Tesco Bank cyber attack involved guesswork, study claims

Academics say working out card number, expiry date and security code of Visa card takes 'as little as six seconds'

A team of academics claims an unsophisticated type of cyber attack that exploits "flaws" in the Visa card payment system was probably used to defraud Tesco Bank customers of 2.5m last month.

Related: Cyber attack: hackers 'weaponised' everyday devices with malware to mount assault