British businesses are being urged to step up their vigilance against a China-linked hacking ploy that uses everyday devices for espionage. The UK’s National Cyber Security Centre (NCSC) and agencies in nine other countries have warned of persistent attempts by Beijing-backed groups to hack equipment such as wifi routers to launch cyber-attacks. Known as “covert networks” or “botnets”, they typically target vulnerable equipment – for instance devices that have not had a software update or are old – as a base for staging activities such as surveillance and data theft. The NCSC said the technique was used by the majority of China-linked hackers. Richard Horne, the centre’s chief executive, said on Wednesday that China’s intelligence and military agencies had an “eye-watering level of sophistication in their cyber-operations”.…