Computer Security

Today the computer has replaced the gun and knife as the weapon of choice of many criminals. Computer crime is often defined as any crime accomplished through the knowledge or use of computer technology. Nobody knows the true extent of computer crimes.

Many crimes go undetected. Those which are detected often go unreported, because business fear that they can loss more from negative publicity than from the actual crimes. But it is a fact that both businesses and the governmental agencies loss huge amounts of money every year to computer criminals.
Types of computer crimes:
Software piracy:

Piracy or the illegal duplication of copyrighted software is the most common computer crime. Millions of computer users have made copies of programs that they have not legally bought. Now that most software companies have given in to user demands and removed physical copy protection from their products, copying software is as easy as duplicating a cassette tape or photocopying a book. Many people do this because they are not aware that this unauthorized copying is illegal; but many people do fully aware that they are doing something illegal.

Software/Hardware :

Another type of computer crime is sabotage of hardware or software. The word sabotage comes from the early days of industrial revolution, when rebellious workers damaged new machines by kicking wooden shoes, called sabots, into the gears. However, modern computer saboteurs use software rather than footwear for their destructive activities. They use viruses, worms, logic bombs and Trojan horses to destroy the computer hardware and software.

Hacking and electronic trespassing:

In the late 1970s, timesharing computers at Standford University and Massachusetts Institute of technology attracted informal communicaties of computer fanatics who called themselves hackers. In those days a hacker was a person who enjoyed learning the details of computer systems and writing clever programs-referrec to as hacks.

But today hackers are not so innocent and have very ominous intentions. They enter corporate and government computers using stolen passwords and security loopholes and steal information, transfer money to their accounts, and do a lot of other criminal activities. Sometimes they use modems to dial up the target computers directly; in other cases they 'trave' to their destinations through the internet and other networks. Many hackers over their tracks and leave without a trace; but many leave logic bombs, viruses and do a lot of malicious activities like changing passwords, shutting down or crippling the system. A growing number of hackers are part of the electronic crime rings intent on stealing credit card numbers and other sensitive information and this kind of theft is difficult to detect because, the criminals usually leave behind no evidence of their visit.


Two inherent characteristics of virus:

• A computer will do exactly what it is programmed to do, including revealing sensitive information. Any system than can be programmed can be reprogrammed by anyone with sufficient knowledge.
• Any computer can do only what it is programmed to do, it cannot protect itself from either malfunctions or deliberate attacks unless such events have been specifically anticipated and countered with appropriate programming.

Malicious computer programs:
This is the third type of computer crime, where our system can be sabotaged without anybody being physically present. Some types of computer programs find their way into your computer, and carry out their instructions without your knowledge. These programs may be begin, simply printing a message on the screen, or they may be malicious, reformatting your hard disk at an inopportune moment.
A worm is a program, which copies itself over and over, eventually causing the computer to crash when it runs out of RAM/ or hard disk space. An unfortunate incident occurred. A Trojan horse is a program, which appears to have a useful function, but really has a secret malicious one. A classic example is the "SEXY ladies" program for the Macintosh. Certainly the name inspires a lot of people to double-click on its icon. Instead of being rewarded with pictures of sexy ladies, though, its users get to see a "gotcha" message, and shortly thereafter, find that the data on their hard disk is gone. A bomb is a virus, which waits a certain period of time before executing its code. It may wait for the user to access the computer a predetermined number of times before activating,or it may wit for a particular date.


Defending against malicious programs:
We can buy or download anti-virus software, which scan disks and inform you of any prgorams it finds which looks like viruses or other malicious programs. In most cases you will be able to remove the virus without harming files.
Some anti-virus programs can be trained to scan a disk before the computer reads any data from it. This way the virus never has a chance to infect system. It is important to update anti virus software regularly. An anti virus program written yesterday can't work for tomorrow.