Mozilla adds option on Firefox to block hidden cryptomining scripts

By Mateen Dalal

The browser would leverage a new blacklist of websites which are recognized as using scripts for cryptomining or fingerprinting

Reports suggest that Firefox’s upcoming release would provide users the option to block two increasingly common nuisances on the web, cryptomining scripts and browser fingerprinting.

Mozilla has recently revealed that Firefox Beta 67 and Firefox Nightly 68 will include protection against both cryptomining scripts and fingerprinting threats. This open source web browser would leverage a new blacklist of websites which are recognized as using scripts for either purpose. The blacklist was composed by Disconnect, a VPN maker which is known for its anti-tracking efforts.

Apparently, these types of scripts are neither helpful nor beneficial to browser users. Through fingerprinting, advertising software silently track users around the web and gain from the activity and interests of the user. On the other hand, freeloading opportunists have found it lucrative to plant cryptomining JavaScript on websites and secretly scrounge CPU of a visitor to mine cryptocurrency.

Web-based cryptomining accelerated after the launch of the JavaScript-based Coinhive, which was established with the purpose to challenge the model of online advertising business. But it was rapidly adapted for cryptojacking via browsers so that it mines for cryptocurrency on behalf of someone else.

Sources familiar with the matter informed that Mozilla is implementing a multi-pronged approach to fingerprinting termed as Letterboxing. It aims to prevent a technique which is used to tag a browser, such as measuring window size of a browser, for continued tracking across websites without the help of cookies. The second part is a blacklist of sites that are known to utilize fingerprinting scripts and sites which use cryptomining scripts.

Supposedly, the script-blocking feature is now becoming a part of Firefox's 'Content Blocking' settings that are available within the 'Privacy and Security' tab in Preferences.

In 'Content Blocking', Firefox users can check boxes for blocking either or both Fingerprinters and Cryptominers. Once it is enabled, Firefox will block any type of scripts that have been acknowledged by privacy tool Disconnect to participate in fingerprinting or cryptomining, sources mentioned.