Federal Bureau of Investigation officials in Denver are warning travelers and shoppers to avoid public free phone charging portals, warning that "bad actors" use these to install malware and tracking software onto computers and phones.
"Bad actors have figured out ways to use public USB ports to introduce malware and monitoring software onto devices," FBI officials announced in a tweet.
"Carry your own charger and USB cord and use an electrical outlet instead," the FBI officials said.
The free public charging stations have multiplied in recent years as operators of airports, including Denver International Airport, increase services to accommodate growing numbers of people in transit.
Hotel operators and shopping center managers also have installed the charging portals, and FBI officials warned these too could lead to the installation of unwanted surveillance software and malware onto computers and smartphones.