Virus, information on hackers, worms, trojans, portscanning
An Introduction to Viruses
According to legend the Amjad brothers of Pakistan who ran a computer shop in the mid-eighties wrote the first computer virus. This was from their frustration with computer piracy. This first virus was a boot sector virus called Brain. Sine then an entire counter-culture industry of virus creation and distribution emerged, now there are several tens of thousands of viruses. With an estimated 200 new virus released every week.
Due to Hollywood files such as Independence Day or Hackers most people (even those without computers) are familiar with the term computer virus although it is worth pointing out most viruses described on films are highly exaggerated. Big Magazines and telly programs regularly run stories on dangerous viruses and we certainly seem fascinated by all of it.
Despite our awareness of computer virus there are not many of us who can define what one is, how it infects computers or what they are capable of doing, for example many people still believe the worst that can happen is having your hard drive formatted.
A computer virus is a program designed to spread itself by first infecting executable files or the system areas of hard and floppy disks and then making copies of itself. Viruses usually operate without the knowledge or desire of the computer user.
So Computer viruses are basically program modifications made to certain files that are designed to replicate on their own (say, when the host program file is executed). Viruses may or may not have a “payload” – a set of instructions that may be executed only under certain conditions, such as a particular date each year or after so many file “infections”. These instructions can range anywhere from displaying a message on the screen, changing data, to reformatting your hard drive or otherwise disabling (and, yes, damaging) your system. All viruses (destructive or not) rob your system of computing resources and have the potential of interfering with the normal functioning of your system.
A computer that has an active copy of a virus on its machine is considered infected.
Viruses have the potential to infect any type of executable code, not just the files that are commonly called ‘program files’. For example, some viruses infect executable code in the boot sector of floppy disks or in system areas of hard drives. Another type of virus, known as a ‘macro’ virus, can infect word processing and spreadsheet documents that use macros. And it’s possible for HTML documents containing JavaScript or other types of executable code to spread viruses or other malicious code.
When you execute program code that’s infected by a virus, the virus code will also run and try to infect other programs, either on the same computer or on other computers connected to it over a network. And the newly infected programs will try to infect yet more programs.
When you share a copy of an infected file with other computer users, Running the file may also infect their computers; and files from those computers may spread the infection to yet more computers. Different types of viruses infect computers in particular ways; the most widespread types are Macro,Boot and Parasitic viruses.