An insecure direct object reference in the Growatt API to retrieve data on solar panels makes it possible to retrieve information on other users.
Solar plant data
At our scouting clubhouse we have solar panels on the roof. These are connected with a Wi-Fi dongle to the internet so that you can view the amount of generated power through the Growatt web site. In order to integrate this data into another application I created an Python API client that retrieves the data on the solar panels.
While looking for an API endpoint that provides higher resolution data, I mailed someone a link that worked for me:
He reported back that he could see the data from my plant, which at least seemed remarkable. It turns out that you can see data from any plant my modifying the
plantId parameter. This is a classic insecure direct object reference. The
plantId contains the number to retrieve. While you have to be logged in, there is no further authorization check whether you are the owner of this plant.
The impact is limited: in this instance, only the name of the plant and the amount of generated power are returned.
This vulnerability was found by accident when sharing a link. My modifying an identifier, another user’s data can be retrieved.