Firefox 87 SmartBlock. Credit: Mozilla

With the release of Firefox 87, Mozilla has introduced a safe browsing feature called SmartBlock. SmartBlock allows users to avoid online tracking tools while browsing the Internet. This way, users can surf the Web without worrying if their information is being scrutinized.

Mozilla began its safe browsing mission in 2015 with the built-in Content Blocking feature that automatically blocks images, scripts and related content from third-party entities. This block capability helps to prevent cross-site scripting tracking by companies blacklisted by the data protection company, Disconnect.

However, in providing these tracker blocking features for Private Browsing and Strict Mode, developers have come to realize that such safety mechanisms can also sometimes block necessary web page function. As a result, blocking tools can inhibit images, videos and even entire websites from loading.

To mitigate the potential obstacle of web page interference, the SmartBlock feature automatically restores websites that have been damaged by other blocking features without disrupting user privacy. SmartBlock operates by providing scripts for the web page that support the site exactly how its original scripts would, so that the web page can render normally without risking user security. Of course, these replacement scripts do not contain any code that would track the user.

In fact, the Mozilla team plans to keep improving upon such features that continue to protect users browsing the Web while also maintaining their access to and intended destination web pages. So far, the teams behind the NoScript and uBlock tools have assisted with developing SmartBlock's capabilities.

In addition to blocking blacklisted tracking scripts, SmartBlock also has the ability to trim URLs from embedded images and scripts. This sort of referrer trimming removes everything from cross-origin web requests save for the embedding domain itself. The reason safeguarding your data while browsing the Internet is so important lies in how third-party websites track that data—namely, by ingesting bits of your information whenever you embed an image or script from their web into your own.

This basically means that whenever you implement an artifact from their , the owners of that site receive a URL containing some of your data along with their own. Luckily, SmartBlock ensures third-parties cannot view any bits of information from your end.

More information: Wisniewski, T. "Firefox 87 Introduces SmartBlock for Private Browsing." Mozilla Security Blog, Mozilla, 23 Mar. 2021, … roducing-smartblock/