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Cross-Site Scripting vulnerability in Tribulant Slideshow Galleries
WordPress Plugin
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Spyros Gasteratos, July 2016

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Abstract
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A Cross-Site Scripting vulnerability was found in the Tribulant
Slideshow Galleries WordPress Plugin. This issue allows an attacker to
perform a wide variety of actions, such as stealing Administrators'
session tokens, or performing arbitrary actions on their behalf. In
order to exploit this issue, the attacker has to lure/force a logged on
WordPress Administrator into opening a malicious website.

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OVE ID
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OVE-20160714-0016

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Tested versions
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This issue was successfully tested on Tribulant Slideshow Galleries [2]
WordPress Plugin version 1.6.3.

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Fix
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A fix for this issue is not available.

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Introduction
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The Tribulant Slideshow Galleries [2] WordPress Plugin allows you to
feature WordPress content in a beautiful and fast JavaScript-powered
slideshow gallery. A Cross-Site Scripting vulnerability has been found
in the Tribulant Slideshow Galleries plugin. This issue allows an
attacker to perform a wide variety of actions, such as stealing
Administrators' session tokens, or performing arbitrary actions on their
behalf. In order to exploit this issue, the attacker has to lure/force a
logged on WordPress Administrator into opening a malicious website.

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Details
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A reflected cross site scripting vulnerability exists in the plugin
Slideshow Galleries. This issue is due to to the fact that the
view/admin/galleries/index.php file uses the following code to output an
HREF link:
"<a href="<?php echo GalleryHtmlHelper::retainquery('orderby=id&order='
.(($orderby == "id") ? $otherorder : "asc")); ?>">"

The above code fails to perform any output encoding on the retainquery
method, thus allowing the tag to be closed and to inject a script
element:
/wp-admin/admin.php?page=slideshow-galleries&method=save"><script>alert(1)<%2fscript>pwned

Please note that this particular method is called another 19 times in
the project. This indicates that more similar vulnerabilities could
exist in the code.

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Proof of concept
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http://<target>/wp-admin/admin.php?page=slideshow-galleries&method=savegtlcq%5C%22%3E%3Cscript%3Ealert%281%29%3C%2Fscript%3Exsxa2

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References
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[1] https://sumofpwn.nl/advisory/2016/cross_site_scripting_vulnerability_in_tribulant_slideshow_galleries_wordpress_plugin.html
[2] https://wordpress.org/plugins/slideshow-gallery/