Virus: It is a program written to attack the normal operation of a Computer, normally which affects the programs associated with the Operating System or Device Driver. Usually it is transmitted through the executable files. Viruses can run only if the affected program is running. These are the most well-known internet security threat.
Worms: Similar to viruses but much more dangerous. They spread rapidly by accessing your email address book and automatically forwarding themselves to every address it has.
Trojan: It is a program written to make your Computer unprotected so that hackers can reach the data in your computer. Trojans are self-sufficient programs. These programs give unrestricted access of computers to attackers.
Spyware: It is a software that secretly collects user information while on the internet. Spyware can capture information like web browsing habits, email messages, usernames and passwords, and credit card information.
Adware: This program launches the advertisements in the form of pop ups. Usually the add words are based on the internet behavior of the user.
Spam: These are unwanted emails. In other words we can call them as unsolicited promotional mail.
Phishing: This is acquiring the personal and sensitive information of a person through official looking emails. Users of online banking and e-commerce websites are more prone to this attack.
Pharming: More advance method of Phishing in which the attackers create duplicate or similar looking website of other companies, to attract the customers and steal the data.
Cookies: These are program or information secretly stored in a computer especially the internet browser, which allows other users to monitor the internet activities of a person. These programs usually monitor the browsing nature of person so that the companies can create better marketing strategies.
Mail Bomb: An excessively large email (typically many thousands of messages) or one large message sent to a user’s email account. This is done to crash the system and prevent genuine messages from being received.
Scareware: A common trick cyber criminals use to make users think that their computer has become infected with malware to get them to purchase a fake application. Often the fake application that the user is tricked into purchasing is actually a malicious program which can disable real antivirus software and wreak havoc on a user’s machine.
Sniffers: A software program used to monitor the traffic in a network. The hackers may use the sniffed data to access important confidential data.
Rootkit: A program designed to hide objects such as processes, files or Windows registry entries (often including its own). This type of software is not malicious in itself, but is used by hackers to cover their tracks in previously compromised systems. There are types of malware that use rootkits to hide their presence on the system.