[FD] [CVE-2018-6194, CVE-2018-6195] PHP Object Injection + XSS in WordPress Splashing Images Plugin

[<nicolas.buzy-debat@xxxxxxxxxx>]

Product: WordPress Splashing Images Plugin - 
https://wordpress.org/plugins/wp-splashing-images/
Vendor: Studio Espresso
Tested version: 2.1


** CVE ID: CVE-2018-6194 **

:: CVE description ::
A cross-site scripting (XSS) vulnerability in 
admin/partials/wp-splashing-admin-sidebar.php in the wp-splashing-images plugin 
before 2.1.1 for WordPress allows remote attackers to inject arbitrary web 
script or HTML via the search parameter to wp-admin/upload.php.

:: Technical details ::
In wp-splashing-images/admin/partials/wp-splashing-admin-sidebar.php:9, the 
search HTTP GET parameter is directly echoed into the value attribute of an 
HTML form field without proper sanitization. An attacker can close the HTML 
input tag with the "> expression and inject arbitrary HTML/JavaScript code.

Vulnerable code:

<input type="search" id="post-search-input-splashing" name="search" 
value="<?php echo $_GET['search']; ?>" placeholder="<?php _e('Search 
unsplash.com', 'wp-splashing-images'); ?>">

https://plugins.trac.wordpress.org/browser/wp-splashing-images/trunk/admin/partials/wp-splashing-admin-sidebar.php?rev=1675965#L9

:: Proof of Concept ::
http://<host>/wp-admin/upload.php?page=wp-splashing&search="><script>alert(document.cookie);</script>


** CVE ID: CVE-2018-6195 **

:: CVE description ::
admin/partials/wp-splashing-admin-main.php in the wp-splashing-images plugin 
before 2.1.1 for WordPress allows authenticated (administrator, editor, or 
author) remote attackers to conduct PHP Object Injection attacks via crafted 
serialized data in the 'session' HTTP GET parameter to wp-admin/upload.php.

:: Technical details ::
In wp-splashing-images/admin/partials/wp-splashing-admin-main.php:23, the 
contents of the session HTTP GET parameter is base64-decoded and then 
unserialized.

Vulnerable code:

<?php if($_GET['session']) {
$data = unserialize(base64_decode($_GET['session']));
 
https://plugins.trac.wordpress.org/browser/wp-splashing-images/trunk/admin/partials/wp-splashing-admin-main.php?rev=1675965#L23

By carefully crafting a URL, a remote and authenticated (administrator, editor 
or author) attacker can inject a base64-encoded serialized PHP object into the 
current WordPress instance. Depending on the available classes within the 
current context and on what actions are performed within their relevant magic 
methods (such as __wakeup() or __destruct() ), impacts can go from arbitrary 
file deletion to arbitrary code execution.

:: Proof of Concept ::
Using pluginvulnerabilities.com's plugin [1], we can easily check that this 
vulnerability is exploitable:
http://<host>/wp-admin/upload.php?page=wp-splashing&session=TzoyMDoiUEhQX09iamVjdF9JbmplY3Rpb24iOjA6e30%3D

[1] 
https://www.pluginvulnerabilities.com/2017/07/24/wordpress-plugin-for-use-in-testing-for-php-object-injection/


** Solution **
Update to version 2.1.1


** Timeline **
10/01/2018: vendor contacted; vendor gives the e-mail address to send the 
report to
12/01/2018: report sent to vendor
22/01/2018: requested an update regarding the release date of the fix; vendor 
releases the fix on that day
26/01/2018: report published


** Credits **
Vulnerabilities discovered by Nicolas Buzy-Debat working at Orange Cyberdefense 
Singapore (CERT-LEXSI).

--
Best Regards,

Nicolas Buzy-Debat
Orange Cyberdefense Singapore (CERT-LEXSI)
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