Beijing forensic institute cracks AirDrop transmission, helping police trace senders of ‘inappropriate messages’
Published: Jan 09, 2024 06:00 PM


According to Beijing Municipal Bureau of Justice (BMBJ), a local forensic institute has cracked the transmission principle of AirDrop function of Apple devices, which enables mobile phone number and email address of the AirDrop content sender to be extracted from content receivers, while authorities have received more complaints from public over receiving offensive and inappropriate messages from other anonymous Apple devices.

This technical breakthrough has successfully helped the public security authorities identify a number of criminal suspects, who use the AirDrop function to spread illegal content, BMBJ said through a releases posted on its website on Monday. 

According to the BMBJ, the Beijing police have received reports from the public that their iPhones received videos with "anonymous inappropriate messages" in subway in Beijing. Following investigation, the police found that the suspects took advantage of the AirDrop function to anonymously spread these inappropriate messages including pictures, videos, audio and other files, in crowded public spaces like transport hubs, bus stops or shopping malls. 

As AirDrop function allows anonymous transmission without an internet connection, it is almost impossible to effectively regulate this behavior through conventional network monitoring means, which has become a challenge for public security organs to crack these cases, and some internet users have started to imitate this behavior. Therefore, it is necessary to quickly identify the source of the sender and determine their identity in order to avoid negative consequences, according to the release. 

A local forensic institute named "Wangshen Dongjian" was commissioned to analyze iPhone device logs. A rainbow table correlating phone numbers and email accounts was created during investigation, and has "effectively assisted the police in identifying several suspects" involved in such cases.

The breakthrough of AirDrop's anonymous traceability technology has improved the efficiency and accuracy of case detection, and prevented the further spread of inappropriate information and its potential adverse effects, the BMBJ said. 

Apple has limited the use of the AirDrop wireless file sharing function on devices in Chinese mainland in November 2022, after some anti-China forces used the function to spread inappropriate digital leaflets, according to media reports. After the updates, users can only opt in to receive files from non-contacts during a 10-minute window before it automatically shuts off.

Concerns over the AirDrop feature are global. Western nations like US, UK, and Australia also noticed the rising of "cyber flashing," where explicit and abusive images are anonymously sent to strangers through iPhones.

On May 10, 2023, the Metro branch of the Hangzhou Public Security Bureau issued a notice saying that a female passenger received an explicit picture through AirDrop on Hangzhou subway from a stranger," triggered huge amount of public attention.