DDoS

Introduction   

      Distributed Denial of Service (DDoS) is a common cyber attack used to essentially take a server, website, or device offline. The resources that enable this kind of attack are, unfortunately, widely available and therefore it is also widely used. Small-scale attacks may require only very basic knowledge of computers, and botnets can be bought for relatively small amounts of money on online "blackmarkets". Although this is illegal, these attacks are extremely difficult to trace as the information is sent through multiple computers (hence Distributed) and can be hard to discern from regular network activity.

How Does it Work?

     The source of the attack begins by creating botnets -- a network of computers that act as agents of the attack, not necessarily owned by the source, which can be taken over and controlled remotely without the device owners knowledge. Once established, the botnets simultaneously attack the target in one of several ways; sending more connection requests than a server can handle or sending a bunch of random data to use up the targets bandwidth (how much data can be transferred from point A to point B in a set amount of time). This renders the targets' connection slow or completely cut off for however long the attack is active.

Prevention

    By installing proper antivirus software and/or using a firewall, you can prevent your computer from being used as an agent of an attack. One technique that popular sites and services might use to lower the chances of being subjected to an attack is bandwidth oversubscription, which makes it more difficult for the source to grow their botnet network large enough to successfully overwhelm the target. DDoS mitigation is also common, and attempts to monitor the amount of information being sent/received from each source and tunes out the "noise" that is the random data sent in some attacks. Overall, you probably won't be a victim of a DDoS attack unless you have a controversial website or piss off the wrong guy in a PvP match.

There are so many more components to and forms of DDoS attacks -- if you're interested, check out these sources!

http://www.digitalattackmap.com/understanding-ddos/
http://www.webopedia.com/TERM/D/DDoS_attack.html
https://www.us-cert.gov/ncas/tips/ST04-015
http://security.stackexchange.com/questions/73369/how-do-major-sites-prevent-ddos