Squiz MySource Matrix Unauthorised Proxy and Cross Site Scripting

aushack.com - Vulnerability Advisory

Release Date:
22-Sep-2006

Software:
Squiz - My Source and My Source Matrix
http://www.squiz.net.au

"MySource Matrix is the newest version of the popular MySource CMS,
purpose built for enterprise level installations. It boasts all the
features of high-end systems such as highly configurable workflow,
a powerful integrated search engine, intuitive front-end editing, true
rollback and much more."

Versions affected:
MySource Matrix 3.8 and below, MySource 2.x.

Vulnerability discovered:

MySource Matrix may be used as an unauthorised HTTP proxy (and XSS).

Vulnerability impact:

Low - An anonymous user may use the MySource based website as a proxy.
Additionally, proxied bandwidth may be at great financial expense.
Remote content may contain JavaScript which is client executed.

Vulnerability information

A function of the software 'sq_remote_page_url' allows inclusion of remote
content in the body of the website.

Example: (wrapped)
http://www.mysource-example.com.au/$page?sq_remote_page_action=
fetch_url&sq_remote_page_url=http://www.google.com.au

… where '$page' is a valid CMS reference, e.g. 'about_us'.

This will return the Google website, encapsulated in the header
and footer HTML of the www.mysource-example.com.au site.

The remote page may contain JavaScript for XSS purposes, e.g. cookies.

Remote PHP inclusion does not appear to be possible (returns % hex value).

One could write a script to enable a world wide anonymous proxy array.

Solution:
The vendor does not consider this a vulnerability. Newer versions of the
software include a function 'sq_content_src' to hide the URL (Base64),
in addition to use of a string whitelist to permit inclusion, for example:

if whitelist = http://www.trust-content.com/index?id=*, where * = <wildcard>
ok = http://www.trust-content.com/index?id=1234
bad = http://www.trust-content.com/index?ref=1234

Note that whilst the URL is Base64 encoded, this does not necessarily mean
that whitelists are used. Future releases may be proxied via:

http://www.mysource-example.com.au/$page?
sq_content_src=aHR0cDovL3d3dy5nb29nbGUuY29tLmF1

References:
aushack.com advisory
http://www.aushack.com/advisories/200607-mysourcematrix.txt

Credit:
Patrick Webster ( [email protected] )

Disclosure timeline:
27-Apr-2006 - Discovered during audit, Squiz notified shortly after.
07-Jun-2006 - Sent security patch query to Squiz developers.
09-Jun-2006 - Squiz response - use whitelist function.
22-Sep-2006 - Public disclosure.

EOF