[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 ___ Full-Disclosure - We believe in it. Charter: http://lists.grok.org.uk/full-disclosure-charter.html Hosted and sponsored by Secunia - http://secunia.com/
Re: [Full-disclosure] Rails and redirections
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. Sent from Samsung Mobile Original message From: Brandon Perry bperry.volat...@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___ Full-Disclosure - We believe in it. Charter: http://lists.grok.org.uk/full-disclosure-charter.html Hosted and sponsored by Secunia - http://secunia.com/
Re: [Full-disclosure] Rails and redirections
I agree, an exception is the correct behavior. On Thu, Mar 6, 2014 at 2:10 PM, Timothy Goddard t...@goddard.net.nz wrote: 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. Sent from Samsung Mobile Original message From: Brandon Perry bperry.volat...@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 -- http://volatile-minds.blogspot.com -- blog http://www.volatileminds.net -- website ___ Full-Disclosure - We believe in it. Charter: http://lists.grok.org.uk/full-disclosure-charter.html Hosted and sponsored by Secunia - http://secunia.com/
Re: [Full-disclosure] Rails and redirections
FWIW this particular line has been present since early 2012. f52ad6cf actionpack/lib/action_controller/metal/redirecting.rb (Aaron Patterson 2012-03-15 14:56:50 -0700 106) end.gsub(/[\0\r\n]/, '') On Thu, Mar 6, 2014 at 7:11 PM, Brandon Perry bperry.volat...@gmail.comwrote: I agree, an exception is the correct behavior. On Thu, Mar 6, 2014 at 2:10 PM, Timothy Goddard t...@goddard.net.nzwrote: 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. Sent from Samsung Mobile Original message From: Brandon Perry bperry.volat...@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 -- http://volatile-minds.blogspot.com -- blog http://www.volatileminds.net -- website -- http://volatile-minds.blogspot.com -- blog http://www.volatileminds.net -- website ___ Full-Disclosure - We believe in it. Charter: http://lists.grok.org.uk/full-disclosure-charter.html Hosted and sponsored by Secunia - http://secunia.com/
