Hackers obtain counterfeit TLS certificates for Google and other large services

From the article:

The attackers launched a series of attacks on the .gh, .sl, and .as country code top-level domains (ccTLDs) and then modified authoritative DNS records for selected domains within those namespaces. By controlling those DNS records, the attackers were able to pass automated domain control validation checks and obtain unauthorized certificates for “several Google domains” and “several leading global brands and widely used online services.” Google said it updated Chrome to block all certificates it identified as unauthorized, and worked with the issuing certification authorities to ensure the unauthorized certificates for Google properties were revoked.

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Google didn’t identify the affected domains it owns or name any of the other organizations whose domains were affected. While noting that Chrome users do not need to take any action to be protected, Google cautioned domain owners not to rely solely on browser-side interventions to protect their users. The company is advising domain owners to monitor certificate transparency logs for unexpected certificate issuance across their domains and to publish restrictive Certification Authority Authorization DNS records to prevent attackers from reusing cached validation data after DNS control is restored.

“While Chrome took steps during these incidents to identify and block suspected unauthorized certificates across the affected ccTLDs, browser-side intervention should not be relied on to protect your users,” Google said. “Due to the complexity of DNS hijacks, we cannot guarantee that our analysis identified every affected domain, nor do Chrome interventions reliably protect non-Chrome users.”

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Google noted that the incident didn’t involve the compromise of the infrastructure of any of the affected domain owners and that certificate authorities followed all requirements. With control of the three ccTLDs, the attackers were able to change the IP addresses of a selected list of websites. With the ability to send and receive traffic on those sites, the attackers were able to modify authoritative DNS records and nameserver delegations for selected domains, allowing them to pass industry validation checks requiring an applicant to prove control of the domain.