We provide tools to perform low-layer attacks such as reactive and constant jamming using commodity devices. Reactive jamming allows you to block specific Wi-Fi packets. For example, all beacons and probe responses of a specific Access Point (AP) can be jammed. It has been tested with the following devices:
This work was the result of the paper [Advanced Wi-Fi Attacks Using Commodity Hardware](https://lirias.kuleuven.be/bitstream/123456789/473761/1/acsac2014.pdf) presented at ACSAC 2014. *If you use these tools in your research, please reference this paper.* Most code is open source, and contributions are welcome. The code of the constant jammer can be requested but is not available publicly. Don't worry, we won't bite.
You can [download a VMWare image](http://people.cs.kuleuven.be/~mathy.vanhoef/modwifi/Xubuntu-Modwifi.7z) that has the drivers, firmware, and user-land tools preinstalled. Just boot it, plug-in the USB dongle, and start experimenting! **The password of the account modwifi is modwifi**. Once booted, you can execute (the public) attacks below.
## Basic Usage
This section describes the attacks that can be executed. We assumed you already downloaded the VMWare image or manually installed the drivers and firmware (see the section "Installation" to install drivers on your existing machine).
*Before doing any attacks it is recommended to disable WiFi.* In particular I mean disabling WiFi in your network manager. Most graphical network managers have an option somewhere named "Enable Wi-Fi". Make sure it's not selected. If you can't find it, perhaps you can disable in the terminal with `sudo nmcli nm wifi off`. Once you have disabled WiFi your OS won't interfere with our attacks.
*If RF-kill is enabled* we'll have to turn it off. Some distributions set RF-kill on after disabling WiFi. But we still want to actually use our WiFi devices. So execute:
Our current implementation of our reactive jammer allows you to block an Access Point. More precisely, all beacons and probe responses will be jammed. Execute it using:
**The first three commands need to be executed only once** after plugging in your dongle. You can stop the reactive jammer using CTRL+C. It may take a few seconds before it actually stops. By modifying the firmware you can reactive jam any kind of packets you like. For example, you could jam all packets of a specific client. Note that only medium to large packets can be reliably jammed (see our paper).
You can verify that this works by monitoring the channel with a second device. Make sure that this device also reports corrupted frames using:
```bash
sudo iw wlan1 set monitor fcsfail
```
This will instruct the driver to also pass corrupted frames to the userland (when in monitor mode). Be warned though, not all drivers properly support this flag. Some will always show corrupted frames. Others will never show corrupted frames. Our drivers and firmware handle this flag correctly!
Want to disable carrier sense in order to perform an experiment? Then execute this:
```bash
modwifi@ubuntu:~$ sudo su
root@ubuntu:~$ mount -t debugfs none /sys/kernel/debug
root@ubuntu:~$ cd /sys/kernel/debug/ieee80211/phy*/ath9k_htc/registers/
root@ubuntu:~$ echo 1 > force_channel_idle
root@ubuntu:~$ echo 1 > ignore_virt_cs
```
Writing 1 to `force_channel_idle` disables physical carrier sense (channel is busy). Writing 1 to `ignore_virt_cs` disables virtual carrier sense (RTS/CTS). Random backoff parameters can also be changed.
This performs constant jamming on channel 6. Because channels overlap, nearby channels will also be jammed. Remember that the constant jamming implementation is not public, but can be requested privately.
The specific scripts we used to easily configure a device to act unfairly are not public. The reason behind this is that it's hard to defend against these kind of attacks. However, some parameters can still be accessed as `debugfs` entries in `/sys/kernel/debug/ieee80211/phy*/ath9k_htc/registers/`.
This is an advanced attack and not for the fainthearted. It clones an existing Access Point on a different channel. This allows us to reliably manipulate encrypted traffic. We used this to break TKIP. See [our paper]() for details. An example on how we used it to verify that our awesome-sauce attacks work:
If an attack or device is not working, you can try the following steps to get it working again:
1. Change the channel of the device. This will reset the wireless chip in the dongle, and perhaps fix the issue.
2. Bring the device up and down using `ifconfig` or `ip link`. This should reset even more settings than just changing the channel.
3. Unplug the device and plug it back it. This reloads the complete firmware.
4. If all else fails, reboot the device.
If you can reproduce a bug, you free to file a bug report.
Another few remarks when using our tools, and doing wireless hacking in general:
- You can only change the channel of a monitor device when no other (virtual) interface is active. So if you have a `monX` interface, you need to bring down (`ifconfig wlanX down`) all other interface (which use that device) first.
- In general you want to kill other processes that are trying to use/configure your WiFi device. Tools like [`airmon-zc`](http://svn.aircrack-ng.org/tags/1.2-beta3/manpages/airmon-zc.8) can help detect which processes might be interfering. Note that `airmon-zc` is the successor of the older `airmon-ng` tool.
You can also install the latest drivers and firmware on your own machine. The quickest method is to grab [one of our release packages](https://github.com/vanhoefm/modwifi/raw/master/releases/modwifi-20150118.tar.gz). Only your wireless stack and drivers will be replaced, all other drivers will remain the same (if you use other wifi devices as well, compile them too). Normal usage of WiFi still works perfectly when these drivers are installed (I use these drivers myself :).
**Reboot** so our new drivers will be used. After that you should be good to go. That is, plug in your dongle, and execute the compiled tools.
If you want to compile the firmware as well, clone the [ath9k-htc repository](https://github.com/vanhoefm/modwifi-ath9k-htc), and follow the instructions there. If you want to modify the driver, you can use the downloaded code in `drivers.tar.xz`. I recommend putting that code in our own repository to keep track of changes. But even better would be to apply patches to the latest Linux kernel, and then either compiling the kernel or using [backports](https://backports.wiki.kernel.org/index.php/Main_Page) to create a release similar to mine. Still, the truly best option would be to contribute patches to this project (git pull request or just mail your patches)!
Our drivers and firmware can be run on a Raspberry Pi. We tested this using raspbian. In order to get it working first download and update some dependencies:
As you can see, we tested this on the 3.12-1-rpi kernel. You can use another kernel if you want, just be sure to download the kernel headers. To enable the 3.12-1-rpi kernel we just downloaded edit `/boot/config.txt` and append:
kernel=vmlinuz-3.12-1-rpi
initramfs initrd.img-3.12-1-rpi followkernel
And to assure our raspberry pi will recognize the device when we plug it in, execute:
Everything is now ready to install our drivers and firmware. Just **follow the instructions under section "Installation"**. Compilation of the drivers can take a while. Finally we have to prevent raspbian from automatically trying to enable and manage WiFi (this interferes with our attacks). First edit `/etc/network/interfaces` and comment out the following two lines:
Now edit `/etc/default/ifplugd` and change the `INTERFACES` and `HOTPLUG_INTERFACES` to:
INTERFACES="eth0"
HOTPLUG_INTERFACES="eth0"
ARGS="-q -f -u0 -d10 -w -I"
SUSPEND_ACTION="stop"
This will prevent raspbian from automatically enabling and managing the wireless interface (so we can first put the device in monitor mode and only then enable it). You can now compile the tools and execute the attacks!
To compile the Linux and ath9k-htc firmware, read the documentation of these projects. To backport the modified drivers using the backports project, also see the official documentation of that project. Finally, our tools can be compiled using a simple `make all`. Apart from the `tools` repositories, all work and modifications are performed on the `research` branch. When a new Linux kernel (or firmware) is released, we can easily merge with it. As a result **our code is relatively easy to keep up-to-date**.
For those who also want to start hacking away at the driver and firmware, I recommend first reviewing our patches. This allows you to study what our changes do, and inspect the firmware code at small chunks one at a time. That way it's easier to learn step by step. Maybe you will even find bugs or can make improvements (let us know). Also, in the `ath9k-htc` repository, there is a directory called `docs`. While still terse to read, these documents should be an excellent guide while reading and understanding the code.
