Laptops with proprietary software from Google, called Chromebooks, are very popular in American educational institutions. Many schools and colleges give out these devices to everyone for educational purposes. Of course, such devices have many software restrictions set by the administrator when registering for the enterprise. For example, third-party applications cannot be installed on such devices, many system settings cannot be changed, etc. In addition, it is not possible to unregister a device by yourself, only an administrator can do this.
The new exploit allows users to unregister enterprise-registered Chromebooks, allowing them to install whatever apps they want, bypass restrictions, and even do a factory reset.
Security researchers from the Mercury Workshop team have developed an exploit under the funny name "Shady Hacking 1nstrument Makes Machine Enrollment Retreat", abbreviated as "Sh1mmer". The tool, as the name suggests, allows non-admin users to unenroll their Chromebooks from Enterprise Management. Especially enterprising comrades can thus untie their Chromebook and use the entire academic year as their personal one, without any restrictions.
For the exploit to work on a particular Chromebook, there must be an RMA shim that has been leaked to the dark web for public access. Sh1mmer changes its parameters and gives extended access. The researchers listed the boards on which the exploit would work correctly. You can find out the board model on a particular device through the “chrome://version” command in the address bar, and the “board-name” field should contain one of the following values:
brask, brya, clapper, coral, dedede, enguarde, glimmer, grunt, hana, hatch, jacuzzi, kukui nami, octopus, orco, pyro, reks, sentry, stout, strongbad, tidus, ultima, volteer, zork.
RMA shims are disk images stored on USB devices. They contain the ChromeOS components needed to reinstall the operating system, as well as the manufacturer's tools used to repair and diagnose the device.
To use this exploit, you need to download an RMA shim for the desired Chromebook board, use a dedicated online builder from the exploit developer to inject Sh1mmer into it, and then run the Chrome Repair Utility.
Using the steps detailed on the Sh1mmer website, you can download the modified RMA shim and launch the exploit menu.
From this menu, you can unregister or re-register the device, enable USB boot, allow root access to the operating system, open a bash shell, and more.
One Reddit user tested the exploit on his Acer ChromeBook and stated that it was fully functional. The device can be unpaired and reset to factory settings. Another user warned that using this exploit is likely to violate the student code of conduct and could lead to serious consequences.
Google representatives have already said that they are aware of the exploit and are working on fixing the vulnerability.