WPA2: Broken with KRACK. What now?

On social media right now, strong rumours are spreading that the WPA2 encryption scheme has been broken in a fundamental way. What this means: the security built into WiFi is likely ineffective, and we should not assume it provides any security.

The current name I’m seeing for this is “KRACK”: Key Reinstallation AttaCK. If this is true, it means third parties will be able to eavesdrop on your network traffic: what should be a private conversation could be listened in to.

This has happened before with WiFi: who remembers WEP passwords? However, what is different this time around: there is no obvious, easy, replacement ready and waiting. This is suddenly a very big deal.

In truth, WPA2 has been suspect for some time now. A number of attacks against WPA2-PSK have been shown to be successful to a limited degree, WPA2-Enterprise has shown itself to be slightly more resilient.

This is a story that is unfolding as I write. I will update the article with better information as it becomes clear, but please be aware that this is currently all based on public knowledge as of 22:00 UTC 2017-10-15. Public disclosure is planned on the 2017-10-16.

So, this is going to be a horrible Monday morning for IT admins across the world. The practical question is: what now?

Keep Calm

Remember, there is a limited amount of physical security already on offer by WiFi: an attack needs to be in proximity. So, you’re not suddenly vulnerable to everyone on the internet. It’s very weak protection, but this is important when reviewing your threat level.

Additionally, it’s likely that you don’t have too many protocols relying on WPA2 security. Every time you access an https site – like this one – your browser is negotiating a separate layer of encryption. Accessing secure websites over WiFi is still totally safe. Hopefully – but there is no guarantee – you don’t have much information going over your network that requires the encryption WPA2 provides.

So, we’re alright?

In a word, No. There are plenty of nasty attacks people will be able to do this. They may be able to disrupt existing communications. They may be able to pretend to be other nodes on the network. This could be really bad – again, they won’t be able to pretend to be a secure site like your bank on the wifi, but they can definitely pretend to be non-secure resources. Almost certainly there are other problems that will come up, especially privacy issues with cheaper internet-enabled devices that have poor security.

You can think of this a little bit like your firewall being defeated. WiFi encryption mainly functions to keep other devices from talking on your network (the security otherwise has been a bit suspect for a while). If that no longer works, it makes the devices on your network a lot more vulnerable – attackers in proximity will now be able to talk to them.

Story for your boss

Keep it simple, and ideally get ahead of the game by communicating now. Re-iterate:

• this won’t let people who are not physically present into your networks;
• it’s unlikely any data is protected by the encryption WPA2 provides; in particular, accessing secure websites is still fine;
• think about increasing the level of security of the nodes on your network if possible – make sure your AV is up-to-date, firewalls turned on, etc.;
• if you’re paranoid about certain data or systems, turn off WiFi and switch to one of an internal VPN, a wired ethernet connection or mobile data (for WAN access);
• that you are on top of the situation and monitoring the best next steps.

In terms of what to do, in many ways, we’re at the behest of our vendors. If you have a high quality vendor (I would include companies like Ruckus and Cisco in this bracket, for example) I expect new firmware to be available very shortly to mitigate these problems. This may well result in incompatibility with existing devices: as a business, you will need to make a decision in that case (unless you need compliance with PCI-DSS or similar, in which case you likely have little choice).

Story for friends / family

This is where it gets really sucky. Lots of us have old routers at home, which have no chance of a firmware upgrade, and lots of WiFi equipment that may well not get a protocol upgrade if one is required. Right now, it sounds like all this stuff is going to be worthless from the perspective of encryption.

Reiterate the same points as above:

• secure websites are still secure, even over WiFi;
• think about setting your computers to “Public Network” mode – that increases the level of security on the device relative to “Private / Home Network” modes. Remember, if third parties can get onto our home networks, they’re no longer any safer than an internet cafe;
• if you’re paranoid about your mobile, turn off WiFi and use mobile data when necessary;
• it sounds like no similar attack against ethernet-over-mains power line is possible, so home networks based on mains plugs are problem still ok;
• keep computers and devices patched and up-to-date.

What for the future?

As I said before, this is a big problem, but not one that was unexpected. A number of encryption protocols have been problematic over the years; many of the implementations of those protocols have been even worse.

It’s clear to me that “Internet of Things” type devices will be the hardest hit. Devices with embedded WiFi for secondary functional purposes, like TVs and baby monitors, are unlikely to get proper updates. As a protocol problem, it’s possible we will be forced to choose between security and functionality, and many users will choose the latter – it’s a difficult problem to weigh.

I would love to say there’s an easy answer. I think it’s important that networks become increasingly software-defined, and that it makes sense that future standards focus on that runtime rather than the protocol itself. We cannot rely on vendors to keep devices up-to-date either (for many reasons), but previous attempts at standardising a runtime (like UEFI) aren’t promising, either technically or security-wise.

As consumers, we have to continually question the security credentials of devices we buy, and demand the best evidence of their security. This is a tough ask; even in the IT world, buying “secure” is difficult. In tech we must strive for better.