I have unfortunately fell victim to this twice.. Once back during Christmas of 2016, my account got h4c|<7d and I couldn't get into it for almost two whole months. I had to make a dummy account, fight with Imvu support for the whole two months just to get a resolution from them and send me a temporary password. Once I finally got it back, most of my stuff was altered before my last log in before the h4c|<.
The second time, it was mainly changing the password before anything real damage happened, like being locked out of my account. Luckily, I've been more well aware of these issues and block any names I don't recognize on there.