Yes, it sends only your IP to Google. I don't know if it's good or bad for your privacy. There are two times when Firefox will communicate with Google while using Phishing and Malware Protection for sites. The first is during the regular updates to the lists of reporting phishing and malware sites. No information about you or the sites you visit is communicated during list updates. The second is in the event that you encounter a reported phishing or malware site. Before blocking the site, Firefox will request a double-check to ensure that the reported site has not been removed from the list since your last update. This request does not include the complete address of the visited site, it only contains partial information derived from the address. In addition to the regular list updates mentioned above, when using Malware Protection to protect downloaded files, Firefox may communicate with Google to verify the safety of certain executable files. In these cases, Firefox will submit a cryptographic hash of the contents to the Google Safe Browsing service, which helps Firefox determine whether or not the file should be blocked. The [https://www.mozilla.org/privacy-policy.html Mozilla Privacy Policy] describes what data Firefox and Mozilla each receive and how it's handled. The [https://policies.google.com/privacy Google Privacy Policy] explains how Google handles collected data.