The group, which includes Scenic Luxury Cruises & Tours, Emerald Cruises and Evergreen Tours, said the breach involved "unauthorised access" to its IT systems.
As per its security protocols, the company has "ring-fenced" its systems to minimise any further impact and launched an investigation into the breach.
A spokesperson for the group said: "We have engaged the services of an external cybersecurity company and their forensic experts, to assist our internal IT team to resolve this situation and bring our systems back online to full capacity.
"Investigations by our IT department and the cybersecurity experts are ongoing, and we continue to work in collaboration with the relevant authorities.
"We appreciate your patience and understanding during this time, as there may be delays in responding to enquiries. We apologise for any inconvenience this may cause and wish to assure you that we are doing everything possible to resolve this issue."
As a risk assessment continues, Scenic’s IT systems will remain offline until the threat has been mitigated.
Scenic said there is currently no evidence to indicate that any guest, staff data or personal information has been impacted.
Rob Voss, chief operating officer for Scenic Group, confirmed the business will continue to operate its cruise and tours programme as scheduled despite the impact the attack has had on its IT systems.
"Scenic Group will work closely with our partners to ensure delivery of our guest experience is not impacted," he added.
