how do i start writing a antivirus program?

[J radolf]

Hi guys

where do i start from?

i mean there may be several programming languages used for this?

can anyone tell me "HELLO WORLD" type of example or links related to this?

it will be helfull for my career.

Thanks
Radolf

[Joachim Rohde]

I still have some sources I wrote ages ago (1998), to search the hard disk for certain viruses (namely Tai-Pan, NPOX, Parity Boot B and Delwin) and to remove them. The sources can be found under http://www.joachimrohde.com/cms/xoops/modules/mydownloads/visit.php?cid=2&lid=12 if you want to have a look.
They are written in Pascal and Assembly, comments are only available in German, but they are out-dated anyway.
When I wrote this little piece of code the book "Virus: Detection and Elimination" (http://www.amazon.com/Virus-Detection-Elimination-Rune-Skardhamar/dp/012647690X/ref=sr_1_1?ie=UTF8&s=books&qid=1252077958&sr=8-1) was quite handy. It's full of (assembly) sources. There are a few other technical books which are newer, but I haven't read any of them, so I can't make any suggestions.

I guess you'll need a good understanding of reverse engineering (and thus of machine code & your decompiler) for analyzing the malware (The book "Know your enemy" comes in handy here). Writing the part to detect and remove the malware, will be peanuts.