A hacker is someone who seeks and exploits weaknesses in a computer system or computer network. Hackers may be motivated by a multitude of reasons, such as profit, protest, challenge, enjoyment, or to evaluate those weaknesses to assist in removing them. Hacking practice can either be ethical or unethical. The activity where one breaks into the system but do not violate its security and credentials is called Ethical Hacking. Ethical hackers aim to bring into the administrator‘s notice and vulnerabilities in the system thereby, improvising the robustness and security. Thus term hacker does not mean criminal or bad guy. Actually, hackers are the persons with flawless programming skills and hands-on knowledge on both computer hardware and software.


On the other hand, there are people who can though break into systems, get access to secured accounts but their actions are usually unauthorized while they make a backdoor entry into your system. These people (often misinterpreted as hackers) are called as crackers. They try and crack passwords, security codes, etc

using various hacking software‘s which are already available. Such software‘s are meant to break the code using millions of trials programmed into it by other hackers.

Spoofing and Sniffing

These are two methods that hackers and criminals use to gain improper or illegal access to computer systems. Spoofing is becoming a common way to steal financial information through fake Web sites. The spoofed site is almost a mirror image of the real site and unless the unsuspecting user examines the spoof closely, he/she may inadvertently give out important personal and financial information.

Using a sniffer program is a popular way to ―grab‖ information as it passes over transmission lines regardless of whether they are hard-wired or wireless. It is almost impossible to detect and encryption is about the only way to safeguard against it.

Denial of Service Attacks

As companies and organizations expand their business to Web sites, they are opening another point of vulnerability through denial of service attacks. Using botnets to launch distributed denial of service attacks is becoming all too common. The hackers seem to enjoy attacking the most popular Web sites like Facebook and Twitter.


Denial of service attacks are at the core of some of the most serious forms of cyberwarfare being played out across the world between countries and governments. From Russia to Iran to South Korea, government networks are being targeted through these kinds of attacks. The use of botnets makes it very difficult to determine the origin of the attacks and pinpoint responsibility.