iSkipper

Report

For full details, see the report.

Warning

If you use this for nefarious purposes, it's your fault if your iSkipper gets you in trouble.

Background

Everybody hates going to lecture just because of stupid iClicker quizzes/questions. Two Cornell University engineers set out to do away with iClicker polling by reverse engineering it and finding any vulnerabilities to exploit. For $5 of parts, an iSkipper can be built that can do any number of evil things:

• Submit hundreds of answers per second under fake iClicker IDs
• Capture everyones else's iClicker ID and associated answer
• After capture of other students ID's, resubmit other peoples answers under something else
• DDOS the base station, so other people can't submit
• Automatically answer questions for you so you can skip lecture

Making Your Own iSkipper

The Software

The software is Arduino based, with several evil examples, and an easy to use API for creating your own evil programs. All we ask is you write your own program/exploit , submit a pull request and put it in the example folder, so other students can enjoy it too.

Installing

Just drag and drop the emulator/iSkipper folder into your Arduino library folder as you would install any other Arduino library. Open the IDE and you should be able to lead examples. One dependency is a Queuing library: RingBufCPP.

The Hardware

• Any Arduino with a 3.3V logic level, a SPI bus, and can source bursts of ~100mA at 3.3V
• The 900 MHz RFM69W/RFM69HW transceiver (can be had on eBay for a few $)

Or get both in one package for $25 from Adafruit. Or support Felix from LowPowerLab and buy a $13 Moteino

License

MIT, but please submit a pull request with your own programs

Current Project Progress

The entire iClicker protocol is proprietary, so it had to be reverse engineered. There is still reverse engineering needing to be done, especially for numerical and alphabetical questions. After decoding ACK, this is what the latest iSkipper can and can not do. Note, there might not be Arduino examples written yet for some of these, but the API supports it. They should be trivial to make.

Basically all that needs to be done is decoding answer packets and ACK packets of numerical&alphabetical questions, then the iSkipper can emulate every part of the real iClicker 2.

How we knew this was possible when we started

Given that your iClicker id can be decoded by the base station, any sort of hashing done before the remote transmits your ID must be reversible, and hence vulnerable.

Techniques/tools Used to Reverse Engineer

• OSINT (datasheets, papers, etc..)
• Logic analyzers
• HEX dumps and disassembly
• Dynamic analysis
• Software Defined Radio captures
• Lots of playing around looking for patterns

Contributors & Universities

Cornell University

• @wizard97

• @orangeturtle739

  They are the founders of this cool project. They made everything become possible.

Purdue University

• @ammaraskar

  The main contributor of decoding ACK and welcome message.

University of Massachusetts, Amherst

• @charlescao460

  Contributor of decoding ACK and testing, also the creator of iSkipper-Software.

• @Th3OnlyN00b, @porocyonak, @aaronterentiev

  Supporters of iClicker base, which allow us to verify our findings.

• @yicao928

  Contributor who made iSkipper avaliable on Android.

Projects Based On iSkipper

• iSkipper-Software
• iSkipper-In-One-Package
• Time-Turner