 Using Freeware
Vulnerability Scanners
Gary Bahadur and Yen-ming Chen
Vulnerabilty scanners are all the rage in the security industry. Some scan
externally for weaknesses, and others perform host-based scanning and everything
in between. If you have ever used Cybercop (http://www.nai.com)
or ISS Safesuite (http://www.iss.net),
you know these products can be expensive. There are alternatives that do not
cost a lot of money, but how do you know which ones are best and how do you
find them?
In this article, we will briefly describe the methodology of using vulnerability
scanners and give some freeware options for the security-minded administrator.
There are a number of pros and cons to using freeware versus commercial products,
and the validity of even performing security testing. The three products discussed
in this article are Nessus (http://www.nessus.org),
Narrow Security Scanner (http://www.packetstorm.securify.com/UNIX/scanners/nss/),
and SAINT (http://www.wwdsi.com/saint/).
The usage of these products is placed in the context of performing a security
review and these are just a sample of available products.
To secure a site, a logical progression must be followed. Downloading a scanner
and executing it against your network is only part of the solution. For a comprehensive
security review, the following steps must be taken:
- Footprint Analysis — Scan the environment for operating systems, applications,
and services running.
- Vulnerability Analysis — Determine potential vulnerabilities in services,
applications, and operating systems.
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