The operation meant "tens of millions of pounds in potential fraud" against the British economy were avoided, the head of GCHQ said.
Hackers working for the UK's National Cyber Force (NCF) made hundreds of thousands of stolen credit cards worthless to criminals, according to the head of GCHQ, Sir Jeremy Fleming.
The operation meant "tens of millions of pounds in potential fraud" against the British economy were avoided, the spy chief told the Cyber UK conference in Newport.
Ministry of Defence and GCHQ operatives have "mounted operations to undermine [criminals'] networks, and prevent them from profiting from their crimes as well as denying them access to their cyber tools and malware," he said.
"Through the NCF, we are actively undermining the cybercriminals' assumption that they can act with impunity on the internet. We have disrupted criminals, making it clear that they are being observed, and going after their ability to profit from illegal activities," he said in a rare reference to operational activities.
Perhaps the most significant of the attacks on Ukraine took place on the same day that Russia's armed forces poured into the country, when wiper malware inside Viasat customers' satellite broadband routers was detonated,rendering them effectively useless.
The attack had considerable spillover, affecting 5,800 wind turbines in Germany operated by Enercon that used Viasat for remote monitoring and control.