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Renew the Registration Authority (RA) certificates for the Network Device Enrollment Service (NDES).

Once NDES has been in operation for some time (typically two years), one is faced with the challenge of renewing the Registration Authority (RA) certificates. Unfortunately, this process is not necessarily solved intuitively and is therefore described in more detail in this article.

The Network Device Enrollment Service (NDES) logs the error message "The Network Device Enrollment Service cannot retrieve one of its required certificates (0x80070057). The parameter is incorrect."

Assume the following scenario:

An NDES server is configured on the network.
HTTP error 500 (Internal Server Error) is reported when accessing the NDES application web page (mscep) and the NDES administration web page (certsrv/mscep_admin).
The events no. 2 and 10 stored in the application event log:

The Network Device Enrollment Service cannot be started (0x80070057). The parameter is incorrect.

The Network Device Enrollment Service cannot retrieve one of its required certificates (0x80070057). The parameter is incorrect.

Configuring the Network Device Enrollment Service (NDES) to operate without a password.

There are situations in which you cannot operate NDES with changing passwords. This is usually the case when there is either no management solution for the devices to be managed, or when it cannot handle changing passwords. Some solutions cannot handle a password at all.

In this case, you can configure NDES not to generate or require a password.

Public Key Infrastructures (PKI) basics

A public key infrastructure comprises all components (hardware, software, people and processes) required for the use of digital certificates. A PKI consists of one or more certification authorities (CA). The tasks of a PKI include:

Ensuring the authenticity of keys, i.e. establishing a traceable link between a key and its origin to prevent misuse.
Revocation of certificates, i.e., ensuring that decommissioned or compromised (e.g., stolen) keys can no longer be used.
Guarantee of liability (non-repudiation), i.e., the owner of a key cannot deny that it belongs to him.
Enforcement of policies, i.e. standardized procedures for the use of certificates.

Cryptography basics

The need for the use for cryptography can be summarized under the notion of ensuring secure communication in the presence of untrusted third parties. The goals of cryptography are:

To prevent data from falling into unauthorized hands (To ensure the confidentiality of data).
Find out if data has been modified during transport (Ensure the integrity of the data).
To clearly identify the source of the data (To ensure the authenticity of the data).
Additionally, users or computers can authenticate themselves using cryptography.

Configuring the Network Device Enrollment Service (NDES) to work with a static password.

In this case, you can configure NDES to generate a static password that will not change afterwards.

Creating a virtual smart card in a Hyper-V guest system

For test environments, it is often helpful to be able to work with smartcards. Below is a brief guide on how to set up a virtual smartcard in a Hyper-V guest using a virtualized Trusted Platform Module (TPM).

Domain Controller Certificate Templates and Smartcard Logon

In order for domain controllers to process smart card logins, they need certificates that provide this function.

(Re-)Installing the Microsoft Standard Certificate Templates

There may be cases where it is necessary to install the standard Microsoft certificate templates before installing the first Active Directory integrated certificate authority (Enterprise Certification Authority), or to reinstall the templates, for example because they have been corrupted or otherwise modified.

Editing the NTAuthCertificates object in Active Directory

In the default configuration, all certification authority certificates of Active Directory integrated certification authorities (Enterprise Certification Authority) are located in an object of type CertificationAuthority named NTAuthCertificates within the Configuration Partition of the Active Directory forest.

Attack vector on Active Directory directory service via smartcard logon mechanism

In simple terms, public key cryptography can be reduced to the assumption that the private part of each key pair is known only to its owner.

A certification authority is responsible for the correct identification of users, computers or resources. Its issued certificates are therefore granted a trust status because all participants assume that their private key is known only to it.

If an attacker succeeds in gaining knowledge of a certification authority's private key, or at least Perform signatures using the private key, the integrity of the certification authority is no longer guaranteed.

Basics: Restricting Extended Key Usage (EKU) in Certification Authority Certificates

A useful hardening measure for Certification Authorities is to restrict the Certification Authority certificates so that they are only used for the actually issued extended key usage (Extended Key Usage) becomes familiar.

In the event of a compromise of the certification authority, the damage is then (at least) limited to the defined extended key usages.

The Smart Card Logon Extended Key Usage, which is of interest for many attacks (in conjunction with the certification authority's membership in NTAuthCertificates) would then only be present in the certification authority certificate of the certification authority that actually issues such certificates.

The Network Device Enrollment Service (NDES) logs the error message "The Network Device Enrollment Service cannot create or modify the registry key Software\Microsoft\Cryptography\MSCEP\EncryptedPassword."

Assume the following scenario:

An NDES server is configured on the network.
The NDES server is configured to work with a static password.
When accessing the NDES administration web page (certsrv/mscep_admin), users are repeatedly prompted for authentication despite having correct credentials.
The following event is stored in the application event log:

The Network Device Enrollment Service cannot create or modify the registry key "Software\Microsoft\Cryptography\MSCEP\EncryptedPassword". Grant Read and Write permissions on the registry key "Software\Microsoft\Cryptography\MSCEP" to the account that the Network Device Enrollment Service is running as.

The Network Device Enrollment Service (NDES) administration web page (certsrv/mscep_admin) reports "You do not have sufficient permission to enroll with SCEP. Please contact your system administrator."

Assume the following scenario:

An NDES server is configured on the network.
When calling the administration web page (certsrv/mscep_admin) the following message appears:

You do not have sufficient permission to enroll with SCEP. Please contact your system administrator.

When calling the Network Device Enrollment Service (NDES) administration web page (certsrv/mscep_admin), one is always prompted to log in.

Assume the following scenario:

An NDES server is configured on the network.
The NDES server is called under a DNS alias.
Despite entering the correct login data, you are always prompted to log in again when you access the NDES administration web page (certsrv/mscep_admin).