Gmail Checker plus Chrome extension XSS/CSRF II

Thursday, June 17, 2010
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Gmail Checker plus Chrome extension XSS/CSRF II
extension: https://chrome.google.com/extensions/detail/gffjhibehnempbkeheiccaincokdjbfe
advisore:http://lostmon.blogspot.com/2010/06/gmail-checker-plus-chrome-extension.html
Exploit available:yes vendor notify: NO
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So in this case "Google Mail Checker Plus" version 1.1.7 (2010-02-10)
has a flaw that allow attackers to make XSS style attacks.

All extensions runs over his origin and no have way to altered data from extension
or get sensitive data like , email account or password etc..

if we look how many users have instaled this extension =>
https://chrome.google.com/extensions/detail/gffjhibehnempbkeheiccaincokdjbfe
303,711 users have instaled it (WoW)

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explanation
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Google Mail Checker Plus allows users to view wen they have a new mail and
view a preview of the mail ....

If a attacker compose a new mail with html or javascript code in mail
body & send it to victim´s the code is executed wen Victim´s click in the
extension to view a preview of mail.

So for exploit we need to compose a "special" mail
for example if we put directly in the mail body a iframe like
"><iframe src="javascript:alert(location.href);"></iframe>
the extension shows this code in plain text and the alert isn´t executed...
them we need to use a Feature from gmail ( auto conver links in clicable urls)
them we can compose a email body with a http link like
http://"><iframe src="javascript:alert(location.href);"></iframe>
or compose a mail link like :
lalala@"><iframe src="javascript:alert(location.href);"></iframe>.com
in the two cases the alert is executed wen try to preview the email
with the extension :) it is executed in context location.href value is
"about:blank"


Gmail is a safe place , but the extensions to manage it, can be a potential
vector to attack.

For example send a email With a logout acction in gmail in body
http://"><iframe src="https://mail.google.com/mail/?logout&hl=es"></iframe>
it closes the sesion on gmail , this is a CSRF.
also if the user has mark option to show notifications on desktop this issue execute the iframe too in the desktop notifications window and can cause to a denial of service of extension, for example if the victim´s try to change any option in options page from extension :P

So we have dispute it in http://code.google.com/p/chromium/issues/detail?id=45401
The developer has release a patch version in trunk for other issues what i disclose before
see for references for previous vulns => OSVDB ID :65459 and OSVDB ID: 65460
previous patch =>
http://github.com/AndersSahlin/MailCheckerPlus/blob/54ab118e505feae819e676c8e525e8fe5409c981/src/mailaccount.class.js
and see diff => http://github.com/AndersSahlin/MailCheckerPlus/commit/54ab118e505feae819e676c8e525e8fe5409c981#diff-0

I release it as 0-day and no notify to vendor because
in the previous issues , he patch the vulns and don´t
make any reference to it and stealing credits on discover
Them i release this new vulns without notify developer :)


UPDATED :Now the extension in about secition reflects the vulnerability and credit it to me :)



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Thnx for your time !!!

atentamente:
Lostmon (lostmon@gmail.com)
Web-Blog: http://lostmon.blogspot.com/
Google group: http://groups.google.com/group/lostmon (new)
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