Mar 27, 2013

How can a DDoS attack on a single company slow down the entire internet?

The news wires have been reporting the largest DDoS attack in history is taking place today against a company called Spamhaus. I haven't noticed much of an impact, but the news reports suggest that the effect is being felt by companies including Netflix. How can a single attack have such a wide impact?

Here's a good overview of DDoS attacks.

Denial-of-service attack

"In computing, a denial-of-service attack (DoS attack) or distributed denial-of-service attack (DDoS attack) is an attempt to make a machine or network resource unavailable to its intended users. Although the means to carry out, motives for, and targets of a DoS attack may vary, it generally consists of the efforts of one or more people to temporarily or indefinitely interrupt or suspend services of a host connected to the Internet.
Perpetrators of DoS attacks typically target sites or services hosted on high-profile web servers such as banks, credit card payment gateways, and even root nameservers. This technique has now seen extensive use in certain games, used by server owners, or disgruntled competitors on games such as Minecraft and League of Legends. The term is generally used relating to computer networks, but is not limited to this field; for example, it is also used in reference to CPU resource management.[1]

One common method of attack involves saturating the target machine with external communications requests, so much so that it cannot respond to legitimate traffic, or responds so slowly as to be rendered essentially unavailable. Such attacks usually lead to a server overload. In general terms, DoS attacks are implemented by either forcing the targeted computer(s) to reset, or consuming its resources so that it can no longer provide its intended service or obstructing the communication media between the intended users and the victim so that they can no longer communicate adequately.

Denial-of-service attacks are considered violations of the IAB's Internet proper use policy, and also violate the acceptable use policies of virtually all Internet service providers. They also commonly constitute violations of the laws of individual nations."

And cue conspiracy theories from The Guardian in 3.....2......1........conspiracy theory!


It's because the attackers worked their way upstream from the original target, as this ITworld article explains:


The attackers ultimately targeted Tier 1 providers, which operate the networks at the core of the Internet, and Internet Exchanges (IX), critical nodes located around the world that connect large networks like those of Google, Facebook, Yahoo and pretty much every major Internet company.



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