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Choicejacking bypasses smartphone charging security

Smartphone users have yet another reason to avoid public phone chargers. Although smartphone and tablet manufacturers have introduced measures to protect users from juice jacking (an attack in which malicious chargers compromise connected mobile devices), cybercriminals have found ways to bypass these safeguards.

The recently emerged method is Choicejacking, a new threat where a malicious device disguised as a charging station manipulates various functions of the device to confirm, without the victim’s input or consent, that that the victim wants to connect in data-transfer mode, which means giving the disguised charging station access to what is on their phone, like photos, documents, and contacts.

“Choicejacking is particularly dangerous because it manipulates a device into making decisions users never intended, without them realising it,” says Adrianus Warmenhoven, a cybersecurity advisor at NordVPN. “Whether it is granting access to data and/or downloading malware, these attacks exploit the trust we place in everyday interactions with our smartphones.”

The risk of juicejacking first arose back in 2011 and since then, OS developers implemented a mitigation, when a smartphone is connected to a device supporting Media Transfer Protocol (MTP) or Picture Transfer Protocol (PTP) — that is a hacker’s computer disguised as a charging port — it asks the user whether to allow data transfer or if they just want to charge the device. However, researchers from Graz University of Technology in Austria have discovered a way to bypass it.

Malicious charging stations can exploit smartphones by impersonating USB or Bluetooth input devices to stealthily trigger data transfer or debug modes. These techniques range from keystroke injection and input buffer overflows to protocol abuse, affecting both Android and iOS (in some cases). The attack can be completed in as little as 133 milliseconds, which is faster than a human blink, making it virtually undetectable.

“Choicejacking represents a dangerous evolution in public charging threats. With a single deceptive prompt, attackers can trick people into enabling data transfer, potentially exposing personal files and other sensitive data,” says Warmenhoven. “Public USB ports should never be treated as safe, and awareness is the first line of defence.”

Tips to avoid Choicejacking

1. Keep smartphone software up to date with the latest security patches.

2. Avoid letting your phone dip below 10% regularly to reduce emergency charging needs.

3. Use a portable power bank, the safest and most convenient option.

4. If available, use a wall socket with your own USB adapter and cable. Avoid using USB ports on public charging stations, such as those found in hotels or airports.

5. Enable ‘Charge only’ mode (available on some Android devices), which adds an extra layer of control.

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