DoS
Denial of Service
Überlastungs- bzw. Verfügbarkeitsangriff
A DoS attack aims to make a service or system unavailable for legitimate users — through overload or the targeted exploitation of a vulnerability that crashes the system. It attacks availability, one of the three protection goals of information security. The distributed variant with many sources is called Distributed Denial of Service (DDoS).
History & facts. DoS differs fundamentally from attacks on confidentiality: it is not about stealing but about paralysing. This can happen via sheer load or via a targeted „hit“ — a single, cleverly formed request that triggers an error and crashes the service. Precisely in Operational Technology (OT) environments, where availability has top priority, an outage can directly endanger physical processes.
Outlook & recommendation. While the distributed variant (DDoS) requires above all filtering and absorption capacity, the vulnerability-based DoS can be prevented through patching and robust input validation. For critical services, redundancy, load limits and a rehearsed restart count. Since an availability outage at regulated entities can be reportable, DoS belongs in incident planning — not only as an IT but as a business risk.