No matter how drained your cell phone, tablet or laptop battery might be, the FBI says you should avoid using free USB charging stations when you travel.

The FBI office in Denver issued a blunt warning last week that public USB ports, like those found at airports and shopping malls, pose a threat to your digital security and could be compromised by identity thieves.

“Bad actors have figured out ways to use public USB ports to introduce malware and monitoring software onto devices,” the FBI tweeted. “Carry your own charger and USB cord and use an electrical outlet instead.”

It wasn’t clear what prompted the FBI’s warning. However, concerns about public USB charging ports have persisted for many years.

In 2019, the Los Angeles County District Attorney’s Office issued its own warning about “juice jacking,” as it is often called.

“Once the unsuspecting user plugs in, their phone or electronic device becomes infected,” Deputy District Attorney Luke Sisak said. “Within minutes of being plugged in, the malware could lock the device or send private information like passwords, addresses, or even a full backup of the phone directly to the criminal.”

That free charge could drain your bank account, Sisak warned.

The District Attorney’s Office offered the following tips:

  • Use an AC power outlet, not a USB charging station.
  • Take AC and car chargers for your devices when traveling.
  • Consider buying a portable charger for emergencies.