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(Page 3 of 10)
You also looked at the various types
of media likely to be found on (or near, or involved in some way with
your network, including:
- Coax, early Ethernet cabling, usually
either 10Base5, a thick cable up to 300 feet in length, or 10Base2,
a thin cable-TV-like cable up to 183 feet in length; security issues
include a lack of reliability and the ease with which coax can be tapped
and conversations eavesdropped upon.
- UTP/STP, unshielded and shielded twisted
pair cabling, used for Ethernet and Token Ring communications at speeds
from 4mb/sec to 1gb/sec or more; security issues with UTP include the
ease of adding devices to a UTP network by plugging a cable into any
spare hub or switch port, and vulnerability to eavesdropping by monitoring
electromagnetic emissions; if running cable in certain locations like
dropped ceilings, you need to use specially-approved cable that meets
fire codes, such as plenum cable.
- Fiber, fiber-optic cabling which transmits
data via light pulses rather than electrons, whose advantages include
being difficult to tap and immune to RF-based interference or snooping;
the main disadvantage is that fiber can be fragile and difficult to
work with, a situation which has been improving in recent years.
- Removable media, all types of data-storage
media which can be written to and then removed from the machine and
taken to another location; we look at these in detail below; the primary
vulnerabilities of removable media center around the lifetimes of media
for archival data storage as well as the potential for loss of confidential
data when the media gets into the wrong hands; to minimize data privacy
issues, you may want to encrypt data stored on removable media.
You reviewed the different types
of removable media, which include:
- Tape, one of the oldest media, and also
one of the slowest; tape is often used for system backups; it is prone
to becoming unreadable due to age/humidity/temperature and even tape
stretch, just like your favorite audio cassettes (if youre old
enough to remember such things!), and like all magnetic media is vulnerable
to data corruption from magnetic fields such as those from your computer
speakers, and may be difficult to FULLY erase.
- CD-R, which encompasses the original
CD-R technology as well as the later rewritable CD-RW technology; different
types of CD-R and CD-RW media have vastly differing expected lifetimes,
so do your research carefully; security vulnerabilities of CDR include
corruption via scratching the media, heat, humidity and direct sunlight;
it can also be difficult to fully erase data on a CDR, and some users
resort to scratching, breaking and even microwaving CDs to make
- Hard drives, which are available in two
common types, IDE and SCSI today; IDE is the low-cost leader, although
SCSI is the performance leader; hard drives may be either semi-permanently
installed inside a machine, or installed in removable carriers that
can easily be transported from machine to machine; hard drive security
issues include sensitivity to shock from being hit or dropped, corruption
due to magnetic fields, the amount of heat generated by the drive, lack
of hardware write protection for data written to drives;
like different kinds of CDR media, different manufacturers and brands
of hard drives have vastly differing MTBF, or mean time before failure,
- Diskettes, which are relatively low-capacity
media, so the risk of loss of substantial amounts of data via diskette
is minimal; older floppy diskettes were more vulnerable
to physical damage than todays hard-shelled diskettes; like other
magnetic media, they are vulnerable to corruption via EMF.
- Flashcards, which are more properly called
flash memory cards, use non-volatile memory which doesnt
require a constant power source, to store data; many PDAs and
digital cameras employ flash cards; since flashcards are available in
many different formats such as Compact Flash, Smart Media, Memory Stick,
MMC and Secure Digital, one concern is compatibility; other security
issues include vulnerability of theft of large amounts of data in a
small device, lack of support for encryption in some devices that read/write
data on flashcards, and limited media life.
- Smartcards, which are small credit-card
devices containing memory and possibly an IC for computations and data
encryption, with those that contain an IC costing more than the ones
just containing memory; smartcards typically store a small amount of
data such as 32K; they may be used for access control (card keys), authentication
(generating one time passwords) or storing e-cash (such as some schools
student ID cards; smartcard security issues include compatibility, vulnerability
to theft, the frequent need for multi-factor authentication, to augment
smartcard authentication with another type, for security purposes.
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CertiGuide for Security+ (http://www.CertiGuide.com/secplus/) on CertiGuide.com
Version 1.0 - Version Date: November 15, 2004
Adapted with permission from a work created by Tcat Houser et al.
CertiGuide.com Version © Copyright 2004 Charles M. Kozierok. All Rights Reserved.
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