Fake In Game Whisper?

Did the whisper encourage you to visit an external website, Darkfen? One which asked you to input specific account information?

If so, I've the following advice for you (which I provided earlier to a player in a similar position):

Q u o t e:
If you still have access to the chat line in-game, Penyapu, right-click on the line and report it as spam. This will alert our Game Master staff appropriately to the malicious advertisement.

If you have since logged out of the game and are unable to use the right-click, "Report as Spam" option, go ahead an open an in-game petition. Include the author's name (note: in this case, the name uses an "í" instead of an "i") and realm, as well as a brief description of the message. You're welcome to type out the character name in-full, using the alt code 161 to recreate the high-ASCII letter, or simply note that the "i" in "Blizzard" is high-ASCII.

You're also welcome to report the website you visited directly to our Hacks team for further review. To do so, visit the following web form:

http://us.blizzard.com/support/webform.xml

Select "World of Warcraft" and then "Hacks, Cheats, and Exploits" from each respective drop-down box. From there, select "Website that scams users" from the third drop-down and complete the requested information fields as they appear.

Lastly, here are some tips for securing your computer and account:

1) Complete any operating system updates.
2) Run a full security scan of your computer to check for possible malware.
a) For software recommendations, please check out this thread: http://forums.worldofwarcraft.com/thread.html?topicId=1778038509&sid=1

3) Once this scan is complete, or from a computer you know to be clean, set up and register a new email address. Ensure that the username and password for this new address do not sync up with your WoW account name or any previous passwords; also ensure that they do not sync up with any usernames or passwords for other log types (previous email addresses, MySpace, Facebook, etc).
4) Update your password after.
5) Consider updating your physical address within Account Management once your new email is registered and confirmed. Only do this if your secondary address is both accurate and valid for you, though; do not provide false information.
6) Look into the purchase of a Blizzard Authenticator, or (if you've a Battle.net account), a Mobile Authenticator
a) Information about Authenticator services may be found here: http://us.blizzard.com/support/article.xml?articleId=24986
b) Information regarding Battle.net accounts may be found here: http://forums.worldofwarcraft.com/thread.html?topicId=15864847501&sid=1

Let me know if you've any further questions!

If you can provide me the name and realm of the character on which this whisper was received, I can confirm whether or not the message was malicious in nature. :)

Q u o t e:
It sent me to a web site that looked like wow and I change my log in clue. I have since changed my password. will I be ok?

Go ahead and follow those steps I noted above, Darkfen. They should help bolster your account's security considerably. :)

Q u o t e:
Actually if you call and report that you were hacked one of the things they do after confirming you are you and not the hacker is have you change you secret question & answer.

I only know this as a friend was hacked last week and told me that one of the things they had him do was changed his Q&A.

Your friend may have merged into a Battle.net account and that gives him an opportunity to pick a new one - but the current one cannot be changed.