Ddos – Danish municipalities and KL

On Monday 9 December 2024, DDoS attacks took down the websites of up to 20 Danish municipalities, along with the website of KL (Kommunernes Landsforening). Aarhus, Esbjerg, Frederiksberg, Vejle, Albertslund, Guldborgsund and Frederikshavn were among those affected. The attacks continued for several days.

NoName057(16) claimed responsibility and tied it explicitly to Denmark's delivery of F-16 aircraft to Ukraine. Center for Cybersikkerhed observed DDoS attempts against Danish websites throughout December 2024 and assessed the effect as limited but disruptive — citizen-facing information and services were unreachable, but nothing was breached behind the websites.

KL subsequently argued publicly that municipalities could have been warned in advance had they been part of the national cyber defence arrangements, which is the policy question this incident is mostly remembered for.

This entry is one instance of a recurring pattern rather than an isolated event: comparable waves hit Danish authorities in February 2024 (Domstolsstyrelsen, Rejsekort, Udenrigsministeriet, several municipalities) and again around the November 2025 municipal elections.

• Center for Cybersikkerhed — Opfølgning på DDoS-angreb mod danske hjemmesider
• DR — Angreb på kommuners hjemmesider fortsætter på fjerde dag
• Danske Kommuner — KL: Vi kunne være blevet varslet om hackerangreb
• TV 2 — Hackere angriber flere danske instanser (februar 2024)
• TV 2 — Massivt prorussisk cyberangreb har klart formål, siger IT-ekspert