Five Mistakes of Vulnerability Management

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'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 problem

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 resolve.

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, a security information management company.

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