HYAS Protects Against Polyfill.io Supply Chain Attack with DNS Safeguards

Weekly Threat Intelligence Report

Date: June 28, 2024

Prepared by: David Brunsdon, Threat Intelligence - Security Engineer, HYAS

Recently a Chinese company named Funnull purchased the domain (polyfill.io) and github of an open source javascript library used in over 100,000 websites.


Polyfill allows website creators to maintain support for a variety of older browser types, however its operation has changed to include redirecting mobile devices to sports betting using a fake google analytics domain (www.googie-anaiytics.com).

For users of HYAS Protect, HYAS disables DNS resolutions that would lead to these redirects and other potential compromises. DNS is the ideal place to block potentially malicious CDNs, like we have here. Other vendors, such as Cloudflare, have also responded by rewriting any Polyfill code to redirect to their own cached copy of the javascript library. Today, Namecheap, the provider of the domain, has taken it over and removed the A record and completely disabling the threat.

Oddly enough, Funnull has denied the existence of any supply chain attack, and has registered a new domain, polyfill[.]com which is described on the web page as “A free CDN for open source projects.”

Supply chain attacks through open source products remain a serious attack vector. In this situation the original maintainer sold control to another company that appears to have a malicious intent. Situations like these have the potential to impact a large number of individuals and organizations and this type of potential compromise should always be considered a part of an organization's threat model.

HYAS threat intelligence will continue to monitor the situation and will adapt our security solution as required.

Security analysts interested in researching their own network telemetry for compromise should focus on outbound connections to the following domains:


The new domain, polyfill[.]com has not been known to be used with any malicious behavior but the concern remains about how it could be used in the future, as it’s still under the control of Funnull, who has denied the existence of the supply chain attack. 

As always, the HYAS Threat Intelligence team is at the ready. If you’d like to speak with one of our experts, please reach out to us, and we’d be happy to help. 

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