The LA District Attorney's Office is warning smartphone users not to use public USB charging stations.

Travelers should avoid using public USB power charging stations in airports, hotels and other locations because they may contain dangerous malware, says a fraud alert that was issued by the office.

In the USB Charger Scam, often called “juice jacking,” criminals load malware onto charging stations or cables they leave plugged in at the stations so they may infect the phones and other electronic devices of unsuspecting users. The malware may lock the device or export data and passwords directly to the scammer, said the alert.

Instead, officials recommend that travelers use an AC power outlet, not a USB charging station and consider buying a portable charger for emergencies.