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Cross-Site Scripting vulnerability in search function Activity Log
WordPress Plugin
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Edwin Molenaar [2], July 2016

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

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OVE ID
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OVE-20160718-0002

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Tested versions
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This issue was successfully tested on Activity Log [3] WordPress Plugin
version 2.3.2.

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Fix
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This issue is fixed in Activity Log version 2.3.3 [4]

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Introduction
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The Activity Log [3] WordPress Plugin helps monitor & log all changes
and activities on a WordPress site. A reflected Cross-Site Scripting
vulnerability exists in the Activity Log WordPress plugin. This
vulnerability allows an attacker to perform any action with the
privileges of the target user.

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Details
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The vulnerability exists in improper filtering of the search input
parameter $search_data in the file
aryo-activity-log/classes/class-aal-activity-log-list-table.php at line
483. The WordPress sanitize_text_field [5] sanitizer is used, but this
still allows us to use spaces, " and () to craft a Cross-Site Scripting
payload.

public function search_box( $text, $input_id ) {
	
	$search_data = isset( $_REQUEST['s'] ) ? sanitize_text_field(
$_REQUEST['s'] ) : '';
	
	$input_id = $input_id . '-search-input';
	?>
	<p class="search-box">
		<label class="screen-reader-text" for="<?php echo $input_id ?>"><?php
echo $text; ?>:</label>
		<input type="search" id="<?php echo $input_id ?>" name="s"
value="<?php echo $search_data; ?>" />
		<?php submit_button( $text, 'button', false, false, array('id' =>
'search-submit') ); ?>
	</p>

When a search on the activity log is preformed, a CSRF token is added to
the URL, however it is not checked. Consequently, it can be exploited by
luring the target user into clicking a specially crafted link or
visiting a malicious website (or advertisement).

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Proof of concept
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http://<target>/wp-admin/admin.php?page=activity_log_page&s=111"+onfocus=alert(document.domain)+"+autofocus="&paged=1
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References
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[1]
https://sumofpwn.nl/advisory/2016/cross_site_scripting_vulnerability_in_search_function_activity_log_wordpress_plugin.html
[2] https://www.linkedin.com/in/edwinmolenaar
[3] https://wordpress.org/plugins/aryo-activity-log/
[4] https://downloads.wordpress.org/plugin/aryo-activity-log.zip
[5]
https://developer.wordpress.org/reference/functions/sanitize_text_field/