How to Verify the Rails CookieStore Session Termination Weakness

I want to try it out myself you say.

Here is a video explanation using as an example:


And here are the steps you take to verify the weakness yourself–using, as well as on other websites you suspect are using Rails’ CookieStore (such as those on this list):

  1. Install a Chrome plugin such as Edit This Cookie to make viewing and editing cookies easier.
  2. Go to a site such as (no SSL!) or one you suspect is using Rails’ CookieStore.
  3. Find a cookie whose value starts with “BAh7″. That’s a good indicator of Ruby on Rails CookieStore-based websites before version 4.0 of Rails, or those that don’t encrypt their CookieStore values. The session cookie will have a value starting with “BAh7″ then a separator of “–” then a hash digest.
  4. Open Edit This Cookie using the little icon in the top right of your browser. Find the cookie whose value starts with “BAh7″ and take note of the cookie’s name. In the case of it’s “_ksr_session”. Copy the entire cookie data (“BAh7…”).
  5. Screen Shot 2013-11-24 at 12.01.20 PM

  6. Log out of the website.
  7. Open Edit This Cookie and overwrite the session cookie’s current value (“_ksr_session” in this case) with the data you copied previously.
  8. Go to the website. You should be in again!

One thought on “How to Verify the Rails CookieStore Session Termination Weakness

  1. Pingback: Ruby on Rails CookieStore flaw exposes thousand of websites

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