Page 204 - CISSO_Prep_ Guide

activities. A denial of service attack aims at disabling the
systems or operations of the target. There have been many ways
to conduct network-based DoS attacks including the Ping of
Death (a malformed ICMP ping packet), SMURF (a flood of
ICMP packets), Fraggle (a flood of UDP packets), SYN floods
(a flood of TCP SYN requests), and NTP (Network Time
Protocol) floods, to name a few!

A DoS can also be against other systems or services - for
example, an organization that is subject to a strike by their staff
will often find it difficult for other workers or customers to gain
access to the building.

A DDoS or Distributed Denial of Service attack is a denial of
service attack launched from many points at once against a
target. The use of many systems to attack a target amplifies the
attack and can be difficult to defend against.

Botnets

Botnets, or robotically-controlled networks, are one of the
largest problems on the internet today. A botnet is a collection
of compromised devices that have been infected with a program
that allows them to be accessed and manipulated remotely. The
infection may be through a ‘zombie’ that sits on a victim’s
machine and listens on an Internet Relay Chat (IRC) channel or
through a program such as Zeus (also known as ZBOT) or
Citadel that allows an attacker to read everything being done on
the victim’s machine. ZBOT is often used in financial fraud,
whereas many zombies are used in the distribution of spam or
malicious content.