Moxie Marlinspike calls it in his article http://www.thoughtcrime.org/blog/the-cryptographic-doom-principle/https://moxie.org/2011/12/13/the-cryptographic-doom-principle.html the doom principle:
if you have to perform any cryptographic operation before verifying the MAC on a message you’ve received, it will somehow inevitably lead to doom.
He also demonstrates two attacks which are possible because of trying to decrypt before checking the MAC.
To summarize: "Encrypt Then Authenticate" is the way to go.
