Staff at Revenue were warned under no circumstances to use their work password anywhere else after 137 of its employees were caught up in a data breach involving a supplier.
The names, email addresses, job titles, phone numbers, and office addresses of the Revenue workers were reported to be at risk of exposure during a "ransomware" attack on the company Pitney Bowes.
An internal Revenue email claimed "negotiations did not go well" on attempts to contain the breach and that sone records had already been published online.
It said that Pitney Bowes was a supplier of franking machines for the Revenue Commissioners.
In the email to all staff in late April, Revenue's security team said home addresses were unlikely to have been compromised unless people had one of the machines at their home.
"I would assume that they only have Revenue related information and not anything related to your personal life," the message said.
It said affected employees could see an increase in the number of scam emails and phone calls in the future.
Revenue security said no passwords were stolen but said it was a good reminder for everybody to be careful.
"Everyone already knows not to use their Revenue password for external sites, even for trusted suppliers, so even if there were passwords it wouldn’t be something for us to worry about, would it?", the message said.
The email said once the names of the 137 staff affected were confirmed, they would be contacted directly to discuss how they could be at increased risk of scam efforts and "social engineering attacks."
Revenue's IT security said they were using the incident as an opportunity to highlight the risks involved in cybersecurity.
"Do not re-use passwords or at the very least do not use your Revenue password (or anything like it). Limit any data shared to the minimum required," the security team said.
"Always be alert for attackers pretending to be from a trusted source," they added.
Staff were also warned to be vigilant of any unusual requests involving suppliers, using an example of a company submitting an invoice that was three times its normal average.
Asked about the breach, a spokesman for Revenue said Pitney Bowes provided Revenue with various services related to postal and logistics operations.
He said Revenue was alerted to the breach and were briefed by the National Cyber Security Centre (NCSC).
The spokesman said the data exposed could contain the information that was provided when registering for an account.
"It is not known at this stage if each account provided full or partial details at the registration stage," he said.
"All staff on the list have been informed and advised on appropriate precautions against potential phishing activities," he added.
The spokesman said no taxpayer data of any description was involved in the breach and that Revenue continuously monitored for suspect activity.
"There was no requirement to inform the DPC, as this was not a breach of Revenue systems," he stated.
Reporting by Ken Foxe
