I'd like to add a few notes here on forcing clearPass to only be available
via proxy authentication. 

 

I recently discovered that turning off the casAuthenticationFilter alone
is not sufficient to disable clearPass from directly rendering credentials
on the page. It is still possible for clearPass to render credentials on
the page using the following URL:

https://sso.server.edu/cas/login?service=https://sso.server.edu/cas/clearP
ass 

 

This is seemingly due to the fact that the Java CAS client and
specifically its proxy-enabled validation filter allows for an empty proxy
chain that is constructed by the above URL. Until the next CAS client
release, the quick remedy is to provide an extension of the
'Cas20ProxyTicketValidator' which would be responsible to disallowing
empty proxy chains. 

 

Regards, 

-Misagh



 

From: Domazlicky, Eric [mailto:[email protected]] 
Sent: Wednesday, December 05, 2012 10:04 AM
To: [email protected]
Subject: [cas-user] Note to ClearPass users of CAS 3.5

 

I would recommend to any users of CAS 3.5 with ClearPass configured to
take a look at the changes in the pull request for CAS-1209:

https://issues.jasig.org/browse/CAS-1209

https://github.com/Jasig/cas/pull/151

 

Basically the pull request removes the CAS Authentication Filter from
clearPass-configuration.xml. If you don't remove the CAS Authentication
filter your user's cleartext passwords can be disclosed if an attacker
gains access to their browser session and visits the clearPass URL
(usually https://server.edu/cas/clearPass). With the CAS Authentication
Filter disabled in clearPass-configuration.xml, the remaining CAS Proxy
Filter protects against an attacker seeing the cleartext password, even if
they gain access to the user's browser session by use of the
allowedProxyChains attribute. 

 

This may seem like a pretty remote security issue since the attacker has
to gain access to the users' browser session first. But at least in a
Higher Ed environment I think this happens more than we realize (students
walking away from computers without logging off etc..). 

 

---

Eric Domazlicky

Portal/E-Mail Administrator

Tacoma Community College

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