Eight eMudhra intermediate CAs compromised

The private keys of eight intermediate certificate authorities operated by eMudhra have been compromised. These certificates chain to roots trusted by the Mozilla, Microsoft, Apple and Chrome root programs, as well as by many downstream trust stores.

How we know

To prove the compromise, the reporter, who signed as Wayne, used each of the eight intermediates' private keys to sign the message "We have a problem here - Wayne" and delivered it to the root program teams on 17 October. The proof.zip archive contains the message plus, for each intermediate, its certificate, public key and signature; all of it can be verified with OpenSSL.

Consequences

Anyone holding the private key of any affected intermediate can impersonate any website or service. That is the core danger: trusting such a CA means trusting forged certificates.

What has been done

The certificates have been blocked in Firefox and Chrome since 17 October, on Apple devices since the 19^th, and in Microsoft since the 20^th. Vendors are pushing revocation through their own channels — OneCRL, CRLite and CRLSets. The CA itself has revoked the compromised intermediates. The issue was responsibly disclosed to downstream trust stores on 19 October.

Many clients, however, do not consume revocation data and will keep trusting these CAs until software updates arrive.

For users and developers

Ordinary users are advised to update their browsers and operating systems as soon as possible. For developers, patched versions are already out for Ubuntu ca-certificates, Go, Electron, Python certifi, Rust (rustls-webpki and webpki-roots), Homebrew ca-certificates, NSS and uv; fixes for Node.js and Composer ca-bundle are still pending.

One subtlety stands out: the macOS built-in /usr/bin/curl verifies certificates against /etc/ssl/cert.pem without checking revocation, and that file has not been updated. The authors provide commands for manually distrusting the affected roots on macOS, on various Linux distributions and on NetBSD — with the caveat that this is not recommended for ordinary users.

The detailed site was published by Dennis Jackson, with the source available on GitHub.

Source: Hacker News