A user has recently notified me that he had received a message from another user on the group with the following message:
"Due to recent hack attempts we are monitoring steam accounts VERY closely. We have noticed 2 different IP addresses logged into your account recently. In order to verify that YOU are the correct owner we require you to log in {LINK REMOVIDO}(******************.tk/). Once you log in your IP will verify who you are and will be set to your steam account."

DO NOT give your Steam account information to ANYBODY or enter it on ANY website other than official Steam pages. The dot TK domain extension should have given it away...