Denial-of-service attacks are designed to disrupt or degrade online services such as website, email and DNS services. To achieve this goal, adversaries may use a number of approaches to deny access to legitimate users of online services such as:
- using multiple computers to direct a large volume of unwanted network traffic at online services in an attempt to consume all available network bandwidth
- using multiple computers to direct tailored traffic at online services in an attempt to consume the processing resources of online services
- hijacking online services in an attempt to redirect legitimate users away from those services to other services that the adversary controls.
Although organisations cannot avoid being targeted by denial-of-service attacks, there are a number of measures that organisations can implement to prepare for and potentially reduce the impact if targeted. Preparing for denial-of-service attacks before they occur is by far the best strategy, it is very difficult to respond once they begin and efforts at this stage are unlikely to be effective.
While an organisation’s primary focus is likely to be preventing themselves from being a victim of denial-of-service attacks, all organisations can take steps to ensure that their own online services cannot be abused by an adversary to conduct denial-of-service attacks targeting others.