XSS and Uncontrolled redirect Vulns in Encrypted Blog Plugin for Wordpress

# Date: 28 August 2013
# Author: k3170makan
# Vendor or Software Link: http://wordpress.org/plugins/encrypted-blog/
# Version: 0.0.6.2
# Category: webapps
# Tested on: N/A

The Encrypted Blog Plug-in for Wordpress suffers from multiple vulnerabilities exposing authenticated wordpress users to Cross Site Scripting attacks and Uncontrolled redirects and via a combination of these vulnerabilities a leakage of the Encryption key set by the wordpress user for this plugin.

Cross Site Scripting:

The contents of the redirect_to field in the encrypt_blog_form.php, which is supplied via GET method is not sanitized and allows attackers to submit malicious HTML/JavaScript and other client side browser scripting content.

Here's the code:

13 <form name="loginform" id="loginform" action="<?php

14 if( isset( $_GET['redirect_to'] ) && !empty( $_GET['redirect_to'] ) )

15 {

16 echo $_GET['redirect_to'];

17 if( strpos( $_GET['redirect_to'], '?' ) === 

false && substr( $_GET['page'], -1 ) !== '/') {

18 echo '/';

19 }

20 }

21 else

22 {

23 echo './';

24 }

line 16 shows that the echo is done without parsing the redirect_to field's value or remove any potentially malicious HMTL/JavaScript.

PoC:

http://imgur.com/S9L4FeV

Uncontrolled Redirect:

The uncontrolled redirect stems the following code:https://github.com/marcusds/EncryptedBlog/blob/master/encrypted_blog_form.php#L43

line 43 shows that unsanitized and uncontrolled data from the redirect_to field is used to build redirects, meaning that attackers will be able to redirect victims to arbitrary domains.

PoC:

http://imgur.com/LrWmB77