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Devices that use Wi-Fi can be tricked into draining their own batteries, thanks to a quirk in the way that wireless networks operate. Security experts say that although the ability seems innocuous at first glance, it could be exploited to take out security cameras, or form part of a coordinated attack with other vulnerabilities.

at Stanford University in California and his colleagues have discovered a phenomenon that they call 鈥減olite Wi-Fi鈥�, in which devices acknowledge and reply to messages from any other wireless device, no matter whether they have the password or permission to be on the same network. The responses contain no sensitive information themselves, but Abedi鈥檚 team has nonetheless found ways that their transmission can be abused.

In a , the researchers discovered that if fake packets of data were sent continuously, and the direction from which the responses came was monitored over time, it was possible to observe devices moving around inside a building 鈥� indicating that they could be phones or smartwatches. This allowed them to track people鈥檚 movements.

Now, the researchers have found that they can continuously ping battery-operated Wi-Fi devices and prevent them from entering sleep mode, rapidly running down their power. This can be done with a device costing just $10 that sends out fake packets of data.

The team tested 5000 different devices from 186 manufacturers and found they were all vulnerable to this attack: if a fake data packet was sent to them, they responded with an 鈥渁cknowledgement鈥� or 鈥淎CK鈥� signal. It worked at a distance of up to 200 metres.

Abedi says Wi-Fi devices are designed to operate this way, so they can indicate to other machines that the transmission is working. If devices waited to authenticate each other before replying, then wireless networks would virtually grind to a halt, meaning that the flaw would be difficult to fix, he says.

at Ulster University, UK, says that draining batteries seems innocuous at first glance, but that it could enable dangerous attacks when packaged together with other vulnerabilities.

For example, burglars could drain the battery of a Wi-Fi-enabled security camera, he says. 鈥淚f they鈥檙e being pinged regularly, you can completely drain them. And these attacks always get better, and then use cases can expand.鈥�

at cybersecurity firm ESET says that when protocols are created, it is impossible to foresee the way they could be abused. 鈥淲hen devices are developed, even with security in mind, the full scope of creative techniques to exploit a device is simply endless,鈥� he says. 鈥淏eing able to send unauthorised packets of data on a network can be very dangerous.鈥�

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