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General Security Concepts: Access Control, Authentication, and Auditing • Chapter 1 39

This is applicable for any type of operating system.The Security+ exam is
operating system agnostic, meaning that the same general principles apply regardless
of the operating system that you use. Being familiar with the services that are
unnecessary for the specific operating system that you are working with is an
important part of ensuring that the system is well secured.The basic premise is to
disable the services that you do not need.The list of services that this covers varies
by operating system or even the specific version or release of the operating system.

Non-essential Protocols

Non-essential protocols can provide the opportunity for an attacker to reach or
compromise your system.These include network protocols such as Internetwork
Packet Exchange/Sequenced Packet Exchange (IPX/SPX or in Windows Operating
Systems, NWLink) and NetBIOS Extended User Interface (NetBEUI). It also
includes the removal of unnecessary protocols such as Internet Control Messaging
Protocol (ICMP), Internet Group Management Protocol (IGMP), and specific
vendor supplied protocols such as Cisco’s Cisco Discovery Protocol (CDP), which is
used for communication between Cisco devices, but may open a level of vulnera-
bility in your system. Evaluation of protocols used for communication between net-
work devices, applications, or systems that are proprietary or used by system device
manufacturers, such as the protocols used by Cisco to indicate private interior gate-
ways to their interoperating devices, should also be closely examined.
Evaluation of the protocols suggested for removal may show that they are
needed in some parts of the system, but not others. Many OS platforms allow the
flexibility of binding protocols to certain adaptors and leaving them unbound on
others, thus reducing the potential vulnerability level.
Disabling Non-essential Systems

While working with the development and growth of networks and environments,
we often retain older systems and leave them active within the overall system.This
can be a serious breach, as we may not pay attention to these older systems and
keep them up to date with the latest security patches and tools. It is important to
realize that older systems, particularly those whose use is extremely low, should
have a planned decommissioning policy in place. Systems not necessary for your
particular operation should be disabled, removed, and sterilized with good informa-
tion removal practices before being recycled, donated, or destroyed.

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