NCSC issues hacktivist warning

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Organisations, particularly local government authorities and operators of critical national infrastructure, are being encouraged to review their defences and improve their cyber resilience by preparing and being able to respond to denial of service (DoS) attacks. 

Although DoS attacks are typically low in sophistication, a successful attack can disrupt entire systems, costing organisations significant time, money, and operational resilience by having to analyse, defend against, and recover from them. 

The alert notes that the ongoing attacks by Russian-aligned hacktivist groups are driven by ideology, over perceived Western support for Ukraine, rather than financial gain, and they operate outside the direct control of the state.  

In December 2025, alongside international partners, the NCSC co-sealed an advisory which called out pro-Russian hacktivists groups for targeting government and private sector entities in NATO member states and other European countries that are seen as standing in opposition to Russia’s geopolitical ambitions. 

NCSC Director of National Resilience, Jonathon Ellison said: “We continue to see Russian-aligned hacktivist groups targeting UK organisations and although denial-of-service attacks may be technically simple, their impact can be significant. 

“By overwhelming important websites and online systems, these attacks can prevent people from accessing the essential services they depend on every day. 

“All organisations, especially those identified in today’s alert, are urged to act now by reviewing and implementing the NCSC’s freely available guidance to protect against DoS attacks and other cyber threats.”

The NCSC has persistently called out malicious cyber activity from Russia and its supporters. In 2023, the NCSC alerted organisations to the emergent risk posed by state-aligned adversaries following the Russian invasion of Ukraine. 

Organisations are also encouraged to engage with the NCSC’s heightened cyber threat collection.