TameMyCerts Policy Module - Uwe Gradenegger

Automatically enter DNS names in the Subject Alternate Name (SAN) of issued certificates - with the TameMyCerts Policy Module for Microsoft Active Directory Certificate Services (ADCS)

Google is a major player with the Chromium project and products based on it such as Google Chrome and Microsoft Edge have moved to implement the RFC 2818 and to no longer trust certificates that no longer fulfill the RFC.

For us, the following sentence is of great explosiveness:

If a subjectAltName extension of type dNSName is present, that MUST be used as the identity. Otherwise, the (most specific) Common Name field in the Subject field of the certificate MUST be used. Although the use of the Common Name is existing practice, it is deprecated and Certification Authorities are encouraged to use the dNSName instead
https://tools.ietf.org/html/rfc2818

Change the Subject Alternative Name (SAN) of a certificate before it is issued - but do it securely!

In net circulate unfortunately much at many Instructions (also the big players are not excluded from this, not even Microsoft itself or the Grand Master Komar), which fatally recommend that the flag EDITF_ATTRIBUTESUBJECTALTNAME2 should be set on the certification authority - supposedly to be able to issue certificates with Subject Alternative Name (SAN) extension for manually submitted certificate requests.

Unfortunately, this procedure is not only unnecessary, it also has some unpleasant side effects, which in the worst case can help an attacker to take over the entire Active Directory structure.

A policy module to tame them all: Introducing the TameMyCerts Policy Module for the Microsoft Certification Authority.

As a Certification Authority operator, you are (among other things) responsible for the identification of the enrollees and the confirmation of the requested identities. The fact that this task is carried out conscientiously and without errors is the central cornerstone for the trust that is placed in the Certification Authority. Well-known companies are already failed in this task, even had to file for insolvency as a result of misrepresentations and/or were severely punished by the major players on the market.

In many cases, we as enterprise (Microsoft) PKI operators (regardless of the quality involved) are able to delegate our task of uniquely identifying an enrollee to Active Directory. In many cases, however, we must also instruct our certification authority(ies) to simply issue whatever is requested.

Issue certificates with shortened validity period

Sometimes it is necessary to issue certificates with a shorter validity period than configured in the certificate template. Therefore, you may not want to reconfigure the certificate template right away or create another certificate template.