ETS says "beginning in the 2017–18 testing year (July 1–June 30), your raw score will be determined by the number of questions you answer correctly. Questions you answer incorrectly or for which you mark no answer or more than one answer are counted as incorrect. Nothing is subtracted from a score if you answer a question incorrectly."
< https://www.ets.org/gre/subject/scores/how/ >