The security threat, caused by outdated hardware and obsolete software, has banks rushing to deploy emergency fixes to ATM machines or face new-found risks from malicious software and viruses. If infected, ATM machines could freeze or shut down unexpectedly.
Spokesmen for Ulster Bank, Bank Of Ireland and AIB said that they were working to address the situation but were confident customers would not face any disruption.
The ATM threat comes from a shutdown in software from Microsoft on April 8.
More than 80pc of Irish ATM machines run Windows XP, for which Microsoft is set to cease issuing software updates – meaning breakdowns or vulnerabilities to hacking will no longer be fixed.
The Microsoft move will mean no more security patches issued for the XP computers and systems, which is causing banks and other organisations to scramble for temporary fixes.
There are more than 3,300 ATMs in Ireland. Bank Of Ireland has 1,400 of these, Ulster Bank has 1,100. AIB has 756.
The XP shutdown will affect at least a quarter of all computers worldwide and at least one in 10 Irish PCs, according to the Irish web analytics firm Statcounter. A large chunk of Irish public sector PCs also still use the operating system.
A spokesman for NCR, one of the two biggest ATM manufacturers, said that it believed ATMs would continue to work "normally" after April 8.
"Financial institutions that do not migrate to Windows 7 immediately will have plans in place to maintain the integrity and security of their systems," said the NCR spokesman.
"NCR has plans to support both financial institutions who do not immediately migrate their ATM networks, as well as those interested in upgrading their user experience through Windows 7."
IT security experts say computers using Windows XP are "inherently" more insecure than modern computer systems.
"Windows XP is still an inherently insecure platform compared to others, even with the patches," said Brian Honan, founder of BH Consulting, an IT security firm.
"Computer viruses and malware is much easier to get a grip on machines using it."
Microsoft executives in Ireland say that the software giant has warned business for several years that it would cease security support for machines and devices using Windows XP.