From The Apple Wiki
Original author(s)a1exdandy, nyan_satan
Developer(s)a1exdandy, nyan_satan, synackuk
Initial release18 Jun 2020 (2020-06-18)
Operating systemWindows, macOS, Linux
WebsiteGitHub (original)
GitHub (updated fork)

checkm8-a5 is a tool based on the checkm8 Exploit that puts A5-based devices in pwned DFU Mode. The tool takes the form of an Arduino sketch, and requires an Arduino Uno with a USB Host Shield attached.


The Arduino Uno used should be an OEM one, indicated by the PCB being green and having things like Arduino logos and "Made in Italy" text on it. A USB Host Shield must be attached to the Arduino so a device can be plugged in. On the opposite side of the shield from the reset button, an LED should be placed into the shield connector, with the negative end (short prong) being in the slot labeled "GND" and the positive end (long prong) being in the second slot from the right of the gap.


  1. Remove the -master suffix from the name of the checkm8-a5-master folder that the sketch is extracted to.
  2. In the Arduino program, load the checkm8-a5.ino sketch.
  3. In the third line of the sketch, make sure that the right CPID is written for the device you're pwning (the default is 8942).
  4. Go to the "Tools > Port" menu and select the port your Arduino is connected to.
  5. Upload the sketch to the Arduino, and when it's done, unplug the Arduino from your computer
  6. Plug your device into the USB port on the USB Host Shield, then plug the Arduino back into your computer.

The LED should blink three times. When your device is pwned, the LED should light up permanently.