Holiday Inn hotels hit by card payment system hack
The owner of the Holiday Inn and Crowne Plaza hotel brands has disclosed that payment card-stealing malware has struck about 1,200 of its franchisees' properties.
UK-based Intercontinental Hotels Group (IHG) said all but one of the locations affected were in the US, with the other being in Puerto Rico.
Guests have been warned they could have had money stolen as a consequence.
One expert said there might be further hotels affected.
Buckinghamshire-based IHG had previously reported in February that a dozen US hotels that it managed itself had been affected by the same attack.
"Individuals should closely monitor their payment card account statements," a spokeswoman told the BBC following the latest discovery.
"If there are unauthorised charges, individuals should immediately notify their bank.
"Payment card network rules generally state that cardholders are not responsible for such charges."
Other affected brands include Hotel Indigo and Candlewood Suites.
Hijacked card data
IHG said an investigation had detected signs the malware had been active at front-desk payment locations at the hotels between 29 September and 29 December 2016.
However, it only has confirmation that the threat was definitely eradicated last month.
The attack hijacked information taken from the payment cards' magnetic strips as it was being routed through the hotels' computer servers, said the hotel group.
This could include the card number, expiration date and verification code.
IHG does not believe other guest information was stolen.
It has published a tool for visitors to check if hotels they stayed at are among those affected.