Wednesday, July 23, 2014

Download files more safely with Firefox 31

Did you know that the estimated cost of malware is hundreds of billions of dollars per year? Even without data loss or identity theft, the time and annoyance spent dealing with infected machines is a significant cost.

Firefox 31 offers improved malware detection. Firefox has integrated Google’s Safe Browsing API for detecting phishing and malware sites since Firefox 2. In 2012 Google expanded their malware detection to include downloaded files and made it available to other browsers. I am happy to report that improved malware detection has landed in Firefox 31, and will have expanded coverage in Firefox 32.

In preliminary testing, this feature cuts the amount of undetected malware by half. That’s a significant user benefit.

What happens when you download malware? Firefox checks URLs associated with the download against a local Safe Browsing blocklist. If the binary is signed, Firefox checks the verified signature against a local allowlist of known good publishers. If no match is found, Firefox 32 and later queries the Safe Browsing service with download metadata (NB: this happens only on Windows, because signature verification APIs to suppress remote lookups are only available on Windows). In case malware is detected, the Download Manager will block access to the downloaded file and remove it from disk, displaying an error in the Downloads Panel.

How can I turn this feature off? This feature respects the existing Safe Browsing preference for malware detection, so if you’ve already turned that off, there’s nothing further to do. Below is a screenshot of the new, beautiful in-content preferences (Preferences > Security) with all Safe Browsing integration turned off. I strongly recommend against turning off malware detection, but if you decide to do so, keep in mind that phishing detection also relies on Safe Browsing.

Many thanks to Gian-Carlo Pascutto and Paolo Amadini for reviews, and the Google Safe Browsing team for helping keep Firefox users safe and secure!