Trojans
- The name "Trojan Horse" derives itself from a page in Greek history.
- A Trojan horse is simply a computer program.
The program claims to do one thing (it may claim to be a game) but instead does damage when you run it (it may erase your hard disk). - Trojan horses have no way to replicate automatically.
- Examples:- Picture.exe,RIDBO,FIX2001,AOL4FREE
- These types of viruses were originally designed as a means of self expression by gifted programmers and did little more than to cause the system to lock up, behave abnormally in a specific way or perhaps cause loss of data on the user’s machine.
- Virtually every Trojan virus is comprised of two main parts:
- the "server"
- The server part is the part of the program that infects a victim's computer.
- the "client”
- The client part is the one that allows a hacker to manipulate data on the infected machine
How does a Trojan Affect Your Computer?
In order to gain access to a users computer, the victim has to be induced to install the Trojan himself.
The usual method is to offer a seemingly useful system enhancement or perhaps a free game that has the Trojan attached to it.
By installing it,the user also installs the Trojan.
Trojan Horse acts as a means of entering the victim’s computer undetected and then allowing a remote user unrestricted access to any data stored on the user's hard disk drive whenever he or she goes online.
In this way, the user gets burned and like the unfortunate citizens of Troy, may only discover that fact when it is too late.
Intruders scan the Internet for an infected user(technically speaking, an attacker sends request packets to all users of a specific Internet provider) using the client part of the virus.
Once an infected computer has been found (the server part of the virus that is located on infected machine replies to client part's request).
The attacker connects to that user's computer and creates a "link" between the two just like the one in an ordinary telephone conversation.
Once that has happened (this procedure may only take a few seconds), the intruder will be able to get unrestricted access to the user's computer and can do anything he likes with it.
The intruder becomes the master and the user the slave before disconnecting from the Internet, the user is helpless and has no means at his disposal to ward off an attack.
Intruders can monitor, administer and perform any action on your machine just as if they were sitting right in front of it.
There are no visible outward signs that anything untoward is happening other than perhaps unusual hard disk activity for no apparent reason.