We are always looking for ways to help protect people better from the constant threat of malicious software. For years Firefox has utilized Google’s Safe Browsing phishing and malware protection to help keep you from accidentally visiting dangerous sites. This protection feature works by checking the sites that you visit against lists that Firefox downloads of reported phishing and malware sites. (For more details, check out this page.)

Firefox is about to get safer.

Until recently, we only had access to lists of reported malicious web sites, now the Safe Browsing service monitors malicious downloaded files too. The latest version of Firefox (as of July 22) will protect you from more malware by comparing files you download against these lists of malicious files, and blocking them from infecting your system.

The next version of Firefox (released in September) will prevent even more malicious downloads on Windows. When you download an application file, Firefox will verify the signature. If it is signed, Firefox then compares the signature with a list of known safe publishers. For files that are not identified by the lists as “safe” (allowed) or as “malware” (blocked), Firefox asks Google’s Safe Browsing service if the software is safe by sending it some of the download’s metadata. Note this online check will only be performed in Firefox on Windows for those downloaded files that don’t have a known good publisher. Most of the common and safe software for Windows is signed and so this final check won’t always need to happen.

In our preliminary testing, we estimate this new malware protection cuts the amount of malware that slips through Firefox’s protections in half. That’s a lot of malware that will be stopped in its tracks.

And of course if you don’t want to send Google data about the few downloads that don’t match these lists, you can turn off malware protection. But we believe eradicating malware is critical for most people, and expect this new feature to help work behind the scenes to keep you safe as you browse.

For more details, head on over to Monica’s blog post.