Category Archives: Vulnerability Statistics

2007 Top Vulnerable Vendors?,1895,2184206,00.asp

New IBM research shows that five vendors are responsible for 12.6 percent of all disclosed vulnerabilities. Not surprising: In the first half of 2007, Microsoft was the top vendor when it came to publicly disclosed vulnerabilities. Likely surprising to some: Apple got second place. IBM Internet Security Systems’ X-Force R&D team released its 2007 report on cyber attacks on Sept. 17, revealing that the top five vulnerable vendors accounted for 12.6 of all disclosed vulnerabilities in the first half of the yearor 411 of 3,272 vulnerabilities disclosed. Here’s the order in which the top 10 vendors stacked up, by percentage of vulnerabilities publicly disclosed in the first half of the year: Microsoft, 4.2 percent Apple, 3 percent Oracle, 2 percent Cisco Systems, 1.9 percent Sun Microsystems, 1.5 percent IBM, 1.3 percent Mozilla, 1.3 percent XOOPS, 1.2 percent BEA, 1.1 percent Linux kernel, 0.9 percent

This article was posted to ISN the other day and struck a nerve. How many times are we going to see vulnerability statistics presented without qualification? Rather than really get into the details, I replied with a single simple example on why such statistics are misleading at best and incorrect at worst. The bulk of my reply follows. My hopes for Lisa or IBM/ISS clarifying this is already dwindling.

One other factor, that Lisa Vaas apparently didn’t ask about, is how ISS X-Force catalogs vulnerabilities, and if their method and standards could impact these numbers at all. Take for example, two X-Force vulnerability database entries: Oracle Critical Patch Update – July 2007 18 CVE, 30+ Oracle Oracle Critical Patch Update – January 2007 30 CVE, 50+ Oracle So when comparing numbers, you have 2 X-Force entries that equate to 48 CVE entries that equate to *more than 80* unique and distinct vulnerabilities according to Oracle. I’m not a math or stat guy, but I have a feeling that this could seriously skew the statistics above, especially when you consider that Microsoft and Apple both have a more distinct breakdown and separation in the X-Force database. Anyone from IBM/ISS care to clarify? Lisa, did you have more extensive notes on this aspect that didn’t make it in the article perhaps?

Scrubbing the Source Data

A few months ago, Jeff Jones at CSO Online blogged about “Scrubbing the Source Data”, talking about the challenges of using vulnerability data for analysis. Part 1 examined using the National Vulnerability Database (NVD) showing how you can’t blindly rely on the data from VDBs. In his examples he shows that using the data to examine Windows is probably fairly accurate, yet examining Apple is less so and Ubuntu Linux is basically not possible. Unfortunately, there isn’t a part two to the series (yet) as implied by the title and introduction. Jones concludes the post:

Given these accuracy levels for vulnerabilities after the vendor has acknowledged it and provided a fix, it doesn’t seem like too much of a stretch to also conclude that using this data to analyze unpatched data would be equally challenging. Finally, I think this exercise helps demonstrate that anyone leveraging public data sources needs to have a good understanding of both the strengths and the weaknesses that any given data source may have, with respect to what one is trying to analyze or measure, and include steps in their methodology that accomodates accordingly.

McAfee: Microsoft patches 133 Critical/Important Vulns in 2006

McAfee is reporting that Microsoft patched 133 Critical / Important vulnerabilities in 2006. They also compare this number against previous years to presumably demonstrate that security isn’t getting better at Microsoft.

Oracle RDBMS vs Microsoft SQL Server


This paper will examine the differences between the security posture of Microsoft’s SQL Server and Oracle’s RDBMS based upon flaws reported by external security researchers and since fixed by the vendor in question. Only flaws affecting the database server software itself have been considered in compiling this data so issues that affect, for example, Oracle Application Server have not been included. The sources of information used whilst compiling the data that forms the basis of this document include:

The Microsoft Security Bulletins web page
The Oracle Security Alerts web page
The CVE website at Mitre.
The website

A general comparison is made covering Oracle 8, 9 and 10 against SQL Server 7, 2000 and 2005. The vendors� flagship database servers are then compared.


Vulnerability Type Distributions in CVE

Document version: 1.0 Date: October 4, 2006

For the past 5 years, CVE has been tracking the types of errors that lead to publicly reported vulnerabilities, and periodically reporting trends on a limited scale. In support of the Common Weakness Enumeration (CWE) project, and as a result of the interest in this work as mentioned during the “Year of the web application: Hack & Data from the Front lines” panel at the 5th Annual Cyber Security Executive Summit in New York City on September 13, 2006, we have published a more extensive analysis. An updated version will be released once 2006 is complete.

The primary goal of this study is to better understand research trends using publicly reported vulnerabilities. It should be noted that the data is obtained from an uncontrolled population, i.e., decentralized public reports from a research community with diverse goals and interests, with an equally diverse set of vendors and developers. More specialized, exhaustive, and repeatable methods could be devised to evaluate software security. But until such methods reach maturity and widespread acceptance, the overall state of software security can be viewed through the lens of public reports.


A Time to Patch III: Apple

A Time to Patch III: Apple

Over the past several months, Security Fix published data showing how long it took Microsoft and Mozilla to issue updates for security flaws. Today, I’d like to present some data I compiled that looks at Apple’s performance on this front.

Here’s what I found: Over the past two years, after being notified about serious security flaws in its products, it took Apple about 91 days on average to issue patches to correct those vulnerabilities. I also found that almost without exception, open-source Linux vendors were months ahead of Apple in fixing the same flaws.

You can download a copy of the charts I put together either in HTML format or as a Microsoft Excel file. I spent a long time on this research, but that doesn’t mean it is free of typos and so forth. If you spot one, or a discrepancy in the data, please drop me line and I will update the data as necessary.


Depending on how you count flaws..[..]/0,10801,109278,00.html

After flap, Symantec adjusts browser bug count
Depending on how you count flaws, either IE or Firefox could be considered less secure
News Story by Robert McMillan

MARCH 07, 2006 (IDG NEWS SERVICE) – A report issued today by Symantec Corp. seeks to satisfy users of both Mozilla Corp.’s Firefox browser and Microsoft Corp.’s Internet Explorer.

In its latest Internet Security Threat Report, covering the last six months of 2005, the company now features two different ways of counting browser bugs: one that finds that Internet Explorer has the most vulnerabilities, and a second that reveals Firefox as the bug leader.

Thank you Symantec, for generating completely useless vulnerability statistics. When you can manipulate them to support either side of an argument (and do so intentionally), what’s the point? Just define your criteria for counting a vulnerability, define your time frame, and let the results speak for themselves.

Mac vs Windows – More “Statistics”

Yet another article comparing Mac vs Windows, and using statistics to back it up. Since this is getting to be a common occurrence, I won’t go into the usual lecture about statistics, how they can easily be manipulated to back any argument (including how VAX/VMS is the most in/secure OS in the world!), how you must fully qualify the data you used to generate your statistics, and all the other tricks that make statistics the best tool to create a convincing argument (lie?). I’m not saying this because I think Mac or Windows is more or less secure. I’m saying this because I don’t feel the following article is accurate or well written. Even the readers who commented bring up some very valid points and questions for the author. Add to that it seems that the author (George Ou) is somewhat outspoken and a fan of Microsoft, his credibility and bias toward rivals comes into question. I’d love for Secunia to officially respond to this article, since he uses their database and rating system to generate his stats.

George Ou’s relevant conclusions: Between Feb 04 and Feb 06, Mac OS X had 5 “extremely critical” (1 unpatched) vulnerabilities and MS Windows had 2 “extremely critical” (0 unpatched) vulnerabilities. Mac OS X had 173 high and 59 moderate vulns, while MS Windows had 49 high and 41 moderate vulns. Ou goes to conclude “The data is clear, and Apple has a lot more vulnerabilities of every kind ranging from moderately critical to extremely critical.

Vulnerability statistics for Mac and Windows

One of many good comments challenging the piece:[..]messageID=356498&start=-1

Past criticism of Ou’s work, and signs he may be biased toward Microsoft:

A Time to Patch

Brian Krebs has a fantastic post on his blog covering the time it takes for Microsoft to release a patch, and if they are getting any better at it. Here are a few relevant paragraphs from it, but I encourage you to read the entire article. It appears to be a well developed article that is heavily researched and quite balanced. Makes me wonder if his editors shot it down for some reason. If they did, shame on them.

A few months back while researching a Microsoft patch from way back in 2003, I began to wonder whether anyone had ever conducted a longitudinal study of Redmond’s patch process to see whether the company was indeed getting more nimble at fixing security problems.

Finding no such comprehensive research, Security Fix set about digging through the publicly available data for each patch that Microsoft issued over the past three years that earned a “critical” rating. Microsoft considers a patch “critical” if it fixes a security hole that attackers could use to break into and take control over vulnerable Windows computers.

Here’s what we found: Over the past three years, Microsoft has actually taken longer to issue critical fixes when researchers waited to disclose their research until after the company issued a patch. In 2003, Microsoft took an average of three months to issue patches for problems reported to them. In 2004, that time frame shot up to 134.5 days, a number that remained virtually unchanged in 2005.

First off, these are the kind of statistics and research that I mean when I talk about the lack of evolution of vulnerability databases. This type of information is interesting, useful, and needed in our industry. This begins to give customers a solid idea on just how responsive our vendors are, and just how long we stay at risk with unpatched vulnerabilities. This is also the type of data that any solid vulnerability database should be able to produce with a few clicks of the mouse.

This type of article can be written due to the right data being available. Specifically, a well documented and detailed time line of the life of a vulnerability. Discovery, disclosure to the vendor, vendor acknowledgement, public disclosure, and patch date are required to generate this type of information. People like Steven Christey (CVE) and Chris Wysopal (VulnWatch) have been pushing for this information to be made public, often behind the scenes in extensive mail to vendors. In the future if we finally get these types of statistics for all vendors over a longer period of time, you will need to thank them for seeing it early on and helping to make it happen.

This type of data is of particular interest to OSVDB and has been worked into our database (to a degree) from the beginning. We currently track the disclosure date, discovery date and exploit publish date for each vulnerability, as best we can. Sometimes this data is not available but we include it when it is. One of our outstanding development/bugzilla entries involving adding a couple more date fields, specifically vendor acknowledge date and vendor solution date. With these five fields, we can begin to trend this type of vendor response time with accuracy, and with a better historical perspective.

While Krebs used Microsoft as an example, are you aware that other vendors are worse than Microsoft? Some of the large Unix vendors have been slow to patch for the last twenty years! Take the recent disclosure of a bug in uustat on Sun Microsystems Solaris Operating System. iDefense recently reported the problem and included a time line of the disclosure process.

08/11/2004 Initial vendor contact
08/11/2004 Initial vendor response
01/10/2006 Coordinated public disclosure

Yes, one year and five months for Sun Microsystems to fix a standard buffer overflow in a SUID binary. The same thing that has plagued them as far back as January 1997 (maybe as far back as December 6, 1994, but details aren’t clear). It would be nice to see this type of data available for all vendors on demand, and it will be in due time. Move beyond the basic stats and consider if we apply this based on the severity of the vulnerability. Does it change the vendor’s response time (consistently)? Compare the time lines along with who discovered the vulnerability, and how it was disclosed (responsibly or no). Do those factors change the vendor’s response time?

The answers to those questions have been on our minds for a long time and are just a few of the many goals of OSVDB.

Open Letter on the Interpretation of “Vulnerability Statistics”

Steve Christey (CVE Editor) wrote an open letter to several mailing lists regarding the nature of vulnerability statistics. What he said is spot on, and most of what I would have pointed out had my previous rant been more broad, and not a direct attack on a specific group. I am posting his entire letter here, because it needs to be said, read, understood, and drilled into the heads of so many people. I am reformatting this for the blog, you can read an original copy via a mail list.

Open Letter on the Interpretation of “Vulnerability Statistics”

Author: Steve Christey, CVE Editor
Date: January 4, 2006

As the new year begins, there will be many temptations to generate, comment, or report on vulnerability statistics based on totals from 2005. The original reports will likely come from publicly available Refined Vulnerability Information (RVI) sources – that is, vulnerability databases (including CVE/NVD), notification services, and periodic summary producers.

RVI sources collect unstructured vulnerability information from Raw Sources. Then, they refine, correlate, and redistribute the information to others. Raw sources include mailing lists like Bugtraq, Vulnwatch, and Full-Disclosure, web sites like PacketStorm and Securiteam, blogs, conferences, newsgroups, direct emails, etc.

In my opinion, RVI sources are still a year or two away from being able to produce reliable, repeatable, and COMPARABLE statistics. In general, consumers should treat current statistics as suggestive, not conclusive.

Vulnerability statistics are difficult to interpret due to several factors:

  • – VARIATIONS IN EDITORIAL POLICY. An RVI source’s editorial policy dictates HOW MANY vulnerabilities are reported, and WHICH vulnerabilities are reported. RVIs have widely varying policies. You can’t even compare an RVI against itself, unless you can be sure that its editorial policy has not changed within the relevant data set. The editorial policies of RVIs seem to take a few years before they stabilize, and there is evidence that they can change periodically.
  • – FRACTURED VULNERABILITY INFORMATION. Each RVI source collects its information from its own list of raw sources – web sites, mailing lists, blogs, etc. RVIs can also use other RVIs as sources. Apparently for competitive reasons, some RVIs might not identify the raw source that was used for a vulnerability item, which is one aspect of what I refer to as the provenance problem. Long gone are the days when a couple mailing lists or newsgroups were the raw source for 90% of widely available vulnerability information. Based on what I have seen, the provenance problem is only going to get worse.
  • – LACK OF COMPLETE CROSS-REFERENCING BETWEEN RVI SOURCES. No RVI has an exhaustive set of cross-references, so no RVI can be sure that it is 100% comprehensive, even with respect to its own editorial policy. Some RVIs compete with each other directly, so they don’t cross-reference each other. Some sources could theoretically support all public cross-references – most notably OSVDB and CVE – but they do not, due to resource limitations or other priorities.
  • – UNMEASURABLE RESEARCH COMMUNITY BIAS. Vulnerability researchers vary widely in skill sets, thoroughness, preference for certain vulnerability types or product classes, and so on. This collectively produces a bias that is not currently measurable against the number of latent vulnerabilities that actually exist. Example: web browser vulnerabilities were once thought to belong to Internet Explorer only, until people actually started researching other browsers; many elite researchers concentrate on a small number of operating systems or product classes; basic SQL injection and XSS are very easy to find manually; etc.
  • – UNMEASURABLE DISCLOSURE BIAS. Vendors and researchers vary widely in their disclosure models, which creates an unmeasurable bias. For example, one vendor might hire an independent auditor and patch all reported vulnerabilities without publicly announcing any of them, or a different vendor might publish advisories even for very low-risk issues. One researcher might disclose without coordinating with the vendor at all, whereas another researcher might never disclose an issue until a patch is provided, even if the vendor takes an inordinate amount of time to respond. Note that many large-scale comparisons, such as “Linux vs. Windows,” can not be verified due to unmeasurable bias, and/or editorial policy of the core RVI that was used to conduct the comparison.


This is just a sample of variations in editorial policy. There are legitimate reasons for each variation, usually due to audience needs or availability of analytical resources.

COMPLETENESS (what is included):

  1. SEVERITY. Some RVIs do not include very low-risk items such as a bug that causes path disclosure in an error message in certain non-operational configurations. Secunia and SecurityFocus do not do this, although they might note this when other issues are identified. Others include low-risk issues, such as CVE, ISS X-Force, US-CERT Security Bulletins, and OSVDB.
  2. VERACITY. Some RVIs will only publish vulnerabilities when they are confident that the original, raw report is legitimate – or if they’re verified it themselves. Others will publish reports when they are first detected from the raw sources. Still others will only publish reports when they are included in other RVIs, which makes them subject to the editorial policies of those RVIs unless care is taken. For example, US-CERT’s Vulnerability Notes have a high veracity requirement before they are published; OSVDB and CVE have a lower requirement for veracity, although they have correction mechanisms in place if veracity is questioned, and CVE has a two-stage approach (candidates and entries).
  3. PRODUCT SPACE. Some RVIs might omit certain products that have very limited distribution, are in the beta development stage, or are not applicable to the intended audience. For example, version 0.0.1 of a low-distribution package might be omitted, or if the RVI is intended for a business audience, video game vulnerabilities might be excluded. On the other hand, some “beta” products have extremely wide distribution.
  4. OTHER VARIATIONS. Other variations exist but have not been studied or categorized at this time. One example, though, is historical completeness. Most RVIs do not cover vulnerabilities before the RVI was first launched, whereas others – such as CVE and OSVDB – can include issues that are older than the RVI itself. As another example: a few years ago, Neohapsis made an editorial decision to omit most PHP application vulnerabilities from their summaries, if they were obscure products, or if the
    vulnerability was not exploitable in a typical operational configuration.

    ABSTRACTION (how vulnerabilities are “counted”):

  5. VULNERABILITY TYPE. Some RVIs distinguish between types of vulnerabilities (e.g. buffer overflow, format string, symlink, XSS, SQL injection). CVE, OSVDB, ISS X-Force, and US-CERT Vulnerability Notes perform this distinction; Secunia, FrSIRT, and US-CERT Cyber Security Bulletins do not. Bugtraq IDs vary. As vulnerability classification becomes more detailed, there is more room for variation (e.g. integer overflows and off-by-ones might be separated from “classic” overflows).
  6. REPLICATION. Some RVIs will produce multiple records for the same core vulnerability, even based on the RVI’s own definition. Usually this is done when the same vulnerability affects multiple vendors, or if important information is released at a later date. Secunia and US-CERT Security Bulletins use replication; so might vendor advisories (for each supported distribution). OSVDB, Bugtraq ID, CVE, US-CERT Vulnerability Notes, and ISS X-Force do not – or, they use different replication than others. Replication’s impact on statistics is not well understood.
  7. OTHER VARIATIONS. Other abstraction variations exist but have not been studied or categorized at this time. As one example, if an SQL injection vulnerability affects multiple executables in the same product, OSVDB will create one record for each affected program, whereas CVE will combine them.


  8. RVIs differ in how quickly they must release vulnerability information. While this used to vary significantly in the past, these days most public RVIs have very short timelines, from the hour of release to within a few days. Vulnerability information can be volatile in the early stages, so an RVI’s requirements for timeliness directly affects its veracity and completeness.


  9. All RVIs deal with limited resources or time, which significantly affects completeness, especially with respect to veracity, or timeliness (which is strongly associated with the ability to achieve completeness). Abstraction might also be affected, although usually to a lesser degree, except in the case of large-scale disclosures.


In my opinion:

You should not interpret any RVI’s statistics without considering its editorial policy. For example, the US-CERT Cyber Security Bulletin Summary for 2005 uses statistics that include replication. (As a side note, a causal glance at the bulletin’s contents makes it clear that it cannot be used to compare Windows to Linux as operating systems.)

In addition, you should not compare statistics from different RVIs until (a) the RVIs are clear about their editorial policy and (b) the differences in editorial policy can be normalized. Example: based on my PRELIMINARY investigations of a few hours’ work, OSVDB would have about 50% more records than CVE, even though it has the same underlying number of vulnerabilities and the same completeness policy for recent issues.

Third, for the sake of more knowledgeable analysis, RVIs should consider developing and publishing their own editorial policies.
(Note that based on CVE’s experience, this can be difficult to do.) Consumers should be aware that some RVIs might not be open about their raw sources, veracity analysis, and/or completeness.

Finally: while RVIs are not yet ready to provide usable, conclusive statistics, there is a solid chance that they will be able to do so in the near future. Then, the only problem will be whether the statistics are properly interpreted. But that is beyond the scope of this letter.

Steve Christey
CVE Editor

P.S. This post was written for the purpose of timely technical exchange. Members of the press are politely requested to consult me before directly attributing quotes from this article, especially with respect to stated opinion.