Editing Denial-of-service attack (section)

==Unintentional denial-of-service==
An unintentional denial-of-service can occur when a system ends up denied, not due to a deliberate attack by a single individual or group of individuals, but simply due to a sudden enormous spike in popularity. This can happen when an extremely popular website posts a prominent link to a second, less well-prepared site, for example, as part of a news story. The result is that a significant proportion of the primary site's regular users{{spaced ndash}}potentially hundreds of thousands of people{{spaced ndash}}click that link in the space of a few hours, having the same effect on the target website as a DDoS attack. A VIPDoS is the same, but specifically when the link was posted by a celebrity. When [[Death of Michael Jackson|Michael Jackson died]] in 2009, websites such as Google and Twitter slowed down or even crashed.<ref>{{cite news| url=http://news.bbc.co.uk/1/hi/8120324.stm | work=BBC News | first=Maggie | last=Shiels | title=Web slows after Jackson's death | date=2009-06-26}}</ref> Many sites' servers thought the requests were from a virus or spyware trying to cause a denial-of-service attack, warning users that their queries looked like "automated requests from a [[computer virus]] or spyware application".<ref>{{cite web|date=October 20, 2009|title=Unexpected Search Results|url=http://productforums.google.com/forum/?#!category-topic/websearch/unexpected-search-results/uFcXXixhiBw|access-date=2012-02-11|work=Google Product Forums › Google Search Forum}}{{dead link|date=April 2025}}</ref>

News sites and link sites{{spaced ndash}}sites whose primary function is to provide links to interesting content elsewhere on the Internet{{spaced ndash}}are most likely to cause this phenomenon. The canonical example is the [[Slashdot effect]] when receiving traffic from [[Slashdot]]. It is also known as "the [[Reddit]] hug of death"<ref>{{cite web |url=https://medium.com/codingame/story-of-a-reddit-hug-of-death-and-lessons-learned-3565bb8a6793 |title=Story of a Reddit Hug of Death and Lessons Learned |date=16 November 2017 |access-date=2024-09-24}}</ref> and "the [[Digg]] effect".<ref>{{cite web |url=http://socialkeith.com/the-digg-effect-v4/ |title=The Digg Effect v4 |publisher=Social Keith |access-date=October 20, 2010 |first1=Keith |last1=Plocek |archive-url=https://web.archive.org/web/20101022060115/http://socialkeith.com/the-digg-effect-v4/ |archive-date=October 22, 2010 |url-status=dead }}</ref>

Similar unintentional denial-of-service can also occur via other media, e.g. when a URL is mentioned on television. In March 2014, after [[Malaysia Airlines Flight 370]] went missing, [[DigitalGlobe]] launched a [[crowdsourcing]] service on which users could help search for the missing jet in satellite images. The response overwhelmed the company's servers.<ref>{{cite web|url=http://wnmufm.org/post/people-overload-website-hoping-help-search-missing-jet|title=People Overload Website, Hoping To Help Search For Missing Jet|author=Bill Chappell|publisher=NPR|date=12 March 2014|access-date=4 February 2016}}</ref> An unintentional denial-of-service may also result from a prescheduled event created by the website itself, as was the case of the [[Census in Australia]] in 2016.<ref>{{cite web|url=https://delimiter.com.au/2016/08/19/experts-cast-doubt-census-ddos-claims/|title=Experts cast doubt on Census DDoS claims|date=19 August 2016|access-date=31 January 2018|last=Palmer|first=Daniel|publisher=Delimiter}}</ref>

Legal action has been taken in at least one such case. In 2006, [[Universal Tube & Rollform Equipment|Universal Tube & Rollform Equipment Corporation]] sued [[YouTube]]: massive numbers of would-be YouTube.com users accidentally typed the tube company's URL, utube.com. As a result, the tube company ended up having to spend large amounts of money on upgrading its bandwidth.<ref>{{cite news |title=YouTube sued by sound-alike site |work=BBC News |date=2006-11-02 |url=http://news.bbc.co.uk/2/hi/business/6108502.stm }}</ref> The company appears to have taken advantage of the situation, with utube.com now containing ads and receiving advertisement revenue. 

Routers have also been known to create unintentional DoS attacks, as both [[D-Link]] and [[Netgear]] routers have [[NTP server misuse and abuse|overloaded NTP servers]] by flooding them without respecting the restrictions of client types or geographical limitations.