Denial of service (DoS) and Distributed Denial of Service (DDoS) attacks
Introduction
A denial of service (DoS) attack is where an attempt is made to make a network, a computer on a network or a resource on a network such as a website unavailable for use by any of the authorised users. An attack may come from one source, or it may come from thousands of sources, known as a DDoS attack, or Distributed Denial of Service attack.
Why are DoS attacks a problem?
DoS attacks stop an individual, a business, an organisation or a Government carrying out its activities. It can also act as a smokescreen for other illegal activities, such as injecting malware into a system.
How does a DoS work?
When an attacker uses a single internet connection to launch an attack, they attempt to flood the target victim with thousands upon thousands of fake requests. The target tries to respond to each request it receives, but quickly becomes overloaded and slows right down. The same thing happens in a DDoS attack, except this time, the attack is coordinated from many different sources, increasing the number of fake requests considerably.
Who carries out a DoS attack?
These kinds of attacks are often carried out by people who strongly disagree with what an individual, a business, an organisation or a Government is doing and so try to close them down temporarily to express their displeasure. The anarchic group Anonymous is probably the most famous organisation which uses this tactic to make its point. They are also typically carried out by bored teenagers and people in their early twnties, who use freely available DoS scripts available on the Internet to cause havoc.