[MajorSecurity #26] Woltlab Burning Board - Multiple Cookie manipulation and session fixation vulnerabilities


[MajorSecurity #26] Woltlab Burning Board - Multiple Cookie manipulation and session fixation vulnerabilities ---------------------------------------------------------------------------------------- Software: Woltlab Burning board Impact: Cookie manipulation and Session Fixation Made public: July, 23th 2006 Vendor: WoltLab GmbH Page: http://www.woltlab.de Credits: ---------------------------------------------- Discovered by: David Vieira-Kurz http://www.majorsecurity.de Original Advisory: ---------------------------------------------- http://www.majorsecurity.de/advisory/major_rls26.txt Affected products: ------------------------------------------------- Woltlab Burning board 1.1.1 Woltlab Burning Board 1.2 Woltlab Burning Board 2.1.3 Woltlab Burning Board 2.1.5 Woltlab Burning Board 2.2 Woltlab Burning Board 2.2.1 Woltlab Burning Board 2.2.2 Other versions may also be affected... Requirements: ------------------------------------------------- register_globals = On Cookie manipulation and session fixation attack: ------------------------------------------------- Classification: Session Fixation is an attack technique that forces a user's session ID to an explicit value. Depending on the functionality of the target web site, a number of techniques can be utilized to "fix" the session ID value. These techniques range from Cross-site Scripting exploits to peppering the web site with previously made HTTP requests. After a user's session ID has been fixed, the attacker will wait for them to login. Once the user does so, the attacker uses the predefined session ID value to assume their online identity. Vulnerability: ------------------------------------------------- WBB 1.1.1 and 1.2: The Cookie variable "sid" can be set to something like: 1. <meta+http-equiv='Set-cookie'+content='cookiename=cookievalue'>;sthreads=a%253A1%253A%257Bi%253A0%253BN%253B%257D 2. sid=>'><script>alert(123456789)</script>;sthreads=a%253A1%253A%257Bi%253A0%253BN%253B%257D // XSS is possible 3. Cookie: sid='";sthreads=a%253A1%253A%257Bi%253A0%253BN%253B%257D // SQL-Injection could be possible WBB 2.1.x and 2.2.x: The Cookie variable "wbb2_lastvisit" can be set to something like: Cookie: wbb2_cookiehash=0bb23efeb1a979d68027994ecb29fc48;wbb2_lastvisit=>'><script>alert(123456789)</script>;wbb2_hidecats=a%253A1%253A%257Bi%253A19%253Bi%253A0%253B%257D // XSS is possible Cookie: wbb2_cookiehash=0bb23efeb1a979d68027994ecb29fc48;wbb2_lastvisit=%00';wbb2_hidecats=a%253A1%253A%257Bi%253A19%253Bi%253A0%253B%257D Solutions: ------------------------------------------------- 1. Do not accept session identifiers from GET / POST variables: Session identifiers in URL (query string, GET variables) or POST variables are not recommended as it simplifies this attack - it is easy to make links or forms which sets GET / POST variables. 2.Regenerate SID on each request: A powerful countermeassure against session fixation is to "regenerate" session identifier (SID) on each request. This means that although attacker may trick a user into accepting a known SID, the SID will be invalid when attacker attempts to re-use the SID. 3. Accept only server generated SID: One way to improve security is to not accept session identifiers not generated by server. if ( ! is_set( $_SESSION['SERVER_GENERATED_SID'] ) ) { session_destroy(); // destroy all data in session } session_regenerate_id(); // generate a new session identifier $_SESSION['SERVER_GENERATED_SID'] = true; References: ------------------------------------------------- http://www.acrossecurity.com/papers/session_fixation.pdf http://www.webappsec.org/projects/threat/classes/session_fixation.shtml http://en.wikipedia.org/wiki/Session_fixation