Crooks Bypassed Google's Email Verification To Create Workspace Accounts, Access 3rd-Party Services

Brian Krebs writes via KrebsOnSecurity: Google says it recently fixed an authentication weakness that allowed crooks to circumvent the email verification required to create a Google Workspace account, and leverage that to impersonate a domain holder at third-party services that allow logins through Google's "Sign in with Google" feature. [...] Google Workspace offers a free trial that people can use to access services like Google Docs, but other services such as Gmail are only available to Workspace users who can validate control over the domain name associated with their email address. The weakness Google fixed allowed attackers to bypass this validation process. Google emphasized that none of the affected domains had previously been associated with Workspace accounts or services. "The tactic here was to create a specifically-constructed request by a bad actor to circumvent email verification during the signup process," [said Anu Yamunan, director of abuse and safety protections at Google Workspace]. "The vector here is they would use one email address to try to sign in, and a completely different email address to verify a token. Once they were email verified, in some cases we have seen them access third party services using Google single sign-on." Yamunan said none of the potentially malicious workspace accounts were used to abuse Google services, but rather the attackers sought to impersonate the domain holder to other services online.

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