The polyfill.js is a popular open source library to support older browsers. 100K+ sites embed it using the cdn.polyfill.io domain. Notable users are JSTOR, Intuit and World Economic Forum. However, in February this year, a Chinese company bought the domain and the Github account. Since then, this domain was caught injecting malware on mobile devices via any site that embeds cdn.polyfill.io. Any complaints were quickly removed (archive here) from the Github repository.
My favourite part is that the developers that currently own it said:
https://github.com/polyfillpolyfill/polyfill-service/issues/2890#issuecomment-2191461961
Completely missing the point that they are the supply chain risk, and the fact that malicious code was already detected in their system (to the point where Google started blocking ads for sites that loaded polyfill .io scripts.
We don’t even know who they are - the repo is owned by an anonymous account called “polyfillpolyfill”, and that comment comes from another anonymous account “polyfillcust”.
Pollyfilladmin
Pollyfillpassword
Pollyfillnoteventryn
I’m not into JS stuff, but when I read that google is blocking ads, shit must be flowing in gargantuan amounts…