Mozilla a few months ago introduced a security architecture for isolating websites. Essentially, this new architecture separates processes into different sites and gives security metrics.
Mozilla has been working on this project for several years but was eventually overtaken by Google. Site Isolation has been a feature of Chrome since 2018.
How does Web Isolation Architecture work?
Web site isolation (Firefox Site Isolation) works by separating sites into process levels. Restricts one site from accessing another's memory space, something that was not possible in the previous architecture. This means that when you activate a new site, your system will create a new process for loading it.
Each of these processes is independent and does not share memory. This prevents malicious sites from accessing information on other pages.
The new feature provides security against the following threats:
- Violation of cookies between sites
- Spy on HTML, XML and JSON data
- Theft of passwords stored in the browser
- Utilization of licenses granted on another site
- Exploit DOM data from another site
How Firefox Site Isolation differs from the existing security model
In the previous model, Firefox created a fixed number of processes. He used to refer to eight processes for web content, two for semi-privileged content and four for graphic processes, multimedia and networking. This, however, allowed two or more different sites to run under the same process. So there was a chance that malicious websites would take advantage of the data on other pages.
However, the web isolation model fixes this problem by separating processes at runtime. This means that even if you load a malicious website, it will no longer be able to bypass its own process to access other page data.
Enable Firefox Site Isolation
You can enable the new feature in Firefox Nightly version from within
about: preferences # experimental
Check the Fission (Site Isolation) checkbox. If you are using a beta or the latest version of Firefox open the internal address about: config search for fission.autostart and set its value to true. You will need to restart Firefox for the changes to take effect.
Page isolation is still in its infancy, and Firefox may require additional CPU resources or become a bit slow.
Personally I have not had any problems with 50+ tabs open.