During the COVID-19 pandemic, people have become accustomed to using their smartphone cameras to scan small black-and-white square bar codes, allowing them instantly to do everything from access restaurant menus to pay bills. Scanning a Quick Response, or QR code, is convenient and easy. And it is contactless, which can make people feel safer in public places such as restaurants, many of which substituted the codes for paper menus. But cybersecurity experts say QR codes also created new opportunities for fraudsters, who can tamper with them and direct victims to malicious websites to steal the…