The cooperative has apologized after Hacker has accessed and extracted the personal data of the members such as names and contact details.
The retail company announced on Friday that it was experiencing “persistent malicious attempts” to access its systems because it already switched off parts of his IT systems at the beginning of this week.
After other retailers Harrods and Marks & Spencer were also affected by cyber attacks. The latter continued to deal with the failure of a ransomware attack, in which the company has not been able to edit online orders since last Friday.
The National Crime Agency (NCA) said that it examined the attacks individually, but “careful that they may be connected”.
A co-op spokesman said: “As a result of the ongoing forensic studies, we now know that the hackers were able to access data from one of our systems and extract them.
“The access data included information about a significant number of our current and previous members.
“These data includes personal data from co-op group members such as names and contact details and contain no passwords, banking or credit card data, transactions or information from members who relate to the products or services of members or customers with the KOOP group.
“We have implemented measures to ensure that we prevent unauthorized access to our systems and at the same time minimize the disturbance of our members, customers, colleagues and partners.
“We appreciate that our members have set their confidence in our cooperative in providing information.
The company said that its back office and call center services were affected, but the more than 2,000 grocery stores from CO-OP and 800 funerals throughout the UK are traded as usual.
A spokesman for the National Crime Agency said: “We are consciously aware of the youngest cyber incidents that affect the retail sector and work closely with our law enforcement companies to examine.
“We take into account the incidents individually, but we are aware that they are connected, and therefore this remains checked.”
The National Cyber Security Center said the attacks should be a “wake -up call” for companies.
CEO Dr. Richard Horne said: “The disturbance of the recent incidents that affect the retail sector are of course the reason for the affected companies, their customers and the public.
“The NCSC continues to work closely with organizations that have told us to fully understand the type of these attacks and to give the broader sector competent advice on the basis of the threat.
“These incidents should act as a wake-up call for all organizations. I ask the managers to follow the advice on the NCSC website to ensure that they have appropriate measures to prevent and react effectively.”