Threats

5Denial of Service and Availability

Resources are always finite and sometimes constrained. Denial-of-service attacks threaten availability by consuming some resource, slowing, crashing, or freezing things. Freezing Han Solo in carbonite was easy—heck, Luke Skywalker was nearly frozen just because he went outside on the ice planet Hoth. It's freezing in a way that allows recovery that requires cleverness. As an aside, Han was supposedly frozen to test the system, and it's not clear why Darth Vader doesn't demand that he be fully thawed out. The goal of full-cycle testing is especially important for denial of service.

Brute force is the easiest form of denial-of-service attacks. But there are plenty of clever denial-of-service attacks that use knowledge of (or assumptions about) what's expensive for a specific target. Denial of service is often focused on an organization, but not always. These attacks are used to disconnect opponents from games, to “split” IRC networks so someone can be given operator privileges), and for many other reasons.

Denial of service is often abbreviated DoS or DOS. (The latter is less confusing now that no one uses Microsoft's Disk Operating System.) These attacks often come from many small systems, leading to the acronym DDoS, for distributed denial of service.

Like an Ewok, each attacker can be smaller and weaker than its target, but with sheer numbers can overwhelm a well-defended target. This property is shared with many distributed denial-of-service ...