Date: Tue, 05 Aug 2014 01:15:45 +1000
From: Joshua Rogers <megamansec@...il.com>
To: fulldisclosure@...lists.org
Subject: [FD] Paypal Complete 2-Factor Authentication(2FA) Bypass Exploit.
 Working as of August 5th, 2014.

Today, the 5th of August, I release my Paypal 2FA bypass exploit.
It's been exactly 2 months since I've reported this bug, and due to the
simplicity of it, I believe I've given Paypal long enough to fix it.

It's still not fixed.


Full blog can be found here: http://blog.internot.info/
My website: http://internot.info/
My Twitter: https://www.twitter.com/MegaManSec


*This blog is an excerpt from my blog entry, "Paypal's 2-FActor
Authentication(2FA): The Good, The Bad, And The Ugly
<http://blog.internot.info/2014/06/paypals-2-factor-authentication2fa-good.html>",
in which I detail the use 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.



<http://1.bp.blogspot.com/-uxvDxHa7Yq8/U5OdMPXKGqI/AAAAAAAAAJE/j5-j7fZULTc/s1600/Screenshot+from+2014-06-06+21:05:01.png>

Linking the two accounts






<http://1.bp.blogspot.com/-8nyKzVWa4IY/U5Odaf0MHeI/AAAAAAAAAJM/0B1xGx7l6gk/s1600/Screenshot+from+2014-06-06+21:06:23.png>

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.




<http://3.bp.blogspot.com/-fmOAdRhEkzU/U5OdjPA2GkI/AAAAAAAAAJU/pn4DoliZPhY/s1600/Screenshot+from+2014-06-06+21:07:18.png>



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&amp;key=0&amp;stamp=1364194631&amp;data=JGHnP2g2ybqbgKfR7%2B1loOlg24LvI/VppQIqFE8DyTO9hqc1x1pQw42CCLy3EdEogm85LYOTKtU2wYNfjFZvuHSx4PjAHLVtlv6sYdPl2FIBLN7BNr3l%2BPe0WPeDhopUWqhw0PYE9EAyZPkgIZWJgWKGGGNPqdQRjlbNGoCCIox7RLfKmtEDeH8KXEOzZDSmvETO%2B7fkoy06CLe9CkJhE0V8Mh9QN/wNYIF6WMFgHsze7RAS8Qe3j/U9I9zYXDPcfB2L5AVCYI53jcWUOxeKXSlcoV0eIcxkLOkLfmSqnaY9vywEQEhEU2PYoKSqefaZBPFh6Y7kWXVD/7id8PvkrJzKaCUq0nhBRfFGtf1kYrK0ZgX%2Byws4HmiTn4GEL/gaUPtpWviP4BCJmeGOhzQEhbFNYwzuzmOWAaqYfsa62DsAcq3LUy1DyAmBfsLhwzRyzZhKlg1NRz5MxTsuBqlh72W6ytc1gEMwh%2BJtBxZTf7EggIaTRLdpjXMlZmwRjkMH2BjX8P4968XicykzmLhTpqpg507flV%2Belq3QNBd9cAliSskS3n/%2Bd1os7FQBnogr4tZ7srcTkoPM5nezXqz3caE/loqoJnkWvlRYfNJpSSysjQ%2BThTgiwNtk4eh8X2r3LhepLD27KdM7I299%2BnWVF9veVjw625ZT%2B3MyQMiO7FbMJdng5baW%2BZIRFIear2GlEJVXMlftP3ibMJAmzGrnKqB0sPwY3augnaBNnz4u32QAaxg8zhvz5FEaELdpFxJ4ptLdRc2MFUBFkUDm%2B5tlpuNl9JzgKTDQnXzYxX/2KYAznivHTlsCcwH68kL6EqoiGGTsFoLzp8TqnLvizULu6tdfnTA
 hhxV6kCeRRoyN/a62wahvxDibJgTnTjp4d3/xm4nhkQhQ5/xUgtAN9T1aa7n5PinOWS84AOFR0TB3KpwHsQkoQCGXvzdYZh4wD8ECQzYS9lbpaCLm13GqPGK4xC6K2vat8/gt9uoiJbiy77SK2PcMhcRS3KbK9Z0HtDCl&amp;ev=1.0&amp;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. 

 

 


---------------


[Thanks to Tim Messerschmidt <https://twitter.com/SeraAndroid> for
escalating the bug for me internally.]



Found by Joshua Rogers(@MegaManSec <https://twitter.com/MegaManSec>)

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