Vulnerability assessments may be broken down into one of two types: Outside looking in and inside looking around.
When performing an outside looking in vulnerability assessment you are attempting to compromise your systems from the outside. Being external to your company provides you with the cracker's viewpoint. You see what a cracker sees — publicly-routable IP addresses, systems on your DMZ, external interfaces of your firewall, and more.
When you perform an inside looking around vulnerability assessment you are somewhat at an advantage since you are internal and your status is elevated to trusted. This is the viewpoint you and your co-workers have once logged on to your systems. You see print servers, file servers, databases, and other resources.
There are striking distinctions between these two types of vulnerability assessments. Being internal to your company gives you elevated privileges — more so than any outsider. Still today in most organizations, security is configured in such a manner as to keep intruders out. Very little is done to secure the internals of the organization (such as departmental firewalls, user-level access controls, authentication procedures for internal resources, and more). Typically, there are many more resources when inside looking around as most systems are internal to a company. Once you set yourself outside the company, you immediately are given untrusted status. The systems and resources available to you externally are typically much more limited.
Consider the difference between vulnerability assessments and penetration tests. Think of a vulnerability assessment as the first step to a penetration test. The information gleaned from the assessment will be used in the testing. Whereas, the assessment is checking for holes and potential vulnerabilities, the penetration testing actually attempts to exploit the findings.
Assessing network infrastructure is a dynamic process. Security, both information and physical, is dynamic. Performing an assessment shows an overview, which can turn up false positives and false negatives.
Security administrators are only as good as the tools they use and the knowledge they retain. Take any of the assessment tools currently available, run them against your system, and it is almost a guarantee that there will be at least some false positives. Whether by program fault or user error, the result is the same. The tool may find vulnerabilities which in reality do not exist (false positive); or, even worse, the tool may not find vulnerabilities that actually do exist (false negative).
Now that the difference between vulnerability assessment and penetration test is defined, it is often good practice to take the findings of the assessment and review them carefully before conducting a penetration test.
Attempting to exploit vulnerabilities on production resources can have adverse effects to the productivity and efficiency of your systems and network.
The following list examines some of the benefits to performing vulnerability assessments.
Proactive focus on information security
Finding potential exploits before crackers find them
Typically results in systems being kept up to date and patched
Promotes growth and aids in developing staff expertise
Financial loss and negative publicity abated
To aid in the selection of tools for vulnerability assessment, it is helpful to establish a vulnerability assessment methodology. Unfortunately, there is no predefined or industry approved methodology at this time; however, common sense and best practices can act as a sufficient guide.
What is the target? Are we looking at one server, or are we looking at our entire network and everything within the network? Are we external or internal to the company? The answers to these questions are important as they will help you determine not only which tools to select but also the manner in which the they will be used.
To learn more about establishing methodologies, refer to the following websites: