Arbitrary File Upload/Execution in Collabtive
- From: Mark Hoopes <xync@xxxxxxxx>
- Date: Mon, 04 Jun 2012 23:07:44 -0400
TITLE: Arbitrary File Upload/Execution in Collabtive
PRODUCT: Collabtive Web-Based Project Management Software (http://collabtive.o-dyn.de/)
VERSIONS: 0.7.5, 0.6.1 confirmed. All versions <= 0.7.5 probable
RESEARCHER: Mark Hoopes (xync@xxxxxxxx/)
ADDITIONAL INFORMATION: http://xync.org/2012/06/04/Arbitrary-File-Upload-in-Collabtive.html
During the upload of an avatar image for a Collabtive user, the manageuser.php script checks the file type using the MIME type provided in the POST request (via the $_FILES['userfile']['type'] variable) rather than by extension. This MIME type can be spoofed via an intercepting proxy or custom POST script allowing a malicious user to upload an arbitrary file. This file will be placed in a predictable web accessible path with an easily determined name. In most installations, execution from this directory is not restricted which allows a remote attacker to execute a PHP script uploaded this way with the privileges of the web user.
Access to the avatar upload function is restricted to logged in users, but because of Collabtive's design decisions in implementing OpenID support, this is easily accomplished. If an unknown user supplies a valid OpenID v1.0 URL as the username on the login page, Collabtive will automatically create a new user based on the referenced credentials. That new user is not authorized to access any projects, but is authorized to upload an avatar image. This allows an attacker with no other knowledge of the host site or its users to exploit the vulnerability.
Upgrade to Collabtive v0.7.6 or greater
Disable script execution of the upload directory via .htaccess for Apache or similar web servers. This should apply at minimum to the /files/[template]/avatar directory but can safely be applied to the entire /files directory.
Sample contents of the .htaccess file are:
AddHandler cgi-script .php .php3 .php4 .phtml .pl .py .jsp .asp .htm .shtml .sh .cgi
Note 'AllowOverride Options AddHandler' or 'AllowOverride All' must be enabled in the main httpd.conf file for this directory or inherited from a parent directory.
http://www.php.net/manual/en/features.file-upload.post-method.php see comments for $_FILES['userfile']['type']
April 18, 2012 - Issue reported to developers
April 19, 2012 - Fix committed to Collabtive github
May 30, 2012 - Collabtive version 0.7.6 released w/ fix
June 4, 2012 - Vulnerability published
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