Opinion by Anton Chuvakin
JANUARY 11, 2006
Vulnerability management is viewed by some as an esoteric security
management activity. Others see it as a simple process that needs to
be done with Microsoft Corp.'s monthly patch update. Yet another group
considers it a marketing buzzword made up by vendors.
This article will look at common mistakes that organizations make on
the path to achieving vulnerability management perfection, both in
process and technology areas.
No. 1: Scanning but failing to act
The first mistake is scanning for vulnerabilities, but then not acting
on the results. Vulnerability scanners have become a staple at many
organizations. Scanning technology has matured in recent years, and
the tools' accuracy, speed and safety have improved dramatically.
However, modern commercial and open-source scanners still suffer from
the same disease that troubled early intrusion-detection systems
(IDS): They are too noisy, since they produce too many alerts, for
various reasons. In addition, they don't tell you what you should do
about those vulnerability notices, just as most IDSs don't tell you
whether you should care about a particular alert.
Thus, vulnerability management is not scanning; it includes it, but
what happens after the scan is even more important. This includes
asset inventory, prioritizing and researching the remediation
activities as well as the actual act of patching, hardening or
reconfiguration. A detailed explanation of all the important
activities goes beyond the scope of this article.
No. 2. Thinking that patching is the same as vulnerability management
It's true that patching is the way to repair many widespread
vulnerabilities. Even some industry experts proclaim that
vulnerability management is simple: Just patch all those pesky
problems, and you're done.
However, many vulnerabilities can't be fixed by simply updating to the
latest product version. They require tweaking and reconfiguring
various system parameters. Indeed, vulnerability management was born
out of a need to intelligently prioritize and fix discovered
vulnerabilities, whether by patching or other means.
So if you are busy every second Tuesday but not doing anything to
eliminate a broad range of enterprise vulnerabilities during the other
29 days in a month, you are not managing your vulnerabilities.
No. 3. Believing that vulnerability management is only a technical
If you think that vulnerability management is only a technical
problem, then you're in for a surprise. To be effective, it also
involves attention to policy and process improvements. In fact,
focusing on process and the "softer" side of the vulnerability
conundrum will often bring more benefits than a high-tech patch
management system. There are many glaring weaknesses in IT policies
and infrastructures. Let's not forget that policy weaknesses are
vulnerabilities, too. For example, if you do not enforce a policy for
a minimum password length, you have a clear policy weakness that
scanners are not likely to discover and that patching will not
Thus, weak passwords, lack of data-confidentiality awareness and lack
of a standard, hardened, workstation configuration can do more to ruin
your security posture and increase your risk than any single hole in a
piece of software.
According to Gartner analysts, "the vulnerability management process
includes policy definition, environment baselining, prioritization,
shielding, mitigation as well as maintenance and monitoring."
Indeed, the vulnerability management process starts from a policy
definition document that covers an organization's assets (such as
systems and applications) and their users. Such a document and the
accompanying security procedures should define the scope of the
vulnerability management effort as well as postulate a "known good"
state of those IT resources.
No. 4. Assessing a vulnerability without looking at the whole picture
The fourth mistake is committed by those who try to follow a proper
vulnerability management process, but when they get to the critical
challenge of prioritizing the vulnerabilities, they ignore the threat
angle of the prioritization. Namely, they try to assess the importance
of the vulnerabilities (and, thus, the urgency of their response)
based only on the vulnerabilities themselves without looking at the
threat profiles and business roles of the affected systems.
For example, a Web server with an unpatched vulnerability deployed in
the DMZ where it is subject to constant probing and attacks needs to
be patched much sooner than a test system deep in the bowels of the
enterprise. At the same time, a critical finance system that is not
attacked frequently but contains data critical to the company's
viability (something like the infamous "Coca-Cola formula") also needs
to be in the first round of patching.
One way to avoid this mistake is to use the risk formula Risk = Threat
x Vulnerability x Value and use the results of such a formula to
decide what to patch first. Using a security information management
product that implements such vulnerability scoring will help to
automate such a process.
To intelligently prioritize vulnerabilities for remediation, you need
to take into account various factors about your own IT environment as
well as the outside world. They include the following:
* Vulnerability severity for the environment
* Related threat information and threat relevance
* Business value and role information about the target systems
Recently, a new standard was proposed to classify vulnerability
severity and help organizations prioritize their remediation efforts.
The Common Vulnerability Scoring System (CVSS) takes into account
various vulnerability properties, such as priority, exploitability and
impact. The CVSS plan promises to provide a uniform way of scoring
vulnerabilities, as soon as it is adopted by more vulnerability
information providers. However, CVSS data still needs to be enhanced
with business-value and threat data.
Business information is vital for vulnerability prioritization, since
it ties the technical threat and vulnerability data into the business
function. Every organization is different and thus has different
critical assets and applications. Attacks against some of them might
cripple the business; others will only cause a brief interruption in
noncritical operations. In reality, however, life is not that simple,
and a vulnerability in a less-critical system could be used as a
stepping stone to later compromise a more-critical one.
No. 5: Being unprepared for the unknown -- "zero-day exploits"
The fifth mistake, zero-day exploits, gives shivers to many
knowledgeable security managers. While I've noticed a lot of confusion
about what constitutes a zero-day exploit, the main idea is that it is
an exploit that uses a previously undisclosed vulnerability. So, even
if you patch all the known software vulnerabilities, you can still be
attacked and compromised by intruders who exploit undisclosed flaws.
What can you do? Apart from a sensible vulnerability management
program, which includes a hefty amount of hardening that might protect
against zero day exploits and careful network and host security
monitoring that might make you aware that you've been hit you need to
make sure that the incident response plans are in order. Such cases
need to be addressed by using the principle of "defense in depth"
during the security infrastructure design. Get your incident
management program organized and primed for a response to such attack.
Anton Chuvakin, GCIA, GCIH, GCFA is a security strategist with
NetForensics Inc., a security information management company. He is
co-author of Security Warrior (O'Reilly Media Inc., 2004) and a
contributor to Know Your Enemy, Second Edition, Information Security
Management Handbook and the upcoming Hacker's Challenge 3. He has
published papers on a broad range of security subjects. In his spare
time, he maintains his security portal and a blog at O'Reilly.com.
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