Re: [Full-disclosure] Rails and redirections

[Timothy Goddard <tim@xxxxxxxxxxxxxx>]

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@xxxxxxxxx> 
Date:  
To: full-disclosure@xxxxxxxxxxxxxxxxx 
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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