Lloyds Banking Group fought off three-day cyber attack
Lloyds Banking Group has fended off a three-day-long cyber attack designed to overwhelm the bank's systems and disrupt its digital services.
Cyber criminals made millions of fake requests intermittently between Wednesday January 11 and Friday January 13, which stopped some customers from using their online accounts.
The series of distributed denial of service (DDos) assaults came from overseas servers and affected the Lloyds, Halifax and Bank of Scotland brands.
In a game of cat and mouse, Lloyds defended its systems using a "geoblocker" that stops all traffic coming to its website from a particular country, but can also prevent customers in that region from accessing their accounts.
While some customers could not log into their digital accounts or experienced a slow online service, the attack did not result in any customer bank accounts being hacked.
A spokesman for Lloyds Banking Group said: "We experienced intermittent service issues with internet banking between Wednesday morning and Friday afternoon the week before last and are sorry for any inconvenience caused.
"We had a normal service in place for the vast majority of this period and only a small number of customers experienced problems. In most cases if customers attempted another log-in they were able to access their accounts.
"We will not speculate on the cause of these intermittent issues."
Lloyds faced a flurry of complaints from customers on social media during the attack, but did not reveal the problems it was facing at the time.
It is the latest high-profile cyber assault to hit Britain's banking industry since Tesco Bank had to freeze online transactions for customers after falling foul of a hack in November.
Tesco Bank paid out an estimated £2.5 million to 9,000 customers following the breach, with the Financial Conduct Authority chief executive Andrew Bailey describing it as "unprecedented".
A spokesperson for the British Bankers' Association (BBA) said: "Banks are constantly vigilant to the changing security threats online and work closely with law enforcement and government and regulators to help protect customers and make them safe.
"Banks are also continually developing sophisticated systems to ensure customers are as secure as possible."
The National Cyber Security Centre (NCSC) - part of Government Communication Headquarters (GCHQ) - is understood to be working with Lloyds on the attack.
A spokesman for the NCSC said: "As part of normal business practice, the NCSC and financial authorities work with firms to provide guidance and support if needed.
"The NCSC serves as a bridge between industry and government to promote the highest standard of information security, including offering help on managing incidents."