Viruses, Worms and Trojan Horses (or simply referred to as Trojans) are all malicious programs that may and can cause harm to your computer. There are differences between the three.
A computer virus attaches to a file for an executable program and it has enough software code that allows it to replicate and attach to other files in the same PC when a person access the file or execute that program. A Worm is similar to the virus, but has the capability to move from PC to PC without any human intervention. Read more about Trojan horse below.
What is a Trojan?
A Trojan could appear as an useful program, which later turns to do damage for you. Usually a users is tricked into getting this software or utility installed. This could be anything from a beautiful game, a smiley creation application or even a presentation. The Trojan horse got its name from the old story where Greek soldiers who hid inside the wooden model of a horse, opened the gates of Troy to let the Greek army inside, helped to defeat the Trojans (people of Troy).
How does a Trojan work?
The Trojan normally works in a client server model. The part that get attached to your system could be the server part which opens up a tunnel for the client to connect (for the creator of the Trojan). Once the victim runs the server, the attacker uses a port to connect to that server. Normally a Trojan will hide itself in some unknown location and listens for any activity on a port. Most Trojans will mail the IP address of the victim to the attacker. And an attacker who gets this information can easily connect to the PC.
The initiation of a trojan is initially done by a uninformed victim. Once it is installed, the Tojan uses various methods to self start themselves. It could modify the registry to run itself or use different auto-starting methods like:-
- Explorer Starter
A trojan creater can add a host of facilities to help itself, these include
- Registry modification
- process monitoring tool
- FTP server
- Screenshot tool
- KeyLogger tool
The common modes of operation is to spread around using free software utilities, using CD or other writeable devices and eMail attachments.
So what can I do?
So how do you secure your PC against these Trojans? Be very careful when you install any unknown applications or download any unknown files through the internet. Well the least you can do is to have a personal firewall software like ZoneAlarm installed and also have a good Antivirus software installed. Wait for our upcoming article on the personal firewall applications. Mean while read more about PC Antivirus Protection from our last article.