This system will in NO WAY affect your accounts security from outside sources.
*Please note that man in the middle will not work either, no code means no code to steal*
They try to make it easier for you to log in after D/Cing, and you complain.
This change does nothing to stop the MitM attack.
A “Man in the Middle Attack,” is a Trojan that works by blocking your access to the real log in server, and redirecting you to a spoof Log in screen/site. They then harvest all of your log in information, in real time, including your one time use Authenticator code. The hackers then very quickly uses this info to access your in game account, before the Authenticator code expires.
Now if we never have to use our authenticator again from our "Trusted" Computer, them maybe it would protect us from the MitM. However even with this new system we still have to use our authenticators: at least once per week; if we enter the wrong password too many times; And if there is a wide chance in our IP, for any reason.
If we get prompted for our authenticator, we have no way of knowing it is Blizzard doing it, or a hacker with the MitM. Are we suppose to assume each time we are prompted for our authenticator, that it is a MitM attack? If so what are suppose to do them? Wipe our computers, call Blizzard, run around like chickens with our heads cut off? Only for it to turn out to be a periodic check by Blizzard.
In fact this change really weakens your protection, from the MitM. Before they only had a one time limited access to your account. Now the new system adds their computer/location to your "Trusted" list. Therefore they can keep accessing your account as many time as they want without being required to re-authenticate.
The MitM Trojan is no simple keylogger that you can pick up from a day one Flash exploit. It requires YOU to install a very large executable file to work. "Man In the Middle," Attacks were very, very rare. I have been following the CSF almost every day, for over 3 years now, and as far as I know there hasn't been a confirmed case of one in well over all most 2 years. In fact there has only a very small hand full of confirm cases at all. They require a very big hole in your internet security, and very good timing on the hackers part.
The main thing the handful of players that had their accounts hacked had in common were: They all went to a fake/spoof wowmatrix, curse, and other spoofed addon sites, and down loading the spoof site's auto addon updater; They hadn't up dated their Windows fire walls, and or running a bootleg copy of Windows. So if you are careful about the sites you visit, and keep your computer security up dated, including your firewall, there is a low risk that this happened to you.
Frankly if my security habits are so bad and sloppy, that I get hit with a MitM attack, I deserve to be hacked, and never get my account back. In fact having my Blizzard account hack in this manner Would be a Blessing, it would let me know how much my other stuff id a risk. To contact my bank and everyone I pay online, and change all of my accounts.
One more thing about the MitM attack. The Back in October of last year: Blizzard instituted a new security protocol; where if the system senses a change in our access patterns, it will lock you out of your account, until you reset your password. This "Change in Access Pattern" lockout will happen irregardless, if you have an authenticator or not.
It is this change that helps protect you from, or at least slows down the MitM attack, and not the new change to the authenticator system. A lot of people have confused, or do not understand, the 2 different changes, as being one and the same. They are not! They are 2 totally different systems, and occurred several months apart.
Lastly: The "Change in Access Pattern" lockout system does not protect, against a Hacker that uses a spoof IP that is in one of your IP's range. That is why it is wise to have a Authenticator too. However if the Hacker is using a MitM attack, as well as a Spoof IP, they got you.