After all, your bank already knows your confidential information-- why would they contact you to ask about it? If you are worried that a security email or security phone call may be about a real problem -- hang up, or go offline, and call the number on the back of your credit or debit card-- that way, you know you are reaching the bank.
The bad guys use "PH-ony" PHishing emails to take you to a page that may include a frame so the edge of the page actually is your bank's home page-- but the window where you give up your confidential data links to some hacker's computer, possibly in Russia. Neal Walters of the AARP Public Policy Institute has a new factsheet Gone Phishing, latest in his series on id theft and credit reporting issues.