Whether indoors or outdoors, surveillance cameras are increasingly colonizing our space. We might not agree, but at least one advantage is that we see them.
Indeed, there is also a whole much more harmful side offer, hidden cameras. They are the size of a dime and only cost a few dozen dollars on eBay or Alibaba. Like surveillance cameras, they can be connected to the Internet and controlled simply by a mobile application.
The problem is, these cameras are made to violate privacy. Their small size allows them to be installed behind a ventilation grill, instead of a light diode on a clock radio, in a flowerpot, etc. The imagination, in this area, has no limit. In 2019, more than 1,600 South Korean hotel guests were filmed without their knowledge in intimate situations. The perpetrators then broadcast these images in real time over the Internet to members of a voyeur network. A paid service, of course.
So how do you know if you are not the delight of a pervert on the other side of the web? Baidu security researchers Shupeng Gao and Ye Zhang have dismantled a series of hidden cameras and have just presented their findings at the BlackHat Asia 2020 conference.
It turns out that these devices all work more or less the same. Once plugged in, they create a Wi-Fi hotspot. Voyeurs can then use their smartphones to connect and configure them.
An intrinsic function allows the detection
This initial connection is based on the application sending a particular data packet, called a “scanning packet”, which will be recognized by the camera. This, in response, will generate a communication channel with the mobile app. However, there are really only four types of “scanning packets”, because there are only four main cloud platforms that manage almost all of the hidden cameras available on the market. In addition, the cameras continue to respond to “scanning packets” even after having been configured and connected to the Internet.
Therefore, it is possible to detect the presence of a hidden camera simply by connecting to the local Wi-Fi network and broadcasting the famous “scanning packets”. If there is an answer, there is a hidden camera somewhere.
To facilitate the operation, the researchers have developed an Android application that allows this detection to be performed directly from a smartphone. It is available on a Baidu site. Unfortunately, it only exists in Chinese, which limits its use in our regions. Hopefully it will one day be available in French or – at the limit – in English.
This is not the only method for detecting hidden cameras. Thus, the researchers noticed that these devices tended to heat up a lot because they are constantly active. By using a thermal imager such as the Flir One, one can identify hot spots in the surrounding space and thus find potential snitch.
Some hidden cameras also have an infrared diode for operation at night. This diode can be detected with a camera equipped with an infrared filter. In contrast, solutions based on the detection of metal or magnetic fields are not worth much, say the researchers. False positives would be too high.