When connecting to the Solax Cloud MQTT server the username is the "registration number", which is the 10 character string printed on the SolaX Power Pocket device / the QR code on the device. The password is derived from the "registration number" using a proprietary XOR/transposition algorithm. Attackers with the knowledge of the registration numbers can connect to the MQTT server and impersonate the dongle / inverters.
CWE-330