enroll for a %2 certificate with request ID %4 from %3 (%5).
Event text (German):	The certificate enrollment for %1 failed to enroll for a certificate %2 with request ID %4 of %3 (%5).

Details of the event with ID 57 of the source Microsoft-Windows-CertificateServicesClient-CertEnroll

Event Source:	Microsoft-Windows-CertificateServicesClient-CertEnroll
Event ID:	57 (0x825A0039)
Event log:	Application
Event type:	Information, Warning and Error
Event text (English):	The "%2" provider was not loaded because initialization failed.
Event text (German):	The "%2" provider was not loaded due to an initialization error.

Details of the event with ID 82 of the source Microsoft-Windows-CertificateServicesClient-CertEnroll

Event Source:	Microsoft-Windows-CertificateServicesClient-CertEnroll
Event ID:	82 (0x825A0052)
Event log:	Application
Event type:	Warning
Event text (English):	Certificate enrollment for %1 failed in authentication to all urls for enrollment server associated with policy id: %2 (%4). Failed to enroll for template: %3
Event text (German):	Certificate registration error for %1 when authenticating for all URLs for the registration server associated with the following policy ID: %2 (%4). Error registering for template: %3

Certificate request fails with error message "A certificate issued by the certification authority cannot be installed. Cannot find object or property. 0x80092004 (-2146885628 CRYPT_E_NOT_FOUND)"

Assume the following scenario:

A certificate is requested from a certification authority.
The certificate is successfully issued by the Certification Authority.
However, when installing the certificate on the target system, the following error message occurs:

A certificate issued by the certification authority cannot be installed. Contact your administrator.
Cannot find object or property. 0x80092004 (-2146885628 CRYPT_E_NOT_FOUND)

Requesting a certificate protected by a Trusted Platform Module (TPM) - without owning a TPM

However, the configuration in the certificate template is merely a default setting for the client. The certification authority will not explicitly check whether a trusted platform module has actually been used when a request is made.

Thus - if the certificate request is done away from the MMC - arbitrary parameters can be used for the private key.

Requesting a certificate is not possible because the certificate template is not displayed. The error message is "Can not find a valid CSP in the local machine."

Assume the following scenario:

A certificate is requested for a user or a computer from a certificate authority via the certificate management console (certlm.msc or certmgr.msc).
Autoenrollment does not request a certificate from the desired certificate template, although it is enabled and the permissions are set accordingly.
The desired certificate template is not displayed when applying manually via the Microsoft Management Console (MMC). If the "Show all templates" check box is selected, the following error message is displayed for the desired certificate template:

Cannot find object or property.
Can not find a valid CSP in the local machine.

Configure a certificate template to use the Microsoft Platform Crypto Provider to enable private key protection through a Trusted Platform Module (TPM).

Since Windows 8, it has been possible for private keys for certificates to be protected with a - if available - Trusted Platform Module (TPM). This ensures that the key is truly non-exportable.

The process for setting up a certificate template that uses a Trusted Platform module is described below.

Requesting a Trusted Platform Module (TPM) protected certificate fails with error message "The requested operation is not supported. 0x80090029 (-2146893783 NTE_NOT_SUPPORTED)"

Assume the following scenario:

A certificate template is configured to use the Microsoft Platform Crypto Provider, so the private key generated when the certificate is requested is protected with a Trusted Platform Module (TPM).
However, certificate request fails with the following error message:

An error occurred while enrolling for a certificate.
A certificate request could not be created.
Url: CA02.intra.adcslabor.de\ADCS Lab Issuing CA 1
Error: The requested operation is not supported. 0x80090029 (-2146893783 NTE_NOT_SUPPORTED)

Google Chrome and Microsoft Edge do not check certificate revocation state

More and more companies are using the Google Chrome browser or the new Chromium-based Microsoft Edge (codename Anaheim) on.

When distributing one of these two browsers, it should be noted that they sometimes behave differently from other browsers in terms of certificates.

Besides the fact that Chromium, unlike Internet Explorer and the previous Edge (codename Spartan) the RFC 2818 enforces, it also behaves in the Checking blocking information different.