Full Disclosure: Re: Rails and redirections

[Timothy Goddard <tim () goddard net nz>]

Very interesting, could cause issues. It can't use the value and not substitute - that's worse. Have seen response 
splitting in mod_perl because it outputs raw strings in to location headers. In my view it should raise an exception if 
not a valid URI.


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-------- Original message --------
From: Brandon Perry <bperry.volatile () gmail com> 
Date:  
To: full-disclosure () lists grok org uk 
Subject: [Full-disclosure] Rails and redirections 
 

Currently, passing \0, \r, or \n into a URL that is passed to redirect_to has Rails gsub'ing them out of the URL before 
completing the redirect.

A programmer that doesn't realise this is happening could easily write a regex and logic that says "if url starts with 
https:// or http:// fail or else redirect_to url".

Seems straighforward, but an attacker could simply pass in a url like \nhttp://www.google.com and bypass the regex 
check and be redirected to google.com.

The line effecting this is line 106 in redirecting.rb in Rails.

https://github.com/rails/rails/blob/3-2-stable/actionpack/lib/action_controller/metal/redirecting.rb#L106

I feel like this is something that Rails should not be doing on behalf of the programmer. The programmer should be 
expected to pass in exactly what they want redirected to without Rails changing their data. Should this be considered a 
vulnerability?

Thoughts?

-- 
http://volatile-minds.blogspot.com -- blog
http://www.volatileminds.net -- website

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