Feel free to send it along and we'll take a look.

Cheers,
Scott


On Fri, Feb 26, 2010 at 9:55 AM, Felix Reinel <[email protected]> wrote:

> Hi Scott,
> > If you think you have found a security vulnerability, please contact
> > Jasig at this address:
> > http://www.ja-sig.org/wiki/display/JSG/Security+Contact+Group
> Alright, they're on CC now.
> >
> > You *should* provide an appropriate level of detail:
> > * CAS Version
> > * Any customizations, etc.
> The version tested was the latest CAS 3 version. I see that there is a
> custom JSP page in the installation I was testing with.
> >
> > The default JSP page for CAS uses the Spring Form tag which appears to
> > properly parse the action (at least in my testing in Firefox using the
> > URL you provided).
> If you can confirm this does not work with the default JSP, it's not
> really a security problem of CAS itself indeed. I think I have to say
> sorry for the noise.
>
> However, it would be nice if somebody of you could have a quick look in
> a possible fix for this custom JSP I have here offline as I'm not really
> deep into JSP, just send me an email in case...
>
> Thanks in advance,
> Felix
> >
> >
> > On Fri, Feb 26, 2010 at 4:28 AM, Felix Reinel <[email protected]
> > <mailto:[email protected]>> wrote:
> >
> >     Dear all,
> >
> >     it looks like the CAS server is lacking input validation for the
> >     'security_check' parameter, which leads to a cross-site-scripting
> >     vulnerability.
> >
> >     By performing a POST request like this:
> >     echo 'POST
> >     /sso/login?service=http://
> $SERVER/$APPLICATION/security_check"><script>alert("vulnerable_to_xss")</script>'
> >     | nc $SERVER $PORT | grep '<script>'
> >
> >     it seems to be possible to inject java-script code as can be seen
> >     in the
> >     response, containing the following html code inside the form
> >     action tag:
> >
> action="login;jsessionid=2A2EBF7AF213F90375F2713CF0DD0C59?service=http://
> $SERVER/$APPLICATION/security_check"><script>alert("vulnerable_to_xss")</script>">
> >
> >     I guess the fix would be perform proper encoding of that parameter?
> >     Would be great if you could have a look into that.
> >
> >     Best regards,
> >     Felix Reinel
> >
>
> --
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> Felix Reinel               |  Web & Systems Administrator
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>
>
>

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