How virus works

Hi,
I want to study abt how virus working.. like how it get into the memory and attaching itself to other files and replication part.

I gone through some of the articles in web but I'm able to find those articles are based on DOS. I knew writing memory resident prg and interrupt prg in DOS.
In dos there is no protection in memory and we can access anywhere in the memory. But how the virus working in win 2k/xp ?
I'm half the way studying winnt internals but i'm not able to match with programming.
Is there any good turtorial will explain with realted to win2k.

Dont suggest me any books.. finacially i am not in the position to buy any books.....If any online e-books/articles/tutorials plz let me know.
-lok.

well firstly the ONLY thing that defines a virus is its ability to replicate and spread. the malicious intent comes from what the program actually does.

So from that, a virus is a 'self-copying' program that does as its told. :p

from you question, you want to know how to program, not nessicarily a virus, but programming in general... can i suggest http://www.programmingtutorials.com/

from there you should pickup on the languages you like, so google up so other tuts :D


CTO

Little blackbook of computer viruses: http://vx.netlux.org/lib/vml00.html
Giant blackbook of computer viruses: http://vx.netlux.org/lib/vml01.html

You might want to check out the whole site as wel: http://vx.netlux.org/lib/?lang=EN

i think i got a solution for that! and not only that if u want to know about working of anything you can just visit the website:


www.howstuffworks.com

happy surfing

Thanks for ur suggestions,
http://vx.netlux.org/lib/?lang=EN helps lot to understand the basics.

In my four hrs study, If we want to working of basics of virus via program

we need to do is,
Study the exe* file format ( *any file format virus infects)
study asm it will help how commands executed low level. It will help us
How the virus code get into the other file without disturbing the functionality of the original file.
Most important OS internels help us how process executed and the memory protection techniques... etc.

-lok.