The Co. Offaly company J Grennan & Sons has warned customers that it was the "victim of a cyber attack" in early December last year.

The company said that "despite having robust security systems in place" the cyber attack had caused significant disruption to its operations.

According to J Grennan & Sons, it immediately engaged with cyber security experts who supported the company's internal IT team and the "incident" was successfully contained.

The company told customers that it has "implemented measures to help prevent any recurrence" and a full investigation has now been completed.

Cyber attack

According to the company, it is "reasonably confident" that the data held on its systems "has not been accessed" and it has "no evidence" that any information has been taken or misused.

However in light of the cyber attack last month it has issued advice urging customers to "remain vigilant".

J Grennan & Sons has also encouraged customers to be alert for any unusual activity including:

Emails, calls, messages from any new source claiming to be from the company;
Requests to click links, open attachments, or share banking or login details;
Instructions to change payment details or send funds to a new account.

The Offaly company has said it "fully appreciates the seriousness of the matter" and it has urged customers to contact it with any questions, concerns or if they do notice anything unusual.

Gardaí

According to the Garda National Cyber Crime Bureau, there have been a number of cyber attacks against critical national infrastructures over the past few years.

It has also warned that businesses have "increasingly found themselves" on the end of unwanted cyber attention from criminals and curious hackers.

The bureau has also highlighted that Irish businesses of "all sizes" and private individuals have seen their data encrypted with malware.

The number of ransomware attacks has remained steady but in the area of small and medium businesses, it "continues to grow", the bureau said.