We expect several customer applications to be impacted throughout the day. We will continue to provide regular updates."
Toll could not be immediately reached for comment.
2020 has begun as another bad year for cyber-security.
January 8 saw currency exchange firm Travelex knocked offline after a "ransomware" attack saw hackers steal customer data then demand money for it to be released.
The BBC reported the hackers had demanded US$6million.
Travelex went back online on January 28. Reuters quoted the company saying it had not paid any ransom.
New Zealand businesses or individuals hit by a cyber-attack are advised to contact Crown agency CERT (the Computer Emergency Response Team) as their first step.
CERT acts as a triage unit, pointing people to the right law enforcement agency or technical contacts.