08-06-2013, 02:35 PM
COMPUTER VIRUSES
COMPUTER VIRUSES.doc (Size: 122.5 KB / Downloads: 18)
Introduction
Computer viruses are called viruses because they share some of the traits of biological viruses. A computer virus passes from computer to computer like a biological virus passes from person to person.
There are similarities at a deeper level, as well. A biological virus is not a living thing. A virus is a fragment of DNA inside a protective jacket. Unlike a cell, a virus has no way to do anything or to reproduce by itself -- it is not alive. Instead, a biological virus must inject its DNA into a cell. The viral DNA then uses the cell's existing machinery to reproduce itself. In some cases, the cell fills with new viral particles until it bursts, releasing the virus. In other cases, the new virus particles bud off the cell one at a time, and the cell remains alive.
A computer virus shares some of these traits. A computer virus must piggyback on top of some other program or document in order to get executed. Once it is running, it is then able to infect other programs or documents. Obviously, the analogy between computer and biological viruses stretches things a bit, but there are enough similarities that the name sticks.
Types Of Viruses
When you listen to the news, you hear about many different forms of electronic infection. The most common are:
Viruses - A virus is a small piece of software that piggybacks on real programs. For example, a virus might attach itself to a program such as a spreadsheet program. Each time the spreadsheet program runs, the virus runs, too, and it has the chance to reproduce (by attaching to other programs) or wreak havoc.
E-mail viruses - An e-mail virus moves around in e-mail messages, and usually replicates itself by automatically mailing itself to dozens of people in the victim's e-mail address book.
The latest thing in the world of computer viruses is the e-mail virus, and the Melissa virus in March 1999 was spectacular. Melissa spread in Microsoft Word documents sent via e-mail, and it worked like this:
Someone created the virus as a Word document uploaded to an Internet newsgroup. Anyone who downloaded the document and opened it would trigger the virus. The virus would then send the document (and therefore itself) in an e-mail message to the first 50 people in the person's address book. The e-mail message contained a friendly note that included the person's name, so the recipient would open the document thinking it was harmless. The virus would then create 50 new messages from the recipient's machine. As a result, the Melissa virus was the fastest-spreading virus ever seen! As mentioned earlier, it forced a number of large companies to shut down their e-mail systems.
Origin Of Viruses
People create viruses. A person has to write the code, test it to make sure it spreads properly and then release the virus. A person also designs the virus's attack phase, whether it's a silly message or destruction of a hard disk. So why do people do it?
There are at least three reasons. The first is the same psychology that drives vandals and arsonists. Why would someone want to bust the window on someone else's car, or spray-paint signs on buildings or burn down a beautiful forest? For some people that seems to be a thrill. If that sort of person happens to know computer programming, then he or she may funnel energy into the creation of destructive viruses.
The second reason has to do with the thrill of watching things blow up. Many people have a fascination with things like explosions and car wrecks. When you were growing up, there was probably a kid in your neighborhood who learned how to make gunpowder and then built bigger and bigger bombs until he either got bored or did some serious damage to himself. Creating a virus that a spread quickly is a little likes that -- it creates a bomb inside a computer, and the more computers that get infected the more "fun" the explosion.
The third reason probably involves bragging rights, or the thrill of doing it. Sort of like Mount Everest. The mountain is there, so someone is compelled to climb it. If you are a certain type of programmer and you see a security hole that could be exploited, you might simply be compelled to exploit the hole yourself before someone else beats you to it. "Sure, I could TELL someone about the hole. But wouldn't it be better to SHOW them the hole?" That sort of logic leads to many viruses.
VIRUS ACTIONS
The only way to deal with these threats is to secure all remaining gaps in WAP security, before such attacks are mounted. The industry is in a unique position to benefit from past experience and proactively prevent the type of weaknesses in infrastructure that caught us unaware with past computer incidents. There are no viruses on WAP yet – we still have time to react.
Before we consider the key security issues, and solutions that will help identify and meet WAP content security risks, it is best to understand how a basic WAP network is composed. There are three logical components: the WAP client (or mobile terminal), the WAP gateway and the origin server. The origin server is located in the traditional
Internet domain and functions like an ordinary Web server by providing storage for WAP content. The WAP gateway interconnects the Internet domain with the mobile network domain by providing the mobile terminal with Internet access. The mobile terminal roams in the mobile network and sends encoded content requests to the origin server via the WAP gateway. WAP needs more functionality in order to be useful and for it to really take off the ground.
PROTECTION AGAINST VIRUS
The Symbian OS (operating system) smart phones will provide on-device protection, similar in fashion to antivirus protection programs for PCs, with automatic over-the-air antivirus updates for a monthly fee. The software will not come loaded into the device, but can be downloaded from the F-Secure Web site, according to Nokia .The Nokia 6670 will be the first mobile phone in its Series 60 line to offer the mobile virus protection, though users of other Series 60 mobile phones will also be able to purchase the antivirus protection software.
F-Secure is also in talks with other handset manufacturers about offering similar antivirus protection. He declined to name any companies or set out potential dates for availability. This announcement is a starting point for us and we have been testing the service with a variety of handsets from different vendors and in several operator networks.
Nokia, based in Espoo, Finland, already offers antivirus software through F-Secure for its Communicator line of mobile devices, but the protection offered for the Nokia 6670 is a greatly improved version in terms of both features and pricing options.