G 0.40 Denial of Services (Denial of Service)

There are a variety of different attack forms aimed at preventing the intended use of certain services, functions, or devices. The umbrella term for such attacks is “Denial of Service” (abbreviated as “DoS”). The term “DoS attack” is also frequently used.

Such attacks can come from, among others, disgruntled employees, customers, or competing companies. Extortion or political motives can also be reasons for such attacks. The targets of the attacks can be business-critical assets of all kinds. Typical manifestations of DoS attacks are

• Disruptions of business processes, for example through flooding the order intake with erroneous orders,
• Impairments of infrastructure, for example through blocking the doors of the institution,
• Causing IT failures by, for example, deliberately overloading a server’s services on the network.

This type of attack is often associated with distributed resources, in that these resources are strained so heavily that they are no longer available to the actual users. In IT-based attacks, for example, the following resources can be artificially made scarce: processes, CPU time, memory, disk space, transmission capacity.

Example:

• In spring 2007, strong DoS attacks took place over a prolonged period against numerous Internet offers in Estonia. This resulted in considerable impairments in Estonia when using information offers and services on the Internet.