I dunno if this helps or not....

Theres a difference between a virus and a trojan. Viruses (aka worms) are built to be downloaded, replicate, and then infect somebody else. Trojans are made to only infect the person that was infected (ie, they dont spread).

Generally, trojans are made to advertise a product, ususally bombarding ya with annoying popups, etc. Viruses on the other hand are sometimes gravitated toward creating damage, not just advertisement.

Sorry if this makes no sense

Thanks.

I would like to further explain this response:

A trojan is a program that allows a portal into a victim's computer through a seemingly innocent program. Once this portal is open a person could use that opening to control the users computer or advertise through pop ups and so forth.

There are programs out there that combine the abilities of trojans(being able to open ports on a computer and sit waiting for a connection) and the abilities of a virus(deploy, multiply, deploy on nearby computers, repeat).

The most sophisticated of these programs are written to attack vulnerabilities that are discovered in windows which require NO user error to open. This could include any number of things such as the DCOM exploits seen 2-3 years ago, and so forth.

That is why a firewall should always be used in conjunction with an antivirus, because most antivirus programs wont pick up a simple server program such as netcat which enables command line control of the entire computer.

Err..for the most part. Not all trojans allow open portals into your computers. Some open portals just to other automized downloaders (hence the name, "downloader trojan") Most trojans, however, just slow down the computer overall.

There are trojans that allow access to the computer, (theryre called Remote Access Trojans, aka RATs), but they they're prettty rare.

Thanks.

thanx for replies....but i just wanna ask are viruses,worms and trojan horses type of malicious codes or malicious codes are different thing....i think they r the types of malicious codes....i read on many places i've to deliver presentation on it that why i want to make it confirm... please clarify it

Basically, malicious code is code which is intended to do something which the user would not knowingly run. Viruses, Trojans, Worms, etc are pretty much Malicious Code by definition.

thanx alot.....