British Airways (BA) has revealed all its staff who are paid in the UK have been caught up in a cyber incident that has exposed personal data including bank and contact details to hackers.

It emerged last week that a so-called zero-day vulnerability – a flaw – in the file transfer system MOVEit, produced by Progress Software, had been exploited by cyber criminals.

It had allowed the hackers to access information on a range of global companies using MOVEit Transfer.

Thousands of firms are understood to be affected.

UK-based payroll provider Zellis confirmed on Monday that eight of its clients were among them.

It did not name the organisations.

BA, however, confirmed it had been caught up in the affair.

The airline employs 34,000 people in the UK.

Boots said it had been affected too.

The compromised information includes contact details, national insurance numbers and bank details.

A BA Spokesman said: “We have been informed that we are one of the companies impacted by Zellis’ cybersecurity incident which occurred via one of their third-party suppliers called MOVEit.

“Zellis provides payroll support services to hundreds of companies in the UK, of which we are one.

“This incident happened because of a new and previously unknown vulnerability in a widely used MOVEit file transfer tool. We have notified those colleagues whose personal information has been compromised to provide support and advice.”

A Boots spokesperson said: “A global data vulnerability, which affected a third-party software used by one of our payroll providers, included some of our team members’ personal details.

“Our provider assured us that immediate steps were taken to disable the server, and as a priority we have made our team members aware.”

Zellis said in its own statement: “A large number of companies around the world have been affected by a zero-day vulnerability in Progress Software’s MOVEit Transfer product.

“We can confirm that a small number of our customers have been impacted by this global issue and we are actively working to support them.

“All Zellis-owned software is unaffected and there are no associated incidents or compromises to any other part of our IT estate.

“Once we became aware of this incident we took immediate action, disconnecting the server that utilises MOVEit software and engaging an expert external security incident response team to assist with forensic analysis and ongoing monitoring.”

Comments by Emma Whitmore, Group Vice President, EMEA at Edgio: “Cyberattacks can happen at any time, often without warning. British Airways and Boots’ breach demonstrates that no organisation is safe from the threat cybercriminals pose and adequate security solutions are an absolute necessity in today’s climate.

“Organisations need full 360-degree visibility into all traffic across their network to detect security exploits – and they need the right solutions in place to help them respond quickly. They must be aware of their current security posture – identifying attack vectors and employing security solutions to resolve any vulnerabilities or other risks to the business. This will include understanding security best practices and the latest standards and regulations related to their online business.

“With the increase in exploits, organisations must also ensure their security solution provides the ability to make critical decisions fast to prevent any downtime. With the correct approach to cybersecurity, brands can ensure their services run smoothly.”