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Cross-Site Scripting vulnerability in search function Activity Log
WordPress Plugin
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Edwin Molenaar, 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 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

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Details
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https://sumofpwn.nl/advisory/2016/cross_site_scripting_vulnerability_in_search_function_activity_log_wordpress_plugin.html

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 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).
Proof of concept

https://<target>/wp-admin/admin.php?page=activity_log_page&s=111"+onfocus=alert(document.domain)+"+autofocus="&paged=1


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Summer of Pwnage (https://sumofpwn.nl) is a Dutch community project. Its
goal is to contribute to the security of popular, widely used OSS
projects in a fun and educational way.