CVE-2024-38537

Fides is an open-source privacy engineering platform. `fides.js`, a client-side script used to interact with the consent management features of Fides, used the `polyfill.io` domain in a very limited edge case, when it detected a legacy browser such as IE11 that did not support the fetch standard. Therefore it was possible for users of legacy, pre-2017 browsers who navigate to a page serving `fides.js` to download and execute malicious scripts from the `polyfill.io` domain when the domain was compromised and serving malware. No exploitation of `fides.js` via `polyfill.io` has been identified as of time of publication. The vulnerability has been patched in Fides version `2.39.1`. Users are advised to upgrade to this version or later to secure their systems against this threat. On Thursday, June 27, 2024, Cloudflare and Namecheap intervened at a domain level to ensure `polyfill.io` and its subdomains could not resolve to the compromised service, rendering this vulnerability unexploitable. Prior to the domain level intervention, there were no server-side workarounds and the confidentiality, integrity, and availability impacts of this vulnerability were high. Clients could ensure they were not affected by using a modern browser that supported the fetch standard.

Fides is an open-source privacy engineering platform. `fides.js`, a client-side script used to interact with the consent management features of Fides, used the `polyfill.io` domain in a very limited edge case, when it detected a legacy browser such as IE11 that did not support the fetch standard. Therefore it was possible for users of legacy, pre-2017 browsers who navigate to a page serving `fides.js` to download and execute malicious scripts from the `polyfill.io` domain when the domain was compromised and serving malware. No exploitation of `fides.js` via `polyfill.io` has been identified as of time of publication. The vulnerability has been patched in Fides version `2.39.1`. Users are advised to upgrade to this version or later to secure their systems against this threat. On Thursday, June 27, 2024, Cloudflare and Namecheap intervened at a domain level to ensure `polyfill.io` and its subdomains could not resolve to the compromised service, rendering this vulnerability unexploitable. Prior to the domain level intervention, there were no server-side workarounds and the confidentiality, integrity, and availability impacts of this vulnerability were high. Clients could ensure they were not affected by using a modern browser that supported the fetch standard.

### Note On Thursday, June 27, 2024, Cloudflare and Namecheap intervened at a domain level to ensure `polyfill.io` and its subdomains could not resolve to the compromised service, rendering this vulnerability **unexploitable**. The following sections describe this vulnerability prior to the domain level intervention, when it was still exploitable. ### Impact `fides.js`, a client-side script used to interact with the consent management features of Fides, used the `polyfill.io` domain in a very limited edge case, when it detected a legacy browser such as IE11 that did not support the fetch standard. On June 25th, 2024, Sansec published the following regarding the `polyfill.io` domain. > The polyfill.js is a popular open source library to support older browsers. 100K+ sites embed it using the cdn.polyfill.io domain... 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. Therefore it was possible for users of legacy, pre-2017 browsers who navigate to a page serving `fides.js` to download and execute malicious scripts from the compromised domain. No exploitation of `fides.js` via `polyfill.io` has been identified at this time, but other script developers who use `https://cdn.polyfill.io/v2/polyfill.min.js` have reported redirects to malicious websites. ### Patches The vulnerability has been patched in Fides version `2.39.1`. Users are advised to upgrade to this version or later to secure their systems against this threat. ### Workarounds Prior to the domain level intervention, there were no server-side workarounds and the confidentiality, integrity, and availability impacts of this vulnerability were high. Clients could ensure they were not affected by using a modern browser that supported the fetch standard. caniuse.com/fetch estimates that 97.52% of browser users use a browser that supports the fetch standard. ### References - https://sansec.io/research/polyfill-supply-chain-attack - https://github.com/ethyca/fides/pull/5026/ - https://fetch.spec.whatwg.org/

### Note On Thursday, June 27, 2024, Cloudflare and Namecheap intervened at a domain level to ensure `polyfill.io` and its subdomains could not resolve to the compromised service, rendering this vulnerability **unexploitable**. The following sections describe this vulnerability prior to the domain level intervention, when it was still exploitable. ### Impact `fides.js`, a client-side script used to interact with the consent management features of Fides, used the `polyfill.io` domain in a very limited edge case, when it detected a legacy browser such as IE11 that did not support the fetch standard. On June 25th, 2024, Sansec published the following regarding the `polyfill.io` domain. > The polyfill.js is a popular open source library to support older browsers. 100K+ sites embed it using the cdn.polyfill.io domain... 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. Therefore it was possible for users of legacy, pre-2017 browsers who navigate to a page serving `fides.js` to download and execute malicious scripts from the compromised domain. No exploitation of `fides.js` via `polyfill.io` has been identified at this time, but other script developers who use `https://cdn.polyfill.io/v2/polyfill.min.js` have reported redirects to malicious websites. ### Patches The vulnerability has been patched in Fides version `2.39.1`. Users are advised to upgrade to this version or later to secure their systems against this threat. ### Workarounds Prior to the domain level intervention, there were no server-side workarounds and the confidentiality, integrity, and availability impacts of this vulnerability were high. Clients could ensure they were not affected by using a modern browser that supported the fetch standard. caniuse.com/fetch estimates that 97.52% of browser users use a browser that supports the fetch standard. ### References - https://sansec.io/research/polyfill-supply-chain-attack - https://github.com/ethyca/fides/pull/5026/ - https://fetch.spec.whatwg.org/

Fides es una plataforma de ingeniería de privacidad de código abierto. `fides.js`, un script del lado del cliente utilizado para interactuar con las funciones de gestión de consentimiento de Fides, utilizó el dominio `polyfill.io` en un caso límite muy limitado, cuando detectó un navegador heredado como IE11 que no admitía el estándar de recuperación. Por lo tanto, era posible que los usuarios de navegadores heredados anteriores a 2017 que navegaban a una página que servía `fides.js` descargaran y ejecutaran scripts maliciosos desde el dominio `polyfill.io` cuando el dominio estaba comprometido y servía malware. No se ha identificado ninguna explotación de `fides.js` a través de `polyfill.io` al momento de la publicación. La vulnerabilidad ha sido parcheada en la versión `2.39.1` de Fides. Se recomienda a los usuarios que actualicen a esta versión o posterior para proteger sus sistemas contra esta amenaza. El jueves 27 de junio de 2024, Cloudflare y Namecheap intervinieron a nivel de dominio para garantizar que `polyfill.io` y sus subdominios no pudieran resolver el servicio comprometido, haciendo que esta vulnerabilidad no se pudiera explotar. Antes de la intervención a nivel de dominio, no había workarounds en el lado del servidor y los impactos de esta vulnerabilidad en la confidencialidad, integridad y disponibilidad eran altos. Los clientes podían asegurarse de no verse afectados utilizando un navegador moderno que admitiera el estándar de recuperación.