Some, if not most, WiFi networks run on 5 GHz nowadays. The problem: most tools are not capable of testing these networks against common vulnerabilities.

2.4GHz vs 5GHz WiFi

Traditionally WiFi runs on a 2.4 GHz frequency range, but that's not the only frequency it can work on. You can see a brief overview of WiFi generations in the image below.

Wi-Fi Generations - Source: https://en.wikipedia.org/wiki/Wi-Fi#Operational_principles

But why do we use different frequencies in the first place?

A lower frequency generally allows for a wider range. Meanwhile, a higher frequency gets you more bandwidth.
It became common to see WiFi routers with both 2.4 and 5 GHz, because this dual-band configuration allows you to use a high-frequency bandwidth in close proximity to the router, while also keeping devices from further away connected through 2.4 GHz too.

There are also WiFi standards for 900 MHz, 3.6 GHz, 4.9 GHz, or even 60 GHz - though they are very popular at the moment.
After all, you need both the router and the client to support the same frequency. And right now, most phones, tablets, and laptops only support 2.4 and 5 GHz WiFi.

The Hardware Problem

Testing your dual-band network against a simple vulnerability like deauthentication can be really hard because most WiFi hacking tools only work with 2.4 GHz WiFi networks.

We at Spacehuhn Technologies would love to provide you with an easy-to-use 5 GHz WiFi research tool, but unfortunately, we haven't yet been able to find a microcontroller that would allow for 5 GHz WiFi hacking.
But we do highly anticipate the upcoming 5 GHz chip(s) from Espressif.

What you need:

  • A computer running Linux (you can use your computer or a Raspberry Pi)
  • A Dual-Band WiFi adapter that supports packet injection (to send custom packets) and monitor mode (to sniff raw network traffic)

We need a Linux machine because the drivers and tools that will use just aren't available for other operating systems. But running Linux is the easy part, finding a supported WiFi adapter however is tricky.

Some built-in network cards will work for WiFi hacking, but you never know for certain until you try them out.
We can recommend getting a rtl8812au based card, like the AWUS036ACM or AWUS036ACH from ALFA. Alternatively, you can also use a Raspberry Pi with nexmon.

Affiliate links:

Installing rtl8812au Driver

To use one of the ALFA cards mentioned above, or other rtl8812au based cards, you need to install the driver. Open a terminal and run:

sudo apt install dkms
git clone https://github.com/aircrack-ng/rtl8812au.git
cd rtl8812au
sudo make dkms_install

Installing mdk4 and aircrack-ng

MDK4 is a "proof-of-concept tool to exploit common IEEE 802.11 protocol weaknesses". It supports 5 GHz, supports a variety of attacks, and is easy to use.
To install it run:

sudo apt install mdk4

But we will also need Aircrack-ng, which is "a complete suite of tools to assess WiFi network security". To install it run:

sudo apt install aircrack-ng

Enable monitor mode

To be able to see all WiFi packets in the air around you, and not just those addressed to your device, you have to put the WiFi card into monitor mode.

First, check the name of the available WiFi interfaces by running:

sudo airmon-ng

As a result, you should see something like this:

airmon-ng output
  • wlan0 is our built-in WiFi
  • wlan1 is the external ALFA WiFi card

Since we want to use the ALFA card, running the following commands will enable monitor mode on wlan1:

sudo ifconfig wlan1 down
sudo iwconfig wlan1 mode monitor
sudo ifconfig wlan1 up

Finding a target network

Now with monitor mode enabled, we should scan for the available WiFi networks and make out which one is ours. Do never run these attacks on other people's networks without permission!

Airodump-ng is an excellent WiFi scanner that is part of the Aircrack-ng suite. Because we're looking to test a 5 GHz network specifically, we additionally need to supply the "band" argument:

sudo airodump-ng wlan1 --band a
airodump-ng output

Once the network you're looking for was found, press CTRL+C to stop airodump-ng. Here our test network is called "spacehuhn5ghz" and it's a WPA2 protected network operating on channel 44.

Deauthing using mdk4

To start deauthing your test network (here "spacehuhn5ghz") run:

sudo mdk4 wlan1 d -E spacehuhn5ghz
mdk4 deauth attack output

Now try to connect to the test network. If you struggle to establish a connection, the attack is working.

That's all! 🙂