Sen. Charles Schumer of New York has called on federal law enforcement officials to stop "copy cat websites."
Researchers at Trend Micro found that attackers were targeting Simple Mail Transfer Protocol (SMTP) servers to execute malicious code and an IRC bot.
Although the hack didn't breach the mobile payment app itself, consumer confidence may be shaken.
McAfee found that 60 percent of 504 surveyed IT professionals prioritize security as the primary driver of network design.
The guidance, developed by a PCI Special Interest Group, will help merchants educate staff on protecting cardholder data.