POODLE SSL3.0 Exploit (CVE-­2014-­3566)

You do not need to re-issue your SSL certificate because of POODLE.

Discovered by some Google techs and affectionally named POODLE the SSL3.0 bug is fairly serious and you need to give consideration about how to mitigate against potential attacks.

The official Advisory is CVE-­2014-­3566

Check if your site is vulnerable

Use this handy scanner to check: POODLE Scan

What is POODLE?

POODLE is an acronym of Padding Oracle On Downgraded Legacy Encryption (not sure how long it took them to come up with that). Basically an attacker could force a connection to downgrade to SSL3.0 and intercept secure HTTP cookies. This would require an effective man-in-the-middle style attack to take place first. More information along with technical details are available in the official document “Exploiting the SSL 3.0 Fallback

What is SSL3.0?

SSL was first used in the early 1990’s with the first version being SSL1.0. We then had SSL2.0 in 1995 and then SSL3.0 in 1996 which resolved many bugs and security issues in SSL2.0. At around this time the web became extremely popular and we had the glorious IE6 (more on that in a bit). The next release was in 1999 and brought us TLS1.0 (Transport Layer Security). While we still refer to SSL Certificates in most cases they use TLS to connect. We then had TLS1.1 in 2006 and since 2008 TLS1.2.

So SSL3.0 is effectively a 18+ year old technology. In technology terms that is centuries. However many servers still allow SSL3.0 connections to support legacy systems, such as IE6.0.

When attempting to negotiate a secure connection client and browser will generally try TSL1.2 first and then downgrade until it gets a successful connection. An attacker will attempt to force the downgrade to SSL3.0 to exploit the padding vulnerability and steal cookie information.

My site is Vulnerable!

If you find your site is vulnerable you may want to consider disabling SSL3.0. It is important to note the vulnerability affects users meaning that it may be possible to intercept the user cookies rather than exploit your website. This does mean your users are vulnerable.

Disabling SSL3.0 on Server

At this time the safest course of action is to disable SSL3.0. You will be essentially removing support for IE6 users but that browser is 18+ years old we have to let it go someday!

These articles should help you with disabling SSL3.0 on the server

  • Microsoft IIS
  • Apache (You can specify the protocols or use All -SSLv2 -SSLv3)
  • Nginx (Specify accepted protocols and exclude SSLv3)

Disabling SSL3.0 in your Browser

Be warned disabling SSL3.0 in your browser may prevent access to some websites. Take a look here for an excellent article on disabling SSL3.0 support in browsers. Firefox have also released an extension.

Relevant Further Reading