Monday, January 26, 2009

L17: INTRODUCTION COMPUTER THREATS

The computer is a great tool to store important information. In certain cases, the information is very vital that losing it will harm the computer system.

Computer threats can come from many ways either from human or natural disasters. For example, when someone is stealing your account information from a trusted bank, this threat is considered as a human threat. However, when your computer is soaked in heavy rain, then that is a natural disaster threat.

MALICIOUS CODE
Malicious code is also known as a rogue program. It is a threat to computing assets by causing undesired effects in the programmer’s part. The effect is caused by an agent, with the intention to cause damage.

The agent for malicious code is the writer of the code, or any person who causes its distribution. There are various kinds of malicious code. They include virus, Trojan horse, logic door, trapdoor and backdoor, worm and many others.
a) VIRUS
• a program that can pass on the malicious code to other programs by modifying them
• attaches itself to the program, usually files with .doc, .xls and .exe extensions
• destroys or co-exists with the program
• can overtake the entire computing system and spread to other systems

b) TROJAN HORSE
• a program which can perform useful and unexpected action
• must be installed by users or intruders before it can affect the system’s assets
• an example of a Trojan horse is the login script that requests for users’ login ID and password
• the information is then used for malicious purposes

c) LOGIC BOMB
• logic bomb is a malicious code that goes off when a specific condition occurs.
• an example of a logic bomb is the time bomb
• it goes off and causes threats at a specified time or date

e) TRAPDOOR OR BACKDOOR
• a feature in a program that allows someone to access the program with special privileges

f) WORM
• a program that copies and spreads itself through a network

Primary Differences Between Worms And viruses

Worm Virus
Operates through the network Spreads through any medium
Spreads copies of itself as a standalone program Spreads copies of itself as a program that attaches to other
programs
HACKER
Hacking is a source of threat to security in computer. It is defined as unauthorised access to the computer system by a hacker. Hackers are persons who learn about the computer system in detail. They write program referred to as hacks. Hackers may use a modem or cable to hack the targeted computers.

NATURAL AND ENVIRONMENTAL THREATS
Computers are also threatened by natural or environmental disaster. Be it at home, stores, offices and also automobiles.Examples of natural and environmental disasters:
 Flood
 Fire
 Earthquakes, storms and tornados
 Excessive Heat
 Inadequate Power Supply

THEFT
Two types of computer theft:
1) Computer is used to steal money, goods, information and resources.
2) Stealing of computer, especially notebook and PDAs.

Three approaches to prevent theft:
1) prevent access by using locks, smart-card or password
2) prevent portability by restricting the hardware from being moved
3) detect and guard all exits and record any hardware transported

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