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What are DoS and DDoS attacks?



What are DoS and DDoS attacks?


If your favourite website is down, there’s a chance it’s suffering a Denial of Service (DoS) attack. This is more likely if the site is an online shop, a bookie or another site that relies financially on being online at all times.



Enemy at the gates

A DoS attack tries to make a web resource unavailable to its users by flooding the target URL with more requests than the server can handle. That means that during the attack period, regular traffic on the website will be either slowed down or completely interrupted.


A Distributed Denial of Service (DDoS) attack is a DoS attack that comes from more than one source at the same time. A DDoS attack is typically generated using thousands (potentially hundreds of thousands) of unsuspecting zombie machines. The machines used in such attacks are collectively known as “botnets” and will have previously been infected with malicious software, so they can be remotely controlled by the attacker. According to research, tens of millions of computers are likely to be infected with botnet programs worldwide.


Cybercriminals use DoS attacks to extort money from companies that rely on their websites being accessible. But there have also been examples of legitimate businesses having paid underground elements of the Internet to help them cripple rival websites. In addition, cybercriminals combine DoS attacks and phishing to target online bank customers. They use a DoS attack to take down the bank's website and then send out phishing e-mails to direct customers to a fake emergency site instead.


DoS attacks have proven to be very profitable and are taking over the Internet. The Network Infrastructure Security Report points out that DDoS attacks have increased by 1000 per cent since 2005. 2010's biggest attack doubled in scale compared to 2009, with one attack in particular bombarding its target at 100 gigabits per second.



A new type of warfare

A WikiLeaks story from 2010 has redefined DDoS attacks as a legitimate form of protest. Computing expert Richard Stallman has gone on record saying DDoS attacks are "the Internet equivalent of a mass demonstration." Stallman defines such "demonstrations" as being separate from hacking or cracking, and compares them with harmless demonstrations that temporarily closed down several British stores recently, in order to highlight corporate tax evasion.


However, you should know that DDoS attacks are illegal under the Computer Fraud and Abuse Act and can lead to prison time.


Furthermore, new factors that arise every day are making DDoS attacks a big concern, especially with the growth of high-speed fibre optic Internet connections and mobile computing devices.

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