The paper I'll comment in this post was presented on
ACM's
Conference on Computer and Communications Security held on
Oct. 16-18, 2012. The paper tries to answer the following question:
How long, on average, does zero-day attack last before it is publicly disclosed? This is one of those questions, which when you see them are so obvious, but for some strange reason they didn't occur to you. And what's more, no one else didn't try to tackle them! In the same time this is a very important question from security defense perspective!
Anyway, having an idea is one thing, to realize it is completely another. And in this paper, the authors did both very well!
In short, it is an excellent paper with a lot of information to digest! So, I strongly recommend anyone who's in security field to study it carefully. I'll put here some notes what I found novel and/or interesting while I was reading it. Note that for someone else, something else in the paper may be interesting or novel, and thus this post is definitely not replacement for reading the paper yourself. Also, if you search a bit on the Internet you'll find that others also
covered this paper.
Contributions
The contributions of this paper are:
- Analysis of dynamics and characteristics of zero-day attacks, i.e. how long it takes before zero-day attacks are discovered, how many hosts are targeted, etc.
- A method to detect zero-day attacks based by correlating anti-virus signatures of malicious code that exploits certain vulnerabilities with a database of binary file downloads across 11 million hosts on the Internet.
- Analysis of impact of vulnerability disclosure on number of attacks and their variations. In other words, what happens when new vulnerability is disclosed, how exactly does that impact number and variations of attacks.
Findings and implications
The key finding of this research is that zero day attacks are discovered, on average, 312 days after they first appeared. But in one case it took 30 months to discover the vulnerability that was exploited. Next finding is that zero day attacks, by themselves, are quite targeted. There are of course exceptions, but majority of them hit only several hosts. Next, after vulnerability is disclosed there is a surge of new variants of exploits as well as number of attacks. The number of attacks can be five orders of magnitude higher after they've been disclosed than before.
During their study, the authors found 11 not previously known zero-day attacks. But be careful, it isn't a statement that they found vulnerabilities now previously known. It means there are known vulnerabilities, but up to this point (i.e. this research) it wasn't know that those vulnerabilities were used for zero-day attacks.
So, here is my interpretation of implications of these findings. This means that currently there are at least dozen exploits in the wild no one is aware of. So, if you are a high profile company, this means that you are in a serious trouble. Now, as usual, everything depends on many things are you, or will you, be attacked. Next, when there is a disclosure of a vulnerability and there is no patch available, you have to be very careful because at that point there is a surge of attacks.