Officially the AH is "down for maintenance" on those realms affected, and Blizzard GMs have been telling users to add SMS Protect to their accounts. Just another day in Azeroth.
The usual advice applies: use an authenticator, unique password and be wary of keyloggers. The Mobile Armory is meant to help players on the go manage auctions.
It's a great tool of convenience if you've got some hot items you want to bid on, but of course it also means some cabal of digital thieves has just another way to pinch your shiny golds. Through reports on the, some players have already lost hundreds of thousands in gold transactions.
Probably best you stick with actually standing in the auction house for all your shopping needs.
Report: Blizzard's Mobile Armory hacked, Auction House "down for maintenance"
24 June 2013 | By Simon Priest