How many tabs do you have open in your browser right now? Potentially, some of them can be tabnapped -- taken over by crooks looking to trick you into re-entering your password and user name.Tabnapping -- a phishing attack that takes over an inactive browser tab -- is at the moment more talked about than active. But considering how tricky this attack is, look for it to appear in the wild before long.

As described in Firefox creative lead Aza Raskin's blog, a tabnapping attack takes over an inactive browser tab, alters it to resemble a Gmail log-in page, the attacker betting that when the user returns to that tab the supposition will be that they left Gmail open, will log in again, and -- wham! -- the attacker has the user's password and log-in info.

Incidentally, Raskin's blog entry puts his demo where his post is -- tab away from the entry for five seconds and the page gets replaced with a phony gmail log-in image. The demo -- and the attack -- works on all major browsers, according to Raskin.

Not too hard to see even more malicious uses for the attack. Facebook and other social networking log-in pages; bank and other financial info requests; anything that requires a log-in and password, and can be duplicated/faxed by the phishers.

While the technique itself is tricky enough, what should really have our guards up is the bet the phishers will be making -- that you won't remember whether or not you had a Gmail or banking page open and didn't log in, whether you'll think that you session timed out, and whether you're immediate respose to returning to the now-compromised tab will be to log "back" in without giving the matter any further though.

That sort of immediate response is what phishers have counted on to good effect for years in link-laden e-mails and otehr phishing expeditions. See a link, click a link: that's the bet, and for plenty of unfortunate users it's a good, if crooked, wager.

See a log-in page, log-in? Pass the word that log-ins and passwords should only be entered through fresh, user-initiated pages. And tell them to:

Close those tabs!

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