Popup Phishing: Online Banking In-Session Phish Need No E-Mail Hook

A new research report shows a new phishing vector -- one that can take place inside supposedly secure banking and other protected session, using a pop-up window rather an e-mail to fool their victims. According to researchers, every browser is vulnerable to the exploit. It's called in-session phishing, and it has the potential to be very troublesome.Researchers at secure transaction protection firm Trusteer have announced a new phishing strategy aimed at customers during secure transactions such as online banking.

This one's particularly nasty for a bunch of reasons.

For one thing, it uses no e-mail to place the hook in in front of the user, dropping in via a popup containing malicious links and requests for information.

For another, even more disturbing reason,the popup appears while the user is actually engaged in an https sessions. The popup, indeed, appears to be from the institution itself, the bank the user is doing business with, for example.

Third, and this one may be the most worrisome of all, no malware resides on the user's computer, meaning that there's nothing there for anti-malware tools to detect. Because the attack comes from outside the secure site via your browser, the site's lock stays locked, the green (or yellow for older browsers) doesn't change, and you have no reason to think that your security's been compromised.

Works like this: the popup phish generator resides on infected Web sites, of which there are plenty. many of them legit. If the user is visiting one of those sites while engaged in a secure transaction, the in-session phish generator takes advantage of a JavaScript function (unspecified by Trusteer) and fashions a popup based on browser information about the institution the user is working with and sends it forth. According to Trusteer, the vulnerability exists in all major browsers.

The result: As most of us have become accustomed to doing, you're banking away, assuming that the https and SSL certificate ensure a private safe, transaction. A popup that appears to be from your bank appears, requesting additional information.

Provide the information, click the link and you've been phished.

So far there's no evidence of this one in the wild, but that's only a matter of time, as with any newly discovered vulnerability.

Some strategies you can practice to protect yourself:

Don't have any other Web pages open while you're performing banking or other secure transactions.

Log out of banking completely before going to any other Web sites.

Never respond to any popup, however legit it looks, while engaged in a secure transaction (or doing anything else, would be my advice.)

As noted, in-session phishing hasn't, well, popped up in the wild, but that hardly means it won't. Pass the word.

Trusteer's In-Session Phishing Advisory can be found here.