October 25th, 2017


The foundation of secure home wireless networks cracked this week. (I apologize for the pun. Well, No, I don’t!) KRACK is a Key Reinstallation AttaCK on WPA and WPA2 (Wireless Protected Access and Wireless Protected Access II). If you read my book, Personal Cybersecurity, you know that WPA2 is the best choice for protecting your home wireless system from intrusion. It still is, but without some timely updates, WPA2 is vulnerable to hacking.

Don’t panic

No intrusions have been reported yet, although there almost certainly will be some in coming weeks and months. The vulnerability is in the WPA and WPA2 standard. Consequently, everything that follows the standard is vulnerable. The problem is not with particular implementations. Anything that uses WPA or WPA2 correctly is vulnerable. The security of a component that uses WPA or WPA2 incorrectly is anyone’s guess, but there is a good chance it was insecure even before KRACK was discovered.

What must be patched

The Windows operating system (all versions), Linux, and Apple all are affected.  Internet of Things (IoT) gear such as wireless security cameras, smartphone controlled wireless door locks, thermostats, and light switches are also vulnerable. Practically anything wireless must be patched. Fortunately, the necessary patches have already been written for many components that need them.

Your wireless router must be patched. I read a comment in a Comcast forum that the common Xfinity Technicolor TC8305C combined cable modem and wireless router does not need patching, but I haven’t found any acceptable confirmation of that, and therefore I assume it is wishful thinking. I would appreciate a comment here from anyone who knows more.

Microsoft’s automatically delivered October security update fixed the issue for supported versions of Windows, so you are most likely already safe there. Linux distributions have patches written and it is possible your Linux installation is already safe too. I’m not as well tapped in to the Apple world, so I am not sure what the status is there, but I’m sure lights are burning late in Cupertino if they haven’t spiked it already.

The good news is that the patches are backwards compatible— that means patched components can work side by side with unpatched components without interrupting service.

The bad news

The bad news, and very bad news it is, is that a hacker can use the vulnerability to get into your wireless network from any unpatched component. The IoT is scary: Windows is easily patched automatically and is likely to be safe already, but many IoT devices have no automated patch mechanism and the device manufacturer has no means to even inform you that you are vulnerable. White label gear is especially dangerous because you have few ways to contact the manufacturer. In other words, you are on your own in the IoT.

Some reports say that Android phones are the most vulnerable. For them, you are dependent on your cellular carrier for patches to your phone. Some are more prompt than others. If you are worried, to protect yourself, turn off wireless support on your phone and only use the cellular network for network connections. When your carrier gets around to patching your device, turn wireless back on to save on data charges, if that is an issue.

Switch to wire where you can

If you have a means to switch IoT gear to a wired ethernet connection, that will render the device no longer vulnerable. Same applies to any computer or printer that you are unsure of that uses a wireless connection; turn off wireless and jack the device into your wired network if you can. If you can’t connect by wire, turn the device’s wireless service off or turn the device off entirely. You may have to turn wireless back on to download patches when they are available.

Other reasons for optimism

If you live in a low density population area, you may be less vulnerable. In order to exploit the vulnerability, a hacker must have access to your wireless signals in the air. Ordinarily, that is only within 300 feet from your wireless access point (usually your wireless router). Special antennas can extend that limit, but if strangers can’t get closer than 300 feet, you are pretty safe. The exception to that is if a hacker happens to have taken control of a computer within the 300 foot sphere that can connect to your wireless network. Still, many people in low density areas are fairly safe from intrusion.

Final advice

If you know you are in area where wireless hackers are active, turn off all unpatched wireless devices or use a wired connection. Take inventory of your IoT devices and make sure they are all secure. One way to do this is to log on to your wireless router and review the list of attached devices. Some may be turned off and only appear on the inactive list. If there is any chance that the device might connect in the future, put it on your list of devices to be secured. I estimate that you have some weeks to react, but that margin will disappear quickly. You can expect that criminals are working weekends to write cheap exploit kits for sale to script kiddies on the dark web. The kids will then drive around with laptops looking for vulnerable wireless. It has a name: “war driving.” Stay in front of them. If you have to trash some unsafe unpatchable IoT gear, do it now, swallow the loss, and take a lesson.

Even if your network is vulnerable, you are much safer using secure HTTPS connections. If you haven’t installed HTTPS Everywhere from the Electronic Frontier Foundation on your browsers, now would be a good time. Get it here.

For further technical information on KRACK, check out Brian Krebs and this post from the discoverers of the vulnerability.

Late update

A friend pointed me to this article in Ars Technica. The gist is that most Android phones are not yet patched against KRACK as of December 1, 2017, but the Android layers of security are strong enough to render the threat negligible. I will not rest easy until my Android phone is patched, but my fears are likely excessive.

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