Clearly it was a poor decision to have that command be useable by anyone. It should be exclusive to the server's mods so that images can be vetted.
If that is not possible or not within your skill set to do then it may be wise to just switch the plugin off altogether until a safe solution can be found.
The im command is a plugin specifically added so that we can have whatever images we want.
But you're right, I'm mostly an amateur at server management.
Clearly it was a poor decision to have that command be useable by anyone. It should be exclusive to the server's mods so that images can be vetted.
If that is not possible or not within your skill set to do then it may be wise to just switch the plugin off altogether until a safe solution can be found.
I have made it so you need to be vetted before you can use it.