The latest in a string of hacks against retail point-of-sale systems has hit the operator of a cloud-based service with about 38,000 business clients.Montreal-based Lightspeed reported the breach on Thursday and said it affected a system that retailers can use from tablets, smartphones and other devices. \u00a0The incident occurs as a growing number of retailers and hotels have been targeted by hackers, who typically install malware into the point-of-sale systems to steal credit card numbers.The breach at Lightspeed targeted a central database that stores client information, the company said. The incident exposed data related to sales, products, and encrypted passwords that clients use to get on Lightspeed's system.In some cases, consumers\u2019 electronic signatures that have gone through the point-of-sale software were also accessed. However, Lightspeed has found no signs that any data was stolen or used.\u201cIt\u2019s worth noting that Lightspeed does not store credit card information, and therefore no cardholder data was compromised in this incident,\u201d said Bradley Grill, a company spokesman, in an email.Although Lightspeed didn\u2019t provide specifics, it said the passwords that were accessed were secured with \u201cadvanced encryption technology\u201d that Lightspeed upgraded in January 2015.An investigation is already under way, and Lightspeed has sent out an email alert to clients. The company is recommending clients change their passwords.Point-of-sale systems have become an attractive target for cyber criminals, often because attacking one system can also mean access to dozens or hundreds of retail stores.In Lightspeed\u2019s case, the company has business clients with $12 billion in transactions annually. These clients include many smaller retailers that sell clothing, jewelry, books and sporting equipment. The company\u2019s retail point-of-sale system operates as a cloud-based service that can work on iPads and other devices.In response to the breach, Lightspeed is limiting \u201cpersonal access\u201d to the company\u2019s production infrastructure and sensitive data. It\u2019s also upgrading its security to detect more advanced attacks.