Config.action_controller.session_options[:cookie_only] = true

Rails
1

Recently, I got this security vulnerability on my app:

Ruby on Rails Multiple Method Session Fixation
Synopsis :

  The remote web server is affected by a session fixation

vulnerability.

  Description :

  The web server on the remote host appears to be a version of

Ruby on
Rails that supports URL-based sessions. An unauthenticated
remote
attacker may be able to leverage this issue to obtain an
authenticated
session.

  Note that Ruby on Rails version 1.2.4 was initially supposed to
  address this issue, but its session fixation logic only works

for the
first request, when CgiRequest is first instantiated.

  See also :

  http://weblog.rubyonrails.org/2007/10/5/rails-1-2-4-maintenance-release
  http://www.nessus.org/u?2f5b72e6
  http://dev.rubyonrails.org/ticket/10048
  http://www.nessus.org/u?1eeea9de

  Solution :

  Upgrade to Ruby on Rails version 1.2.6 or later and make sure
  'config.action_controller.session_options[:cookie_only]' is set

to
‘true’ in the ‘config/environment.rb’ file.

I checked my rails version: it is already 1.2.6. Then I un-comment
this line in environment.rb
config.action_controller.session_options[:cookie_only] = true

I got the following:

Error message:
You have a nil object when you didn’t expect it! You might have
expected an instance of Array. The error occurred while evaluating nil.
[]=
Exception class:
NoMethodError

Can anyone help me understand what is going on here?