The most common methods used by Hackers

The most common methods used by intruders to gain control of home
computers are briefly described below.

1. Trojan horse programs

Trojan horse programs are a common way for intruders to trick you
(sometimes referred to as "social engineering") into installing "back
door" programs. These can allow intruders easy access to your
computer without your knowledge, change your system configurations,
or infect your computer with a computer virus.

2. Back door and remote administration programs

On Windows computers, three tools commonly used by intruders to
gain remote access to your computer are BackOrifice, Netbus, and
SubSeven. These back door or remote administration programs, once
installed, allow other people to access and control your computer.

3. Denial of service

Another form of attack is called a denial-of-service (DoS) attack. This
type of attack causes your computer to crash or to become so busy
processing data that you are unable to use it. It is important to note that
in addition to being the target of a DoS attack, it is possible for your
computer to be used as a participant in a denial-of-service attack on
another system.

4. Being an intermediary for another attack

Intruders will frequently use compromised computers as launching
pads for attacking other systems. An example of this is how distributed
denial-of-service (DDoS) tools are used. The intruders install
an "agent" (frequently through a Trojan horse program) that runs on
the compromised computer awaiting further instructions. Then, when a
number of agents are running on different computers, a single "handler"
can instruct all of them to launch a denial-of-service attack on another
system. Thus, the end target of the attack is not your own computer,
but someone else’s -- your computer is just a convenient tool in a larger

attack.

5. Unprotected Windows shares

Unprotected Windows networking shares can be exploited by intruders
in an automated way to place tools on large numbers of Windows-
based computers attached to the Internet. Because site security on the
Internet is interdependent, a compromised computer not only creates
problems for the computer's owner, but it is also a threat to other sites
on the Internet. The greater immediate risk to the Internet community
is the potentially large number of computers attached to the Internet
with unprotected Windows networking shares combined with distributed
attack tools.
Another threat includes malicious and destructive code, such as viruses
or worms, which leverage unprotected Windows networking shares to
propagate.
There is great potential for the emergence of other intruder tools that
leverage unprotected Windows networking shares on a widespread
basis.

6. Mobile code (Java/JavaScript/ActiveX)

There have been reports of problems with "mobile code" (e.g. Java,
JavaScript, and ActiveX). These are programming languages that
let web developers write code that is executed by your web browser.
Although the code is generally useful, it can be used by intruders
to gather information (such as which web sites you visit) or to run
malicious code on your computer. It is possible to disable Java,
JavaScript, and ActiveX in your web browser.

7. Cross-site scripting

A malicious web developer may attach a script to something sent to a
web site, such as a URL, an element in a form, or a database inquiry.
Later, when the web site responds to you, the malicious script is
transferred to your browser.
You can potentially expose your web browser to malicious scripts by
following links in web pages, email messages, or newsgroup postings
without knowing what they link to
using interactive forms on an untrustworthy site
viewing online discussion groups, forums, or other dynamically

generated pages where users can post text containing HTML tags

8. Packet sniffing

A packet sniffer is a program that captures data from information
packets as they travel over the network. That data may include
user names, passwords, and proprietary information that travels
over the network in clear text. With perhaps hundreds or thousands
of passwords captured by the packet sniffer, intruders can launch
widespread attacks on systems. Installing a packet sniffer does not
necessarily require administrator-level access.
Relative to DSL and traditional dial-up users, cable modem users have
a higher risk of exposure to packet sniffers since entire neighborhoods
of cable modem users are effectively part of the same LAN. A packet
sniffer installed on any cable modem user's computer in a neighborhood
may be able to capture data transmitted by any other cable modem in
the same neighborhood.