Denial Of Service Attacks (DoS)

In DoS attacks, the attacker attempts to overload or shut down a system so that users can no longer access it. Most frequently web servers are targetted in order to make websites unavailable. The main target is not to steal or compromise data but to interrupt a web service which can prove costly for some organisations and companies.

These types of attacks involve sending more traffic to a system than it can handle. This can be performed by sending oversized data packets, sending email attachments which longer names than supported by mail programs, sending IP ping messages that seem to originate from the victim computer to a large number of computers (victim is flooded with responses afterwards).

A Distructed Denial of Service attack (DDoS) attack uses a large number of computers (usually part of a zombie network - computers that are compromised and controlled by hackers by using a virus or trojan) to launch the attack.

Phising

Phising is a method of attempting to obtain information such as usernames, passwords and credit card details by sending emails appearing to come from a reputable source (such as a bank). These emails usually include what is supposed to be the organisations's - source's website, however when you click on it you are tranferred to a replica of the website where any details you enter from usernames to account numbers are used by hackers.

The fake replicated website has the same look and feel and is almost identical to the legimate one or the backgroup page link displays the genuine web site but a pop up superimposes and details you enter there are being stolen.

Phising incidents are contantly increasing. Users should be very careful when receiving generic salutations in email (Dear Customer....) and wary about following links sent to you in emails.

Anti-spam software can block many phising-related emails and some of them can detect phising content on web pages and provide a toolbar showing the real domain for the website you are following the link to.

Worms

A computer worm is a program which self-replicates and uses a computer network to send copies of it self to other networked computers, with or without user intervention. Worms differ from viruses in that they can propagate themselves instead of using a carrier program or file.

Worms almost always cause some harm to the network (e.g. consuming bandwidth, encrypting data on a user's computer, use infected computers to launch DoS attacks from), whereas viruses almost always corrupt or modify files on a targeted computer. Many worms open a “back door” on the computer, allowing hackers to take control of it. Such computers can then be used to send spam mail. Operating system vendors frequently issue patches to fix security faults in their software.