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Implement your own USB device in Python, supported by a hardware peripheral such as Cynthion or GreatFET


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Facedancer 3.0

This repository houses the next generation of Facedancer software. Descended from the original GoodFET-based Facedancer, this repository provides a python module that provides expanded Facedancer support -- including support for multiple boards and some pretty significant new features.


Install this package with the following command:

pip install facedancer

After that you can import the facedancer package as usual:

$ python
>>> import facedancer

Where are my scripts?

Facedancer 3.0 is a ground-up rewrite of the original emulation core and does not support legacy scripts.

If you're using scripts or training materials that depend on features or APIs deprecated in v3.0.x you can install the latest v2.9.x release of Facedancer with:

pip install "facedancer<=3"

Legacy applets and examples can be found in the v2.9.x branch.

What is a Facedancer?

Facedancer boards are simple hardware devices that act as "remote-controlled" USB controllers. With the proper software, you can use these boards to quickly and easily emulate USB devices -- and to fuzz USB host controllers!

This particular software repository currently allows you to easily create emulations of USB devices in Python. Control is fine-grained enough that you can cause all kinds of USB misbehaviors. :)

For more information, see:

USBProxy 'Nouveau' and Protocol Analysis

A major new feature of the newer Facedancer codebase is the ability to MITM (Meddler-In-The-Middle) USB connections -- replacing one of the authors' original USBProxy project. This opens up a whole new realm of applications -- including protocol analysis and live manipulation of USB packets -- and is especially useful when you don't control the software running on the target device (e.g. on embedded systems or games consoles).

+------------+   |  +--------------------------------+   +---------------------------+   |  +--------------+
|            |   |  |                                |   |                           |   |  |              |
|  PROXIED   |   |  |         HOST COMPUTER          |   |    FACEDANCER DEVICE      |   |  |  TARGET USB  |
|   DEVICE   <------>  running Facedancer software   <--->  acts as USB-Controlled   <------>     HOST     |
|            |   |  |                                |   |      USB Controller       |   |  |              |
|            |   |  |                                |   |                           |   |  |              |
+------------+   |  +--------------------------------+   +---------------------------+   |  +--------------+
                 |                                                                       |
                 |                    MITM Setup (HOST + FACEDANCER)                     |

This feature is complete, but could use more documentation. Pull requests are welcome. :)

How do I use this repository?

First, you'll likely want to set the BACKEND environment variable, which lets the software know which type of Facedancer board you'd like to use. If this variable isn't set, the software will try to guess for you based on what's connected. It doesn't always make the best guesses, so you're probably better off setting it yourself.

Next, you'll probably want to check out one of the examples, or one of the pre-made scripts. Examples in the new syntax are located under examples. The core Facedancer scripts in the "old" syntax are located in legacy-applets.

For example:

export BACKEND=greatfet

What boards are currently supported?

  • The Cynthion USB Test Instrument (BACKEND=cynthion)
  • The GreatFET One (BACKEND=greatfet)
  • The NXP LPC4330 Xplorer board. (BACKEND=greatfet)
  • The CCCamp 2015 rad1o badge with GreatFET l0adable (BACKEND=greatfet)
  • All GoodFET-based Facedancers, including the common Facedancer21 (BACKEND=goodfet)
  • RPi + Max3241 Raspdancer boards (BACKEND=raspdancer)

Note that hardware restrictions prevent the MAX3420/MAX3421 boards from emulating more complex devices -- there's limitation on the number/type of endpoints that can be set up. The LPC4330 boards -- such as the GreatFET -- have fewer limitations.

For a similar reason, the MAX3420/MAX3421 boards (BACKEND=goodfet or BACKEND=raspdancer) currently cannot be used as USBProxy-nv MITM devices. All modern boards (BACKEND=greatfet) should be fully functional.

What boards could be supported soon?

  • Any Linux computer with gadgetfs support (e.g. the Pi Zero or Beaglebone Black)
  • Anything supporting USB-over-IP.

What features do you plan on adding?

The roadmap is under development, but in addition to multi-board support, this repository will eventually be home to some cool new features, including:

  • High-speed ("USB 2.0") device emulation on devices with USB 2.0 PHYs.
  • On-the-fly generation of USB device controllers in gateware.

Whose fault is this?

There are a lot of people to blame for the awesomeness that is this repo, including:

  • Kate Temkin (@ktemkin)
  • Travis Goodspeed (@travisgoodspeed)
  • Sergey Bratus (@sergeybratus)
  • Dominic Spill (@dominicgs)
  • Michael Ossmann (@michaelossmann)
  • Mikaela Szekely (@Qyriad)
  • anyone whose name appears in the git history :)


... are always welcome. Shoot us a PR!