Polyfill supply chain attack hits 100K+ sites
sansec.io
The new Chinese owner of the popular Polyfill JS project injects malware into more than 100 thousand sites.

Archived link

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.

  • @danAEnglish
    120•3 days ago

    My favourite part is that the developers that currently own it said:

    Someone has maliciously defamed us. We have no supply chain risks because all content is statically cached

    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”.