Arbitrary File Upload/Execution in Collabtive

TITLE: Arbitrary File Upload/Execution in Collabtive
DATE: 06-04-2012
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 ([email protected]/)
ADDITIONAL INFORMATION:
http://xync.org/2012/06/04/Arbitrary-File-Upload-in-Collabtive.html

Vulnerability:
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.

Fix:
Upgrade to Collabtive v0.7.6 or greater

Workaround:
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:
Options -Indexes
Options -ExecCGI
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.
See http://www.mysql-apache-php.com/fileupload-security.htm

Additional References:
http://xync.org/2012/06/04/Arbitrary-File-Upload-in-Collabtive.html

http://www.php.net/manual/en/features.file-upload.post-method.php see
comments for $_FILES['userfile']['type']

TIMELINE:
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