Tag Archives: Skybox

An open letter to Ashley Carman, @SCMagazine, and @SkyboxSecurity

[Sent to Ashley directly via email. Posting for the rest of the world as yet another example of how vulnerability statistics are typically done poorly. In this case, a company that does not aggregate vulnerabilities themselves, and has no particular expertise in vulnerability metrics weighs in on 2013 "statistics". They obviously did not attend Steve Christey and my talk at BlackHat last year titled "Buying Into the Bias: Why Vulnerability Statistics Suck". If we do this talk again, we have a fresh example to use courtesy of Skybox.]

[Update: SkyboxSecurity has quickly written a second blog in response to this one, clarifying a lot of their methodology. No word from Carman or SC Magazine. Not surprised; they have a dismal history as far as printing corrections, retractions, or even addressing criticism.]


Ashley,

In your recent article “Microsoft leads vendors with most critical vulnerabilities“, you cite research that is factually incorrect, and I fully expect a retraction to be printed. In fact, the list of errata in this article is considerably longer than the article itself. Some of this may seem to be semantics to you, but I assure you that in our industry they are anything but. Read down, where I show you how their research is *entirely wrong* and Microsoft is not ‘number one’ here.

1. If Skybox is only comparing vendors based on their database, as maps to CVE identifiers, then their database for this purpose is nothing but a copy of CVE. It is important to note this because aggregating vulnerability information is considerably more demanding than aggregating a few databases that do that work for you.

2. You say “More than half of the company’s 414 vulnerabilities were critical.” First, you do not disclaim that this number is limited to 2013 until your last paragraph. Second, Microsoft had 490 disclosed vulnerabilities in 2013 according to OSVDB.org, apparently not one of the “20” sources Skybox checked. And we don’t claim to have all of the disclosed vulnerabilities.

3. You cite “critical vulnerability” and refer to Microsoft’s definition of that as “one that allows code execution without user interaction.” Yet Skybox did not define ‘critical’. This is amateur hour in the world of vulnerabilities. For example, if Microsoft’s definition were taken at face value, then code execution in a sandbox would still qualify, while being considerably less severe than without. If you go for what I believe is the ‘spirit’ of the research, then you are talking about vulnerabilities with a CVSS score of 10.0 (network, no user interaction, no authentication, full code execution to impact confidentiality / integrity / availability completely), then Microsoft had 10 vulnerabilities. Yes, only 10. If you add the ‘user interaction’ component, giving it a CVSS score of 9.3, they had 176. That is closer to the ‘216’ Skybox is claiming. So again, how can you cite their research when they don’t define what ‘critical’ is exactly? As we frequently see, companies like to throw around vulnerability statistics but give no way to reproduce their findings.

4. You say, “The lab’s findings weren’t particularly surprising, considering the vendors’ market shares. Microsoft, for instance, is the largest company and its products are the most widely used.” This is completely subjective and arbitrary. While Microsoft captures the desktop OS market share, they do not capture the browser share for example. Further, like all of the vendors in this study, they use third-party code from other people. I point this line out because when you consider that another vendor/software is really ‘number one’, it makes this line seem to
be the basis of an anecdotal fallacy.

5. You finish by largely parroting Skybox, “Skybox analyzed more than 20 sources of data to determine the number of vulnerabilities that occurred in 2013. The lab found that about 700 critical vulnerabilities occurred in 2013, and more than 500 of them were from four vendors.” We’ve covered the ‘critical’ fallacy already, as they never define what that means. I mentioned the “CVE” angle above. Now, I question why you didn’t challenge them further on this. As a security writer, the notion that “20” sources has any meaning in that context should be suspect. Did they simply look to 20 other vulnerability databases (that do all the initial data aggregation) and then aggregate them? Did they look at 20 unique sources of vulnerability information themselves (e.g. the MS / Adobe / Oracle advisory pages)? This matters greatly. Why? OSVDB.org monitors over 1,500 sources for vulnerability information. Monitoring CVE, BID, Secunia, and X-Force (other large vulnerability databases) is considered to be 4 of those sources. So what does 20 mean exactly? To me, it means they are amateurs at best.

6. Jumping to the Skybox blog, “Oracle had the highest total number of vulnerabilities at 568, but only 18 percent of their total vulnerabilities were deemed critical.” This is nothing short of a big red warning flag to anyone familiar with vulnerabilities. This line alone should have made you steer clear from their ‘research’ and demanded you challenge them. It is well known that Oracle does not follow the CVSS standards when scoring a majority of their vulnerabilities. It has been shown time and time again that what they scored is not grounded in reality, when compared to the
researcher report that is eventually released. Every aspect of a CVSS score is frequently botched. Microsoft and Adobe do not have that reputation; they are known for generally providing accurate scoring. Since that scoring is the quickest way to determine criticality, it is important to note here.

7. Now for what you are likely waiting for. If not Microsoft, who? Before I answer that, let me qualify my statements since no one else at this table did. Based on vulnerabilities initially disclosed in 2013, that have a CVSS score of 10.0 (meaning full remote code execution without user interaction), we get this:

Oracle: 48
Adobe: 29
Microsoft: 10

Two vendors place higher than Microsoft based on this. Now, if we consider “context-dependent code execution”, meaning that user interaction is required but it leads to full code execution (e.g. click this malicious PDF/DOC/GIF and we base that on a 9.3 CVSS score (CVSS2#AV:N/AC:M/Au:N/C:C/I:C/A:C”)) or full remote code execution (CVSS2#AV:N/AC:L/Au:N/C:C/I:C/A:C) we get the following:

Microsoft 176
Adobe: 132
Oracle: 122

I know, Microsoft is back on top. But wait…

ffmpeg: 326
libav: 286

Do you like apples?

Brian Martin
OSF / OSVDB.org

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