Stop using self signed or invalid certificates

 

A posting to pastebin, but a group that calls itself “Cyber Warrior Team from Iran”, claims to have breached a NASA website via a “Man in the Middle” attack. The announcement is a bit hard to read due to the broken english, but here is how I parse the post and the associated screenshot:

The “Cyber Warrior Team” used a tool to scan NASA websites for SSL misconfigurations. They came across a site that used an invalid, likely self signed or expired certificate. Users visiting this web site would be used to seeing a certificate warning. This made it a lot easier to launch a man in the middle attack. In addition, the login form on the index page isn’t using SSL, making it possible to intercept and modify it unnoticed.

Once the attacker set up the man in the middle attack, they were able to collect username and passwords.

Based on this interpretation, the lesson should be to stop using self signed or invalid certificates for “obscure” internal web sites. I have frequently seen the argument that for an internal web site “it is not important” or “too expensive” or “too complex” to setup a valid certificate. SSL isn’t doing much for you if the certificate is not valid. The encryption provided by SSL only works if the authentication works as well. Otherwise, you never know if the key you negotiated was negotiated with the right party.

And of course, the log in form on the index page should be delivered via SSL as well. Even if the form is submitted via SSL, it is subject to tampering if it is delivered via http vs. https.

good old “OWASP Top 10” style lessons, but sadly, we still need to repeat them again and again. For a nice test to see if SSL is configured right on your site, see ssllabs.com .

Also, in more complex environments, you need to make sure that all of your SSL certificates are in sync. We recently updated SSL certificates, and forgot to update the one used by our IPv6 web server. (thnx Kees for pointing that out to us).

[1] http://pastebin.com/MFPMGZ4Z

[2] https://www.ssllabs.com

——
Johannes B. Ullrich, Ph.D.
SANS Technology Institute

 

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