Thank you Henrik and sorry for my late response.
I have taken a look into creating a solution with the .NET-API. I think the best solution for my case is a ViscualCron Job in combination with a C# script. Here's what I'm planning to do.
I created a VisualCron Job where a User can make an input with his credentials (popup-Task). The input get's passed to the C# script which updates the Connection with the new password.
I have two questions about that.
The first one: is there an elegant way to forward user input to another task? My current approach is to have a Popup-Task where the user puts adds his credentials, then the next task reads the output of the popup-taks: {TASK(d168bd52-0f07-458c-89a8-81f4fcb14cd3,StdOut)} The problem here is, that everyone can read the credentials in the Output-log.
The other question: Am I on the right track to update a connection in the following way: get the connection that has the same name as the users inputname -> set the password of this connection to the same password as the users inputpw -> Save the connection
My current approach on this topic looks something like this, but I'm not sure if I've got the right understanding of Connection, Connections and ConnectionClass:
Connections c1 = new Connections(s);
foreach(ConnectionClass cc in s.Connections.GetAll())
{
if(cc.Name == inputName)
{
cc.PassWord = inputPwBytes; //this is the user's new password
c1.Update(cc);
}
}