We have touched on many of the more common vulnerabilities found in today's
computing environment. There are numerous other vulnerabilities associated with
operating systems and applications. We have seen a common theme in our
recommended procedures to deal with each vulnerability—monitor for and install
system patches as they become available. Each month between 20 and 70 new
vulnerabilities are published on the Internet. There is a critical time period
between the publication of the vulnerability and the application of the patch
that needs to be managed. In addition, security monitoring of intrusion
detection systems and system logs can detect attacks as they occur and enable
the organization to respond accordingly. Appropriate incident response
procedures may prevent the attack from being successful or may help to minimize
and contain any potential damage.
While vendors are generally responsive in publishing newly discovered
vulnerabilities and the patches or procedures to address them, system
administrators do not have time to visit each vendor Web site on a daily or even
weekly basis. There are mailing lists such as CERT, Bugtraq, and others that
will notify subscribers as new vulnerabilities are published. However, the
e-mails cover all systems and can be overwhelming to read and sort through.
Fortunately, there are services to help system administrators monitor and locate
system patches. Vulnerability subscription services provide information on the
new vulnerabilities as they become published. The level of information included
with the services varies from a straight listing of vulnerabilities to
searchable databases to customized profiles that e-mail you when a new
vulnerability affecting your profile is published. Subscribing to or monitoring
one of these services is the only way to keep up to date with emerging
vulnerabilities. There are several free services that publish new
vulnerabilities as they are found. Sites such as Security Focus (www.securityfocus.com), eSecurityonline (www.esecurityonline.com), and the Computer Security Division
of the National Institute for Standards and Technologies (NIST) ICAT (http://csrc.nist.gov/icat/) site contain searchable databases of
vulnerabilities. Searchable databases enable administrators to look for new
vulnerabilities related to products they use. Many of the databases enable a
user to search by operating system, application, severity, date, and other
fields.
While these searchable vulnerability databases provide a starting point for
system administrators trying to track new vulnerabilities, they do not
completely solve the problem. One of the biggest problems for the system
administrator trying to monitor newly emerging vulnerabilities is time. Even
using sites that e-mail vulnerabilities tends to overwhelm administrators with
e-mail of vulnerabilities that do not pertain to the systems under their
control. Using services that are customizable and notify system administrators
when a new vulnerability emerges that affects their systems is a way
administrators can save time in addressing vulnerabilities on a regular
basis.
Cutting down on the work involved with vulnerability monitoring is a step in the right direction. However, to eliminate the exposures to new vulnerabilities, an enforcement mechanism is needed to validate that identified vulnerabilities are addressed and repaired in a timely manner. Testing using the techniques and tools described in this book is one method of enforcement. Even these steps require quite a bit of structure and coordination to be effective over time. Automated security scans and monitoring cut down on the time required to determine whether security exposures have been addressed. Regular scans using tools such as Cybercop, ISS Internet Scanner, or Nessus will help in this area. Configuration management tools such as Symantec's Omniguard Enterprise Security Manager (ESM) provide another enforcement mechanism. These tools are not cheap, but the implications of not plugging security holes regularly are not cheap either.
Cutting down on the work involved with vulnerability monitoring is a step in the right direction. However, to eliminate the exposures to new vulnerabilities, an enforcement mechanism is needed to validate that identified vulnerabilities are addressed and repaired in a timely manner. Testing using the techniques and tools described in this book is one method of enforcement. Even these steps require quite a bit of structure and coordination to be effective over time. Automated security scans and monitoring cut down on the time required to determine whether security exposures have been addressed. Regular scans using tools such as Cybercop, ISS Internet Scanner, or Nessus will help in this area. Configuration management tools such as Symantec's Omniguard Enterprise Security Manager (ESM) provide another enforcement mechanism. These tools are not cheap, but the implications of not plugging security holes regularly are not cheap either.
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