IEEE group recommends random MAC addresses for Wi-Fi security

According to new recommendations by an IEEE study group, the Wi-Fi protocol needs to be updated to use randomly generated addresses for better security and privacy.

Today, the 802.11 Wi-Fi standards are designed so that each mobile device gets its own, unique media access control (MAC) address -- which allows spies, criminals, and advertisers to track mobile users.

"Because of the uniqueness of the identifier and the fact that they're not encrypted, you can easily make a connection between the identifier and the user," said Juan Carlos Zuniga, principal engineer at InterDigital and chair of the IEEE 802 Privacy Executive Committee Study Group.

That's because the protocols developed over the course of decades were originally designed to work over local networks with stationary devices.

Today, many people carry at least one mobile device with them where ever they go, and the identifiers are sent out in the clear, whenever a device connects to a wireless network, or tries to.

"So you can identify the walking path, where they work, where their live, what their like income is, what their age range is, in a scarily easy way," he said.

Zuniga said he hopes to see his group's recommendations incorporated into the next version of the 802.11 standard, which would be either 802.11ax or later.

That could take years, he said.

But, until then, manufacturers could proactively generate random identifiers for their devices, without waiting for the standard to catch up.

Zuniga said that this approach has been through three trials at recent meetings of the IEEE group.

"Our meetings look like conferences," he said, "With hundreds of people attending several times each year."

This approach works, he said.

"We have tried it on 802.11n, on 802.11gs and 802.11ac," he said. "This is something that can be done by a firmware update, if manufacturers decide to do so."

It does require changes at either the hardware or the operating system layer, however, not an app.

"I don't think today you can do it with over-the-top software," Zuniga said. "It really has to be part of the design."

But the newer the device, the more likely it is the fix can be distributed with an operating system update, he added.

For example, Apple's latest iOS update includes privacy features for when the devices are scanning for wireless networks -- but the update only works while scanning, not for after the device is connected, and it only works on the most recent iPhone models.

"Our study showed that this can be done, and the benefits are huge, and the problems that can be caused are very, very minimal," he said. "You can easily go around them or fix them."

For example, some applications expect each device to have a unique, permanent address instead of a randomly-generated changing one.

For example, Zuniga said, hotels that charge for Wi-Fi may use this address to identify the device as being paid up for the next 24 hours.

"And if your identifier changes, you would have to pay again," he said.

Another possible complication is if an enterprise uses these identifiers for authentication into corporate networks.

Developers who have become accustomed to using MAC addresses in this way should start planning for alternate identification mechanism, which could include secure tokens or standalone apps.

Zuniga pointed to recent news reports about international business travelers targeted by espionage as evidence that this security hole needs to be plugged.

"Whether it's an intelligence agency or a commercial entity doing non-privacy-friendly practices -- or a criminal -- for us, it doesn't make a difference," Zuniga said. "Anywhere you have these Wi-Fi identifiers today, anyone with simple PC tools can open them up and start sniffing the air."

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