The FBI says you may want to think twice before plugging into a free phone-charging station

• The FBI warned people to avoid using free phone-charging stations found in hotels, airports, and other public places.
• Hackers can insert malware or monitoring software into phones through charging ports, the agency said.

The FBI is warning people to steer clear of free cell phone-charging stations.

According to the agency, hackers have figured out how to gain access to cell phones plugged into the charging ports and can introduce malware or monitoring software onto cell phones and other devices.

Free phone-charging stations are often found in shopping centers, airports, and hotels. Some cities also offer free charging at public bus stops.

However, the FBI's Denver office tweeted that it's best to "carry your own charger and USB cord and use an electrical outlet" rather than relying on the free chargers.

The FBI's Denver office confirmed to Insider that its tweet was a public service announcement for consumers. The agency did not confirm whether it has seen an uptick in these cases.

The FBI is not the only agency to raise alarm bells about this scheme: in 2021, the Federal Communications Commission issued a warning about "juice jacking."

"Malware installed through a dirty USB port can lock a device or export personal data and passwords directly to the perpetrator. Criminals can use that information to access online accounts or sell it to other bad actors," an FCC release from the time said.

Charging stations that have USB cords already plugged in could signal a hack, according to a report in the New York Times.

"A free charge could end up draining your bank account," Luke Sisak, a Los Angeles deputy district attorney, said in a warning first reported by the Times.

Bad actors are constantly innovating to find new ways to trick unsuspecting consumers into handing over money: last summer, Insider's Avery Hartmans was a victim of a complicated "sim-swapping" scheme that resulted in scammers charging $10,000 to her Chase credit card. Read her investigation into the plot here.