4images 1.7.12: XSS

Date: 2015-12-02 16:26:27

Security Advisory – Curesec Research Team

1. Introduction

Affected Product:	4images 1.7.12
Fixed in:	1.7.13 (update)
Fixed Version Link:	http://www.4homepages.de/download-4images
Vendor Website:	http://www.4homepages.de/
Vulnerability Type:	XSS
Remote Exploitable:	Yes
Reported to vendor:	09/29/2015
Disclosed to public:	12/02/2015
Release mode:	Coordinated release
CVE:	Requested, but not assigned
Credits	Tim Coen of Curesec GmbH

2. Overview

There are two reflected XSS vulnerabilities in 4images, as well as a persistent Open Redirect, which may also lead to XSS in older browsers.

This allows an attacker to execute arbitrary JavaScript in the context of the browser of a victim if the victim clicks on an attacker supplied link or visits an attacker controlled website. With this, it is possible to bypass CSRF protection and thus do anything the victim can do, inject a JavaScript keylogger, or perform phishing attacks.

It should be noted that the XSS vulnerability still existed in another form in the first release of version 1.17.13 and has been fixed with an update to that version.

3. Reflected XSS 1

CVSS

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

Description

When displaying the form to add new images, $_SERVER['PHP_SELF'] is echoed unencoded inside a select tag. Because of this, additional attributes can be added and new HTML tags can be created, leading to XSS.

Proof of Concept

Prior to Version 1.7.12:

http://localhost/4images/admin/images.php/" onfocus=alert(1) autofocus foo="?action=addimages

Version 1.7.13 (before update):

http://localhost/4images/admin/images.php/');alert(1);window.location=('?action=addimages

This required a click of the victim to trigger, and a redirect will be performed after the execution of the injected code.

Code

/admin/images.php show_num_select_row(" ", "num_newimages", $lang['num_addnewimages_desc']); /admin/admin_functions.php function show_num_select_row($title, $option, $desc = "") { global $site_sess, $PHP_SELF, $action, $$option; echo "<tr class=\"".get_row_bg()."\">\n<td><p>".$title."</p></td>\n"; echo "<td align=\"right\"><p>".$desc; $url = $PHP_SELF; $url .= preg_match("/\?/", $url) ? "&" : "?"; $url .= "action=".$action; $url = $site_sess->url($url); echo "<select name=\"num\" onchange=\"window.location=('".$url."&"; echo $option."='+this.options[this.selectedIndex].value)\">\n"; for ($i = 1; $i < 11; $i++) { echo "<option value=\"$i\""; if ($i == ${$option}) { echo " selected"; } echo ">".$i."</option>\n"; } echo "</select></p></td>\n</tr>\n"; }

4. Reflected XSS 2

CVSS

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

Description

User input is echoed inside the src attribute of a frame, which makes it possible to execute javascript.

Proof of Concept

http://localhost/4images/admin/index.php?goto=javascript:alert%281%29

Code

/admin/index.php if ($action == "") { $action = "frames"; } if ($action == "frames") { if ($goto != "" && strpos($goto, '://') === false) { $framesrc = $site_sess->url($goto); } else { $framesrc = $site_sess->url("home.php"); } ?> <html dir="<?php echo $lang['direction']; ?>"> <head> <title><?php echo $config['site_name']; ?> Control Panel</title> <meta http-equiv="Content-Type" content="text/html; charset=<?php echo $lang['charset']; ?>"> </head> <frameset rows="70,*" framespacing="0" border="0" frameborder="0" frameborder="no" border="0"> <frame src="<?php echo $site_sess->url("index.php?action=head"); ?>" name="head" scrolling="NO" NORESIZE frameborder="0" marginwidth="0" marginheight="0" border="no"> <frameset cols="216,*" framespacing="0" border="0" frameborder="0" frameborder="no" border="0"> <frame src="<?php echo $site_sess->url("index.php?action=nav"); ?>" name="nav" scrolling="auto" NORESIZE frameborder="0" marginwidth="0" marginheight="0" border="no"> <frame src="<?php echo $framesrc ?>" name="main" scrolling="auto" NORESIZE frameborder="0" marginwidth="20" marginheight="20" border="no"> </frameset> </frameset> </html>

5. Persistent Open Redirect

CVSS

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

Description

When showing an uploaded image, the description and keyword are not properly encoded. Tags are removed, but it is still possible to add further attributes to the meta tag they are inserted into.

This makes it possible to inject a redirect. This redirect will be persistent, meaning anyone visiting the site of the uploaded image will be redirected to an attacker controlled website.

The attacker needs the rights to upload images to perform the attack, which means that a category needs to exist where anyone can upload images, or a category needs to exist where registered users can upload images and the registration must be open - which it is by default.

Proof of Concept

Upload an image, as description or keyword use:

Version 1.7.11 and earlier: 5;URL=http://google.com/" http-equiv="refresh" foo=" Version 1.7.12: 5;URL=http://google.com/" http-equiv=refresh foo="

When visiting the page of the uploaded image, a redirect will be performed.

With older browsers, it will be possible to inject and execute javascript as well.

Code

details.php $meta_keywords = !empty($image_row['image_keywords']) ? strip_tags(implode(", ", explode(",", $image_row['image_keywords']))) : ""; $meta_description = !empty($image_row['image_description']) ? strip_tags($image_row['image_description']) . ". " : ""; $site_template->register_vars(array( "detail_meta_description" => $meta_description, "detail_meta_keywords" => $meta_keywords, "prepend_head_title" => $image_name . " - ", ));

6. Solution

To mitigate this issue please upgrade at least to version 1.7.13:

http://www.4homepages.de/download-4images

Please note that a newer version might already be available.

7. Report Timeline

09/29/2015	Informed Vendor about Issue
10/21/2015	Reminded Vendor of Disclosure Date
11/03/2015	Vendor releases new version (1.7.12), partially fixing issues
11/17/2015	CVE Requested (no reply)
11/18/2015	Vendor releases new version (1.7.13), partially fixing issues
11/23/2015	Vendor releases update to version 1.7.13, fixing the issues
12/02/2015	Disclosed to public