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.
What’s the malware do?
Frustrating that the article doesn’t specify and simply links to a different Github page which doesn’t clearly specify the problem either.
I have to assume the site’s article was dynamically generated, without any actual tech journalist doing the reporting. The byline is “Sansec Forensics Team” which doesn’t even link out to the group. Also, the “Chinese Company” isn’t named either it the article or the references, which is incredibly shoddy reporting. The archive link is dead.
This whole page is indicative of the failed state of tech journalism. A genuinely explosive story but its so threadbare and vague that it becomes meaningless.
The site is Sansec. They uncovered it. They also specify how the malware redirects users to sports betting sites.