Industry Observations-Technical Insight

The Ghost of Information Disclosure

Information disclosure is a funny thing. Information disclosure can be almost completely innocuous or — as in the case of Heartbleed — it can be devastating. There is a new website called un1c0rn.net that aims to make hacking a lot easier by letting attackers utilize Heartbleed data that has been amassed into one place.

The business model is simple – 0.01 Bitcoins (Around $5) for data. It leaves

no traces on the remote server because the data isn’t stored there anymore,

it’s on un1c0rn’s server. So let’s play a sample attack out.

1) Heartbleed comes out;

2) Some time in the future un1c0rn scans a site that is vulnerable and logs it;

3) A would-be attacker searches through un1c0rn and finds a site of interest;

4) Attacker leverages the information to successfully mount an attack against the target server leveraging the data.

In this model, the attacker’s first packets to the server in question could be

the one that compromises them. But it’s actually more interesting than that. As I was looking through the data I found this query.

un1c0rn

For those of you who don’t live and breathe HTTP this is an authorization request with a base64 encoded string (which is trivial to reverse) that contains the usernames and passwords to the sites in question. This simple request found 400 sites with this simple flaw in it. So let’s play out another attack scenario.

1) Heartbleed comes out;

2) Some time in the future un1c0rn scans a site that is vulnerable and logs it;

3) Site is diligent and finds that they are vulnerable, patching up immediately and switching out their SSL certificate with a new one.

4) A would-be attacker searches through un1c0rn and finds a site of interest;

5) Using the information they found they still compromise the site with the username/password, even though the site is no longer vulnerable to the attack in question.

This is the problem with Information Disclosure – it still can be useful even long after the hole that was used to gather the data has been closed. That’s why in the case of Heartbleed and similar attacks not only do you have to fix the hole but you also have to expire all of the passwords, and remove all of the cookies or any other way that a user could gain access to the system.

The moral of the story is that you may find yourself being compromised seemingly almost magically in a scenario like this. How can someone guess a cookie correctly on the first attempt? Or guess a username/password on the first try? Or exploit a hole without ever having looked at your proprietary source code or even having visited your site before? Or find a hidden path to a directory that isn’t linked to from anywhere? Well, it may not be magic – it may be the ghost of Information Disclosure coming back to haunt you.

Spooky!