- Home
- About Us & Project Introduction
- What Are "Cyber Security" and "Cyber Attack"?
- Why Does Cyber Security Matter?
- International and Local Cooperation on Cyber Attacks
- Simple Steps Towards Enhanced Cyber Security
- Educating the Public
- Video Reviews & Useful Resources
- Bibliography
- Acknowledgements
Denial of Service Attacks
In a denial of service attack (DOS attack), a hacker compromises a system and uses that system to attack the target computer, flooding it with more requests for services than the target can handle. In a distributed denial of service attack, hundreds of computers are compromised, loaded with DOS attack software and then remotely activated by the hacker.
In accessing web pages, your computer first sends a request to access the web page to the web site server. Then, the web site server allows you to access the web page. The server can answer a limited number of requests at a time. In the denial of service attack, a hacker will remotely control thousands of compromised computers (a.k.a. zombies) to send millions to request to the server. The server is unable to answer all the requests and breaks down. Hence, the web site becomes inaccessible to the public. For example, in response to the shutdown of the file-sharing website Megaupload, the hacking group Anonymous launched multiple DOS attacks to various parties related to the shutdown. The sites of the US Department of Justice, Federal Bureau of Investigation and Motion Picture Association of America were among the attacked. The Anonymous spread web links throughout the internet which would send a request to the attacked sites when clicked. This surge of requests caused the sites to be temporarily inaccessible to the internet users.
Also, the denial of service attack can be very personal. For example, without proper protection in the internet, your email account can been attacked by DOS attacks. Just like the web server, your email account has limited memory. You can see this at the bottom of every Gmail inbox page (picture below). A hacker can spam-send millions of high-volume emails to your email account until the memory is full. Then, you will be unable to receive any more emails.
In accessing web pages, your computer first sends a request to access the web page to the web site server. Then, the web site server allows you to access the web page. The server can answer a limited number of requests at a time. In the denial of service attack, a hacker will remotely control thousands of compromised computers (a.k.a. zombies) to send millions to request to the server. The server is unable to answer all the requests and breaks down. Hence, the web site becomes inaccessible to the public. For example, in response to the shutdown of the file-sharing website Megaupload, the hacking group Anonymous launched multiple DOS attacks to various parties related to the shutdown. The sites of the US Department of Justice, Federal Bureau of Investigation and Motion Picture Association of America were among the attacked. The Anonymous spread web links throughout the internet which would send a request to the attacked sites when clicked. This surge of requests caused the sites to be temporarily inaccessible to the internet users.
Also, the denial of service attack can be very personal. For example, without proper protection in the internet, your email account can been attacked by DOS attacks. Just like the web server, your email account has limited memory. You can see this at the bottom of every Gmail inbox page (picture below). A hacker can spam-send millions of high-volume emails to your email account until the memory is full. Then, you will be unable to receive any more emails.
Quick Reference
McDowell, M. (2009, November 4). National cyber alert system: understanding denial-of-service attack. Retrieved from http://www.us-cert.gov/cas/tips/ST04-015.html
Kelion, L. (2012, January 20). Hackers retaliate over megaupload website shutdown. BBC. Retreived from http://www.bbc.co.uk/news/technology-16646023
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McDowell, M. (2009, November 4). National cyber alert system: understanding denial-of-service attack. Retrieved from http://www.us-cert.gov/cas/tips/ST04-015.html
Kelion, L. (2012, January 20). Hackers retaliate over megaupload website shutdown. BBC. Retreived from http://www.bbc.co.uk/news/technology-16646023
Previous First Page