Advisory: Remote command execution in planetGallery
An admin of planetGallery is allowed to create new galleries and upload
images. Because of a vulnerable regular expression, he may also upload
PHP scripts and thereby execute arbitrary commands with the privileges
Affected Versions: <= 22.05.2006
Fixed Versions: 14.07.2006
Vulnerability Type: Remote command execution
Vendor-Status: informed, fixed version released
PlanetGallery is a commercial PHP script which is used to publish image
galleries, show image descriptions and send picture postcards generated
from the galleries.
The faulty regular expression is in admin/gallery_admin.php:
193 $allow_file_types = 'gif|jpg|jpeg|png|bmp';
197 if (preg_match('#.'.$allow_file_types.'?#i',
Each variable $_FILES['grafik']['name'][$i] contains the filename of an
uploaded file. Only images with filename extensions supplied in
$allow_file_types are allowed, but the regular expression also matches
files like 'example.png.php'. Webservers interprete this as a PHP script.
Proof of Concept
Create a gallery and upload a PHP script named 'evil.png.php'
containing '<?php phpinfo(); ?>'.
You should see the phpinfo page.
Change line 193 of admin/admin_gallery.php to:
$allow_file_types = '(gif|jpg|jpeg|png|bmp)';
And line 197 to:
Update to the newest version 14.07.2006.
The attacker has to be admin of planetGallery to exploit this
vulnerability. If your admin directory is protected by a .htaccess file
(as the author strictly recommends), the risk is considered low,
otherwise everybody can impersonate the admin and exploit this
vulnerability. PlanetGallery is not a multiuser gallery CMS, so the
admin of planetGallery is probably the maintainer of the website who
will have access to the system anyway. RedTeam therefore rates the risk
of this vulnerability as low.
2006-07-13 Discovery of vulnerability
2006-07-13 Vendor is informed
2006-07-14 Vendor releases fixed version
2006-07-20 Advisory is released
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