This is a quite uncommon scam, but it's pretty easy to fall for it.
Someone might send you that their minecraft launcher broke because they have no launcher profiles, and will ask you to send a file named "launcher_profiles.json".
DO NOT SEND THIS FILE!
It contains an access token which CAN BE USED TO ACCESS YOUR ACCOUNT!
The scammer might seem very innocent with this scam, that's why it's so dangerous.
(The file is located at C:\Users\(youraccount)\AppData\Roaming.minecraft\launcher_profiles.json)