Just Another Security/Programming Blog: Paypal Complete 2-Factor Authentication(2FA) Bypass Exploit.

Tuesday, 5 August 2014

Paypal Complete 2-Factor Authentication(2FA) Bypass Exploit.

Update: It has been patched on the 12th of August. "Surprise?"

[Revision; 6th of August, 2014]
To make it clear: The Paypal account you were 'hacking' did NOT have to be affiliated with the eBay account you were using. In my original tests, I had made a new eBay account using a temporary email, and had gotten into my Paypal through the same method.

It works even without an eBay account, actually.



This blog is an excerpt from my blog entry, "Paypal's 2-FActor Authentication(2FA): The Good, The Bad, And The Ugly", in which I detail the use[fulness] of Paypal's 2Factor system.

On the 5th of June, 2014, I found a complete bypass for Paypal's 2FA service, in which anybody would be able to access a Paypal account that has 2FA setup, by only logging in through a "special" Paypal page.

eBay, in conjunction with Paypal, provide a service as to where you can link your eBay account to your Paypal account, and when you sell something on eBay, the fees automatically come out of your Paypal account.

When setting this up, you're (obviously) asked for your Paypal login.

Linking the two accounts

Login Page

When you are redirected to the login page(above), the URL contains "=_integrated-registration". Doing a quick Google search for this shows that it isn't used for anything other than eBay; thus it is setup purely for Paypal&eBay.

Once you're actually logged in, a cookie is set with your details, and you're redirected to a page to confirm the details of the process. And this is where the exploit lays. Now just load http://www.paypal.com/ , and you are logged in, and don't need to re-enter your login.

So, the actual bug itself is that the "=_integrated-registration" function does not check for a 2FA code, despite logging you into Paypal.

You could repeat the process using the same "=_integrated-registration" page unlimited times.

I originally found this on the 5th of June, 2014, and reported it to Paypal the same day.

I have also uploaded a demonstration of it on YouTube.

==Found: 5th June 2014==
==Reported: 5th June 2014==
==Response: 27th June 2014==
==2nd Response: 27th June 2014==
==3rd Response: 4th July 2014==

On the 5th of August, I have decided to release this publicly, because despite two months given, it still hasn't been fixed.

You can try it out, by logging into Paypal here: https://www.paypal.com/cgi-bin/webscr?cmd=_integrated-registration&key=0&stamp=1364194631&data=JGHnP2g2ybqbgKfR7%2B1loOlg24LvI/VppQIqFE8DyTO9hqc1x1pQw42CCLy3EdEogm85LYOTKtU2wYNfjFZvuHSx4PjAHLVtlv6sYdPl2FIBLN7BNr3l%2BPe0WPeDhopUWqhw0PYE9EAyZPkgIZWJgWKGGGNPqdQRjlbNGoCCIox7RLfKmtEDeH8KXEOzZDSmvETO%2B7fkoy06CLe9CkJhE0V8Mh9QN/wNYIF6WMFgHsze7RAS8Qe3j/U9I9zYXDPcfB2L5AVCYI53jcWUOxeKXSlcoV0eIcxkLOkLfmSqnaY9vywEQEhEU2PYoKSqefaZBPFh6Y7kWXVD/7id8PvkrJzKaCUq0nhBRfFGtf1kYrK0ZgX%2Byws4HmiTn4GEL/gaUPtpWviP4BCJmeGOhzQEhbFNYwzuzmOWAaqYfsa62DsAcq3LUy1DyAmBfsLhwzRyzZhKlg1NRz5MxTsuBqlh72W6ytc1gEMwh%2BJtBxZTf7EggIaTRLdpjXMlZmwRjkMH2BjX8P4968XicykzmLhTpqpg507flV%2Belq3QNBd9cAliSskS3n/%2Bd1os7FQBnogr4tZ7srcTkoPM5nezXqz3caE/loqoJnkWvlRYfNJpSSysjQ%2BThTgiwNtk4eh8X2r3LhepLD27KdM7I299%2BnWVF9veVjw625ZT%2B3MyQMiO7FbMJdng5baW%2BZIRFIear2GlEJVXMlftP3ibMJAmzGrnKqB0sPwY3augnaBNnz4u32QAaxg8zhvz5FEaELdpFxJ4ptLdRc2MFUBFkUDm%2B5tlpuNl9JzgKTDQnXzYxX/2KYAznivHTlsCcwH68kL6EqoiGGTsFoLzp8TqnLvizULu6tdfnTAhhxV6kCeRRoyN/a62wahvxDibJgTnTjp4d3/xm4nhkQhQ5/xUgtAN9T1aa7n5PinOWS84AOFR0TB3KpwHsQkoQCGXvzdYZh4wD8ECQzYS9lbpaCLm13GqPGK4xC6K2vat8/gt9uoiJbiy77SK2PcMhcRS3KbK9Z0HtDCl&ev=1.0&locale=en_US

(For the love of security, please make sure the page you go to is https://www.paypal.com/...)
Once you login(don't press return to eBay), go to paypal.com.


Found by Joshua Rogers(@MegaManSec)


  1. This comment has been removed by a blog administrator.

  2. Ebay refuses to accept purchases from buyers who do not have a Paypal account HOT-LINKED to their Ebay account, such as TO BYPASS PAYPAL LOGIN SECURITY.
    I have had to stop buying on ebay.


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