History:
Trojans are the most harmful tool ever developed by the hackers, Back in 1998 the first Trojan named subseven was released and created a new history in the world of hackers.

It’s entry in the system :

Trojans actually comes from the file with dual extensions.
Dual extensions means one file is actually joined with another to form file which have executable program installed within it. When you click on that file nothing will happen or just command prompt will open and close in a second and get closed itself.

But when nothing happens there is always Trojan spy installed. The bug after installing try to send the files to the Trojan owner whenever you connect to the internet.
There are two parts of Trojan hacking and this hacking is done by anarchist hackers.

Explanation of the tool :
First part is a tool itself. Means the simple software by which you can play with the victim.
Second part is the bug, without which the tool can not be operated. If you wanted to hack someone by means of Trojan you need to send bug to his PC. And it can be done in many ways like by physical intrusion in the system or file transfer by the instant messenger or any another internet intrusion into the network or the system.

When you type in the IP address and port number of the victims PC , you’ll get direct connection to his PC And very easy access without even asking you password for connection.

After connecting , The hacker can play with your system in following different way.

1. He can recover all the passwords you have stored and also the user names too.
2. He can Open/Close Your CD ROM
3. He can log ON/OFF your PC.
4. He can open any web page in your system.
5. Can see all your files and folders.
6. Can operate and delete all your files and also able to format your PC.
7. Also he can chat with you with direct messenger.
8. Tilt your screen in any angle
9. He can hear what you saying and see you by your webcam ( condition is they should be ON)
10. He can play with your total system and can do many more things depends upon the knowledge and experience with hacker.

How to be prevented :

Always check the files you have downloaded .
Also check the extension of that file that is that what you want or not ?
Scan your file which is downloaded before opening it.
While chatting never disclose your original data.
Use firewalls which you can trust so that no bug can give out any information of yours.

For more detailed knowledge on Trojans please feel free to ask any questions here.
I will try to cover how Trojan works in my next post.

Thank you all for reading.