We are using an internal Certificate Authority for our company. We noticed that it is possible to add as subjectAltName the hostname without the domain. We are using example.org for internal servers and example.com for external, public facing servers.
E.g. instead of using mysite.example.org, we can create a certificate like:
In this way people can use https://mysite/ and it will work. The DNS search is example.org and example.com.
I have 3 questions:
- is it secure?
- what are the security problems that could be cause by such setup?
- what is the type of attack that someone could take advantage of this config.
Edit1: It seems that public certificate authorities are moving away from signing certificates using an "internal name": https://cabforum.org/internal-names/ and https://www.digicert.com/internal-names.htm