The most common threats that are faced on Internet are:
Malicious code is one that causes damage to a computer or system. Malicious code can either activate itself or be like a virus requiring a user to perform an action, such as clicking on something or opening an email attachment. It can also affect a network, send messaged through email and steal information or cause even more damage by deleting files.
A sniffer is a program that uses Internet to record information that passes through a computer or router in transit from sender to receiver. Using a sniffer program is like tapping the telephone wire and recording the conversation. Sniffer programs can read e-mail messages, user login, password and credit card numbers.
Denial of service attack
A Denial-of-Service (DoS) attack is an attack used to shut down a machine or network, making it inaccessible to tie intended users. By targeting the user’s computer and its network connection, or the sites which the user tries to access, an attacker may be able to prevent the user from accessing email, websites, and online accounts like banking or other services that relay on the affected computer. The users are flooded with hundreds and thousands of messages that create traffic problem on the network.
Cyber vandalism is the electronic defacing of an existing website page. An attacker replaces the website’s original content with his / her own content. It is an example of integrity violation. It is the electronic equivalent of destroying property or placing graffiti on someone’s photograph. Today, there are so many cases of cyber vandalism where the business content is replaced by offensive material.
Spoofing or masquerading is pretending to be someone you are not, or representing a website as authentic when it is actually a fake. It is technique where the attacker tries to assume the identity of another person or system for transacting the victim site. For example, an attacker can create a fake website as www.gswan.co.in and substitute his IP address for the real website IP address. All the user’s visiting to the real site will then be redirected to the fake website.