Why is subject verification an effective means to detect MitM attacks in TLS? [duplicate]

Question

Say, an attacker fakes an original server certificate by a trusted CA using a another certificate from the same CA in a Man-in-the-middle attack. Why can this be detected using subject verification on the client-side?

(I'm not asking about the general workings of the protocol, all it's mechanisms, but, in the framework of those mechanisms, and assuming a general knowledge of TLS, how subject verification specifically prevents a MitM attack, without the need to explain extraneous mechanics of TLS.)

Answer 1

Here is my attempt to answer the question, based on my research in the meantime.

The attacker may obtain another certificate from a trusted CA, but he is unable to alter this certificate in any way. The assumption is that the CA will not issue a certificate for the subject under attack to the attacker, since he cannot prove that he owns the subject (domain name).

When the attacker tries to mediate the traffic between the client and server in a MitM attack, he has to present his own certificate to the client, instead of the servers, to be able to eavesdrop on the traffic. If the client performs subject verification, he will see that the attackers certificate does not contain the correct subject, even though his certificate is coming from a trusted CA. This way subject verification can detect MitM attacks.