I understand you would like Firefox to use only HTTPS connections (and not HTTP connections) as well as prevent the execution of malicious code. Both can be done with the help of add-ons. In particular, the HTTPS Everywhere Add-on will ensure secure connections. As for stopping malicious activity, NoScript Security Script may be what you are looking for. Follow this guide to finding and installing add-ons on Firefox Android: [[https://support.mozilla.org/en-US/kb/find-and-install-add-ons-firefox-android|https://support.mozilla.org/en-US/kb/find-and-install-add-ons-firefox-android]]