The HopStrem extension claims to improve one’s browsing experience with filtered pop-ups and advertisements when you surf. However, it has been found to be a browser hijacker that will attempt to commandeer your browser search and homepage. This browser hijacker will send you to malicious websites to get money from you or infect your computer further. It may also monitor your browsing habits and prevent you from changing your settings back.
HopStrem is usually installed through bundled software without you knowing. Remove it immediately.