A security researcher has uncovered claims that hackers have compromised multiple registers in restaurants, coffee shops and gift shops in various Hilton hotel properties in the U.S., in a wide-reaching credit card breach.

According to security journalist Brian Krebs, multiple banks have pointed to a pattern of credit card fraud in a “large number of Hilton Hotel and franchise properties across the United States”, reports Krebs in his blog.

The complete account of the findings can be found here.

While the number of accounts compromised are still unclear, the malware was reportedly active from 21 April to 27 July this year. Visa communicated confidential alerts to multiple banking and financial institutions about the breach. The alerts issued by Visa toward the banks included the compromised credit cards, but the breached locations were kept confidential.

However, sources at five different banks have now told Krebs that the one common detail among the breached cards was their usage at Hilton properties.

Now the target of a credit card breach, the compromised Hilton properties include:

The Embassy Suites

Doubletree

Hampton Inn and Suites

Waldorf Astoria Hotels & Resorts, among others.

Related article: Phishing Scam Affects Travelers Using Hotels.com

Krebs believes the malware employed by the hackers is likely to have infected point-of-sale (POS) terminals to steal credit card information. Several credit cards have already been used to make fraudulent transactions.

In a statement addressing claims of the security breach, a Hilton spokesman said:

“Hilton Worldwide is strongly committed to protecting our customers’ credit card information.

“We have many systems in place and work with some of the top experts in the field to address data security. Unfortunately, the possibility of fraudulent credit card activity is all too common for every company in today’s marketplace. We take any potential issue very seriously, and we are looking into this matter.”

Krebs also reports of the possibility of the credit card breach dating back to November 2014. At present, it is still unclear as to how many Hilton properties are affected by the breach.

Hilton is just only the latest hotel chain to have been struck by recent credit card breaches. Several major U.S. hotels and corporations that deal with numerous credit card transactions are frequent targets of malware-wielding hackers who steal credit card details in droves.