Going to share this news with everyone. Kody over at World of Raids has said it the best so I'm just going to repeat what he's said over there.
Anyone who has an authenticator attached to their account should run a search (and probably an antivirus scan in case it's on the threat list already) immediately and ensure the file emcor.dll does not exist on your computer. This file is one reported to be allowing hackers to access World of Warcraft accounts that have authenticators attached to them. It's also possible there are other variations of these suspicious files, so if anyone has additional information please respond in the comments.
Based on this thread, the file may be found in /users/username/appdata/Temp. Since the file is fairly new (first mentions of it are only a few days ago), and the common source is unknown, I urge everyone to not log in to World of Warcraft or the account management site until you've run a scan. Confirm your computer is secure before using your authenticator, because this DLL file is allowing hackers to crack through it and access your account.
A warning sign that you're currently infected with this keylogger is that WoW will say your authentication code is incorrect, even if you know for sure you typed in the correct code. Thanks to Cameron for posting about this in our forums, too.