You must have seen that any attempt to login to any server is logged and if the hacker is unable to clean the log, he can be very easily traced by the administrator of the server. The reason that if hacker is unable to clean the log sounds silly but he can also be caught if at the time of his access, the administrator is also logged in. Now its not possible to use a cybercafe everytime he hacks something. lol. So how does he protect himself from getting caught? This is something that is teached before teaching how to hack Servers on the World Wide Web.
Make sure you read How a hacker can gain access to your PC?
Now, that a hacker has gain access to your PC. He uses your PC to hack others. So that even someone is able to trace him back he can get away with this easily and you are caught. Many times you don’t get caught because the hacker don’t want to ruin a already establish workstation. Hackers are pretty smart. But sometimes the administrators are also smart. lol. They can trace back from where the attack was carried out and there they got you. You won’t have the slightest hint of what has really happened unless FBI tells you so and your fault was just that you didn’t took proper measures for your security because of which you pose a security threat for others.
Its time to tighten your security. Isn’t it? What say?