Security Experts:

Improved Malware Protection Introduced in Firefox Browser

Starting with Firefox 31, the malware detection mechanism integrated into the Web browser has been expanded to include downloaded files, Mozilla announced on Wednesday.

Firefox has been providing protection against dangerous websites by using the Google Safe Browsing API. However, the latest version, released on Tuesday, is designed to warn users not only when they try to visit malware or phishing sites, but also when they attempt to download harmful files. This is possible because in addition to a list of potentially malicious websites, Google also provides a list of malicious files.

The security feature will be improved even more in the next release of the Web browser, which is scheduled for September, Mozilla said.

 "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," explained Sid Stamm, senior manager of security and privacy engineering at Mozilla.

"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," Stamm added.

Tests conducted by Mozilla have shown that the new feature reduces the amount of undetected malware by half, Stamm said.

According to Monica Chew, lead privacy engineer at Mozilla, the feature can be turned off by disabling malware detection in Safe Browsing from the Preferences -> Security menu. It's worth noting that there is only one setting for both websites and file downloads so users can't disable just one of the protection features.

"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," Chew said in a post published Thursday on her blog.

In addition to offering enhanced protection against malware, Firefox 31 itself is more secure against cyberattacks since Mozilla has fixed a total of 11 vulnerabilities with this release.


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Eduard Kovacs (@EduardKovacs) is a contributing editor at SecurityWeek. He worked as a high school IT teacher for two years before starting a career in journalism as Softpedia’s security news reporter. Eduard holds a bachelor’s degree in industrial informatics and a master’s degree in computer techniques applied in electrical engineering.