WordPress Plugin Quiz And Survey Master 4.5.4/4.7.8 - Cross-Site Request Forgery













Software: Quiz And Survey Master (Formerly Quiz Master Next)
Version: 4.5.4,4.7.8
Homepage: https://wordpress.org/plugins/quiz-master-next/
Advisory report: https://security.dxw.com/advisories/csrfstored-xss-in-quiz-and-survey-master-formerly-quiz-master-next-allows-unauthenticated-attackers-to-do-almost-anything-an-admin-can/
CVE: Awaiting assignment
CVSS: 5.8 (Medium; AV:N/AC:M/Au:N/C:P/I:P/A:N)

CSRF/stored XSS in Quiz And Survey Master (Formerly Quiz Master Next) allows unauthenticated attackers to do almost anything an admin can

A CSRF vulnerability allows an unauthenticated attacker to add questions to existing quizzes.
The question_name parameter is put into a manually-constructed JavaScript object and escaped with esc_js() (php/qmn_options_questions_tab.php line 499). If the user (or attacker) creates a new question on a quiz containing “<script>alert(1)</script>” in the question_name field then “question: ‘<script>alert(1)</script>’,” will get output inside the JS object. All good so far.
However, in js/admin_question.js on line 205, we see this line, as part of some JS-generated HTML:
jQuery(\'<textarea/>\').html(questions_list[i].question.replace(/\"/g, \'\"\').replace(/\'/g, \"\'\")).text()+
This looks okay. We’re creating a TEXTAREA element, setting its HTML to the value of the question_name parameter, and extracting the .text() of it. If we did jQuery(‘<textarea/>’).html(‘<script>alert(1)</script>’).text() we would get “alert(1)” as the output.
However, that’s not how inline JavaScript gets parsed. Between a <script> and a </script>, the HTML parser actually parses “<” as “<” not as “<“. So if we do jQuery(‘<textarea/>’).html(‘<script>alert(1)</script>’).text() we get “<script>alert(1)</script>”.
And since “<script>alert(1)</script>” doesn’t appear anywhere in the page, Chrome’s reflected XSS mitigation measures are not activated. Thus the stored XSS attack can be executed immediately.

Proof of concept

Click the submit button on the following page (in a real attack the form can be submitted without user interaction):
<form method=\"POST\" action=\"http://localhost/wp-admin/admin.php?page=mlw_quiz_options&quiz_id=1\">
<input type=\"text\" name=\"question_type\" value=\"0\">
<input type=\"text\" name=\"question_name\" value=\"<script>alert(1)</script>\">
<input type=\"text\" name=\"question_submission\" value=\"new_question\">
<input type=\"text\" name=\"quiz_id\" value=\"1\">
<input type=\"submit\">

Upgrade to version 4.7.9 or later.

Disclosure policy
dxw believes in responsible disclosure. Your attention is drawn to our disclosure policy: https://security.dxw.com/disclosure/

Please contact us on security@dxw.com to acknowledge this report if you received it via a third party (for example, plugins@wordpress.org) as they generally cannot communicate with us on your behalf.

This vulnerability will be published if we do not receive a response to this report with 14 days.


2015-09-14: Discovered
2016-12-07: Reported to vendor via https://quizandsurveymaster.com/contact-us/
2016-12-07: Requested CVE
2016-12-13: Vendor replied
2016-12-14: Vendor reported issue fixed in version 4.7.9
2016-12-15: Advisory published

Discovered by dxw:
Tom Adams
Please visit security.dxw.com for more information.