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Broadband Risks
Confidentiality, integrety, and availability are three main ideas that
form up the core of computer security.
These concepts apply
to home Internet users just as much as they would to any corporate or
government network. You probably wouldn't let a stranger look through
your important documents. In the same way, you may want to keep the tasks
you perform on your computer confidential, whether it's tracking your
investments or sending email messages to family and friends. Also, you
should have some assurance that the information you enter into your computer
remains intact and is available when you need it.
Some security risks
arise from the possibility of intentional misuse of your computer by intruders
via the Internet. The bad news is that you probably cannot plan for every
possible risk. The good news is that you can take some simple steps to
reduce the chance that you'll be affected by the most common threats.
Let's take a closer
look at some of these risks.
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. In most cases, the latest patches
will prevent the attack.
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. 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 that can be used in DoS attacks as mentioned
above.
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.
We recommend that you do so if you are browsing web sites that you are
not familiar with or do not trust.
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. Email spoofing
Email "spoofing" is when an email message appears to have originated
from one source when it actually was sent from another source. Email spoofing
is often an attempt to trick the user into making a damaging statement
or releasing sensitive information (such as passwords).
Spoofed email can range from harmless pranks to social engineering ploys.
Examples of the latter include
- Email claiming
to be from a system administrator requesting users to change their passwords
to a specified string and threatening to suspend their account if they
do not comply
- Email claiming
to be from a person in authority requesting users to send them a copy
of a password file or other sensitive information
Note that while service providers may occasionally request that you
change your password, they usually will not specify what you should
change it to. Also, most legitimate service providers would never ask
you to send them any password information via email. If you suspect
that you may have received a spoofed email from someone with malicious
intent, you should contact your service provider's support personnel
immediately.
9. Email borne
viruses
Viruses and other types of malicious code are often spread as attachments
to email messages. Before opening any attachments, be sure you know the
source of the attachment. It is not enough that the mail originated from
an address you recognize. The Melissa virus spread precisely because it
originated from a familiar address. Also, malicious code might be distributed
in amusing or enticing programs.
Never run a program
unless you know it to be authored by a person or company that you trust.
Also, don't send programs of unknown origin to your friends or coworkers
simply because they are amusing -- they might contain a Trojan horse program.
10. Hidden file
extensions
Windows operating systems contain an option to "Hide file extensions
for known file types". The option is enabled by default, but a user
may choose to disable this option in order to have file extensions displayed
by Windows. Multiple email-borne viruses are known to exploit hidden file
extensions. The first major attack that took advantage of a hidden file
extension was the VBS/LoveLetter worm which contained an email attachment
named "LOVE-LETTER-FOR-YOU.TXT.vbs". Other malicious programs
have since incorporated similar naming schemes.
Examples include:
- Downloader (MySis.avi.exe
or QuickFlick.mpg.exe)
- VBS/Timofonica
(TIMOFONICA.TXT.vbs)
- VBS/CoolNote (COOL_NOTEPAD_DEMO.TXT.vbs)
- VBS/OnTheFly (AnnaKournikova.jpg.vbs)
The files attached
to the email messages sent by these viruses may appear to be harmless
text (.txt), MPEG (.mpg), AVI (.avi) or other file types when in fact
the file is a malicious script or executable (.vbs or .exe, for example).
11. Chat clients
Internet chat applications, such as instant messaging applications and
Internet Relay Chat (IRC) networks, provide a mechanism for information
to be transmitted bi-directionally between computers on the Internet.
Chat clients provide groups of individuals with the means to exchange
dialog, web URLs, and in many cases, files of any type.
Because many chat
clients allow for the exchange of executable code, they present risks
similar to those of email clients. As with email clients, care should
be taken to limit the chat client's ability to execute downloaded files.
As always, you should be wary of exchanging files with unknown parties.
12. 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 local area network.
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.
Avoid
Disaster!
Now that you better
understand the risks of a broadband Internet connection, do
something to protect yourself!
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