The threat of online security: various ways hacker hack to get information

Do you know what is hacker and cracker? "Hacker" is recognize as a negative term by most of the people. Actually, "hacker" help create programs and applications or improve computer security. However, anyone using his or her skills maliciously is not a hacker but a cracker. Crackers infiltrate systems and cause mischief or worse. Malicious hackers use programs to:

1. Hack passwords: Malicious hackers try to hack someone's password from guesses to simple algorithms that generate combination of letters, numbers and symbols. There is another way which named brute force attack which use trial and error method to hack password. In other way, malicious hacker use a dictionary attack to hack password, which means malicious hacker use a program that inserts common words into password fields.
2. Hacker infect a computer or system with a virus: A computer viruses are programs designed to duplicate themselves and cause problems ranging from crashing a computer to wiping out everything on a system's hard drive. The computer viruses sent out by malicious hacker via email, instant meessages, web sites with downloadable content or peer-to-peer networks to the potential victims.
3. Log keystrokes: There are some programs allow malicious hackers to review every keystroke a computer user makes. Once the program installed on a victim's computer, the programs record each keystroke, giving the hacker everything he needds to infiltrate a system or even steal someone's identity or information.
4. Gain backdoor access: Malicious hackers create programs that search for unprotected pathways into network systems and computers. In the early days of the internet, most of the computer systems had limited security and making possible for a malicious hacker to find a pathway into the system without a username and password. Use Trojon horse to infect a computer system is another way that used by malicious hacker to gain backdoor access.
5. Create zombie computers: A zombie computer, or named bot, is a computer that a hacker can use to send spam or commit distributed denial of service (DDos) attacks. After a victim executes seemingly innocent code, a connection opens between victim's computer and the hacker's system. The malicious hacker can secretly control the victim's computer using it to commit crimes or spread spam.
6. Spy on e-mail: Malicious hackers have created code that lets them intercept and read e-mail messages. Today, most e-mail programs use encryption formulas as complex that even if a hacker intercepts the message, he won't be able to read it.