Bolt 2.2.4: Code Execution
Security Advisory – Curesec Research Team

1. Introduction

Affected Product:   Bolt 2.2.4  
Fixed in:   2.2.5
Fixed Version Link:   http://bolt.cm/distribution/archive/bolt-2.2.5.zip  
Vendor Contact:   Website: https://bolt.cm  
Vulnerability Type:   Code Execution  
Remote Exploitable:   Yes  
Reported to vendor:   07/14/2015  
Disclosed to public:   08/17/2015  
Release mode:   Coordinated release  
CVE:   n/a  
Google Dork:   "This website is Built with Bolt" (About 11,100 results)  
Credits   Tim Coen of Curesec GmbH  

2. Vulnerability Description

The Bolt CMS does not allow the upload or editing of PHP files in its
admin area, which should prevent code execution once an attacker gained
admin credentials.

However, when uploading, the actual file type is not checked. The theme
editor allows for the renaming of uploaded files, and it does not check
the file extension or file type when doing so. Because of this, an
attacker can gain code execution.

Please note that admin credentials are required.

3. Proof of Concept

    Visit theme editor:
http://localhost/bolt-git-2015-06-25-05c29bf/bolt/files/theme/base-2014
    Upload or edit any existing file with allowed extension to contain
<?php passthru($_GET['e']);
    Rename the file, giving it an extension that will make it
executable, eg .php

The file will not be shown in the theme editor anymore, because PHP
files are not shown, but it will be accessible via eg
http://localhost/bolt-git-2015-06-25-05c29bf/theme/base-2014/README.php

4. Solution

To mitigate this issue please upgrade at least to version 2.2.5:

http://bolt.cm/distribution/archive/bolt-2.2.5.zip

Please note that a newer version might already be available.

5. Report Timeline

07/14/2015   Informed Vendor about Issue
07/24/2015   Vendor releases Version 4.2.3
08/17/2015   Disclosed to public

6. Blog Reference:
http://blog.curesec.com/article/blog/Bolt-224-Code-Execution-44.html