protect computer from attack foreign programs

Your computer is a waiting playground for viruses and malicious malware. The controllers of these evil entities would like nothing more than to get inside the confines of your hard drive and take over your domain. The virus creators are lurking in the shadows waiting for their chance to infiltrate your encampment.
You must protect your computer from attack by these evil entities. In order to protect your system and keep your computer running like it should you are going to need to have a firewall in place. A firewall will prevent a lot of the intruders. There will be some persistent threats that will find a way around your firewall, but for the most part you will be protected as long as your firewall is enabled and running.
Antivirus software was created to detect and capture any threats that make it past your firewall. The antivirus software that you have will keep threatening programs that slip past your firewall from doing harm to your system.

avoiding virus infections

Install anti-virus software from a well-known, 

reputable company,UPDATE it regularly, and USE it regularly.
 

1. New viruses come out every single day; an a-v program

 that hasn't been updated for several months will 

not provide much protection against current
viruses.

2. In addition to scanning for viruses on a regular basis,

 install an 'on access' scanner (included in most good

 a-v software packages)

 and configure it to start automatically each time you 

boot your system. This will protect your system by

 checking for viruses each time your computer 

 accesses an executable file.

3. Virus scan any new programs or other

 files that may contain executable code before you run or open them, no matter where they come from.  There
have been cases of commercially distributed floppy disks and CD-ROMs spreading virus infections. 

Virus Analysis

What is a computer virus?

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.

What kind of files can spread viruses?

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.

MALWARE eksploiting Messenger & social network

one of the most interesting developments in 2007 was the appearance of worms for instant messenger applications. Instant messenger applications have become very popular, but users rarely perceive them as potential infection vectors. Although IM-worms were detected prior to 2007, the start of the year brought a noticeable increase in this type of malware.
An analysis of the IM-worms detected so far this year provides some data on possible future trends.
As Table 1 shows, most new IM-worms target MSN Messenger, which is extremely popular in the United States, but almost never used in Russia. All the worms except for Atlex are written in Visual Basic.

These two facts taken together seem to indicate that IM-worms are at the initial stage of evolution. And the fact that the vast majority of the worms are written in Visual Basic demonstrates that most of the authors are fairly new to the virus writing scene and are relatively inexperienced programmers. VB is one of the easiest programming languages to master, but it's unsuitable for serious projects due to the large files and the relatively slow speed that results from this.