At least a dozen organizations with domain names at domain registrar Squarespace saw their websites hijacked last week. Squarespace bought all assets of Google Domains a year ago, but many customers still haven’t set up their new accounts. Experts say malicious hackers learned they could commandeer any migrated Squarespace accounts that hadn’t yet been registered, merely by supplying an email address tied to an existing domain.

From the story:

"...an analysis released by security experts at Metamask and Paradigm finds the most likely explanation for what happened is that Squarespace assumed all users migrating from Google Domains would select the social login options — such “Continue with Google” or “Continue with Apple” — as opposed to the “Continue with email” choice.

Taylor Monahan, lead product manager at Metamask, said Squarespace never accounted for the possibility that a threat actor might sign up for an account using an email associated with a recently-migrated domain before the legitimate email holder created the account themselves.

“Thus nothing actually stops them from trying to login with an email,” Monahan told KrebsOnSecurity. “And since there’s no password on the account, it just shoots them to the ‘create password for your new account’ flow. And since the account is half-initialized on the backend, they now have access to the domain in question.”

https://krebsonsecurity.com/2024/07/researchers-weak-security-defaults-enabled-squarespace-domains-hijacks/

Researchers: Weak Security Defaults Enabled Squarespace Domains Hijacks – Krebs on Security

@briankrebs
> Squarespace assumed all users migrating from Google Domains would select the social login options — such “Continue with Google"

Yep, that sounds like humans to me, this was technically run by very few people who knew the details of the SSO integration and account migration process, and they thought "of course they will use the SSO option, wouldn't make sense to do anything else" and then went back to their mountain of tasks without giving it another thought.

@briankrebs If someone did think, "Hey, I should check the email-based registration flow" either they never got time to do it or it "worked" so they checked it off and moved on without thinking about the security implications if someone who is not the account owner started the workflow.