Dentsu has said it identified “unusual activity” on its Merkle network on 27 October, and confirmed “certain files” have been taken containing information about clients, suppliers, current and former employees.
In an email to staff seen by Decision Marketing, the company suggested the compromised information includes bank and payroll details, salary, National Insurance numbers and personal contact information.
In response to the attack, Dentus has said it has taken some of its systems offline, engaged third-party cyber incident response firms, and notified law enforcement.
However, a company spokesperson has since confirmed: “We have brought systems back online and we are fully operational.”
The company has also started informing affected individuals in accordance with applicable laws; however, it is unclear at this stage how many people have been affected.
For affected employees, the company is offering a year of credit and dark-web monitoring services through Experian Identity Plus.
Dentsu has not been able to offer any more information at this point on who is responsible for the attack.
This attack follows a series of cyber attacks in the UK in the past year, for instance, M&S experienced a ransomware attack in April, which impacted operations until July, and has reduced profits for the current year by around £300m.
The Chancellor, Rachel Reeves, recently suggested to ITV News that Russia are behind some of the cyber attacks the UK has suffered in recent months.
