Front cover - IBM Redbooks

3.1 The need for secure infrastructures
98 Lotus Security Handbook
Just like we might provide different barriers for protecting our personal property,
we need to ensure that we have “adequate and appropriate” security barriers for
our organization’s information systems. By this we mean that, in the simplest
sense, there are multiple protection methods employed at various points in the
infrastructure design to thwart potential attacks. These methods involve a design
that provides several layers of defense. For the purpose of this discussion, the
term “layer” is generic and could represent something physical or something
logical.
For example, a layered-defense approach to protecting your car from theft could
include keeping it in a locked garage, keeping the doors locked, and using a
steering wheel immobilizing lock. But whether or not this is “adequate and
appropriate” is relative. For a person who owns an older model car and lives in
an isolated location, we hope you’d agree that the protection is perhaps above
and beyond what is deemed adequate, so in that sense it may not be
appropriate. On the other hand, the owner of a museum-worthy collectible car,
living in a high-crime area, might agree our example’s layers of protection are
appropriate but less than adequate.
The analogy of protecting a car is a very simplistic illustration of layers of
defense. We can extend the layered-defense analogy by adding or modifying
layers, such as adding alarm systems, perimeter fences, magnetic card building
access, video surveillance, and so forth. However, the analogy of protecting a
physical object such as a car is still overly simplistic since it is concerned with
outright theft only. In the context of IT, “theft” of data is just one of many
concerns, and it has a whole different meaning since data can be copied while
leaving the original in place. Several additional aspects of security apply to
information technology systems and the data residing and flowing within and
outside the organization. These information security issues include broad
concepts, such as confidentiality and integrity. For example, unauthorized
access to data falls under confidentiality, while malicious alteration or deletion of
data falls under integrity.
This chapter presents an overview of security requirements that an infrastructure
must be capable of supporting. It also provides some common-sense guidelines
for infrastructure defense measures, and a “top-down” model of layers of
defense.