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Researcher Bypasses Google Password Alert For Second Time
Trailrunner7 writes with this excerpt: A security researcher has developed a method–actually two methods–for defeating the new Chrome Password Alert extension that Google released earlier this week.
The Password Alert extension is designed to warn users when they're about to enter their Google passwords into a fraudulent site. The extension is meant as a defense against phishing attacks, which remain a serious threat to consumers despite more than a decade of research and warnings about the way the attacks work.
Just a day after Google released the extension, Paul Moore, a security consultant in the U.K., developed a method for bypassing the extension. The technique involved using Javascript to look on a given page for the warning screen that Password Alert shows users. The method Moore developed then simply blocks the screen, according to a report on Ars Technica. In an email, Moore said it took him about two minutes to develop that bypass, which Google fixed in short order.
However, Moore then began looking more closely at the code for the extension, and Chrome itself, and discovered another way to get around the extension. He said this one likely will be more difficult to repair.
"The second exploit will prove quite difficult (if not near impossible) to resolve, as it leverages a race condition in Chrome which I doubt any single extension can remedy. The extension works by detecting each key press and comparing it against a stored, hashed version. When you've entered the correct password, Password Alert throws a warning advising the user to change their password," Moore said.
The Password Alert extension is designed to warn users when they're about to enter their Google passwords into a fraudulent site. The extension is meant as a defense against phishing attacks, which remain a serious threat to consumers despite more than a decade of research and warnings about the way the attacks work.
Just a day after Google released the extension, Paul Moore, a security consultant in the U.K., developed a method for bypassing the extension. The technique involved using Javascript to look on a given page for the warning screen that Password Alert shows users. The method Moore developed then simply blocks the screen, according to a report on Ars Technica. In an email, Moore said it took him about two minutes to develop that bypass, which Google fixed in short order.
However, Moore then began looking more closely at the code for the extension, and Chrome itself, and discovered another way to get around the extension. He said this one likely will be more difficult to repair.
"The second exploit will prove quite difficult (if not near impossible) to resolve, as it leverages a race condition in Chrome which I doubt any single extension can remedy. The extension works by detecting each key press and comparing it against a stored, hashed version. When you've entered the correct password, Password Alert throws a warning advising the user to change their password," Moore said.
After reading the summary, I went ahead and downloaded the extension to see if I could figure out a way to bypass it. I tried a few more obvious methods first, all of which were detected by the extension.
My 4th attempt at bypassing the extension seems to work just fine though. It works by binding the window.onkeyup and window.onkeydown methods, determining which character corresponds to the key being pressed, then appending that character to the username or password fields if one of them has focus. Once the value has been added to the appropriate field, the event is cancelled using e.preventDefault(). I put a proof-of-concept up on my site in case anyone is interested. Here's the raw code for that page if you don't want to go to some random SlashDot poster's website.
This method only took a few minutes for me to come up with, so I'm probably not the first one to figure this out, but I thought I'd share anyways.