The firmware upgrade function in the admin web interface of the Rittal IoT Interface & CMC III Processing Unit devices checks if
the patch files are signed before executing the containing run.sh
script. The signing process is kind of an HMAC with a long string as key
which is hard-coded in the firmware and is freely available for
download. This allows crafting malicious "signed" .patch files in order
to compromise the device and execute arbitrary code.