New analysis has pulled again the curtain on a “deficiency” in Google’s “Sign up with Google” authentication stream that exploits a quirk in area possession to realize entry to delicate knowledge.
“Google’s OAuth login does not defend towards somebody buying a failed startup’s area and utilizing it to re-create electronic mail accounts for former workers,” Truffle Safety co-founder and CEO Dylan Ayrey stated in a Monday report.
“And when you cannot entry outdated electronic mail knowledge, you should use these accounts to log into all of the totally different SaaS merchandise that the group used.”
The San Francisco-based firm stated the problem has the potential to place thousands and thousands of American customers’ knowledge in danger just by buying a defunct area related to a failed startup and gaining unauthorized entry to outdated worker accounts associated to varied purposes like OpenAI ChatGPT, Slack, Notion, Zoom, and even HR programs.
“Essentially the most delicate accounts included HR programs, which contained tax paperwork, pay stubs, insurance coverage info, social safety numbers, and extra,” Ayrey stated. “Interview platforms additionally contained delicate details about candidate suggestions, affords, and rejections.”
OAuth, brief for open authorization, refers to an open customary for entry delegation, permitting customers to grant web sites or purposes entry to their info on different web sites with out having to present their passwords. That is completed by making use of an entry token to confirm the person’s identification and permit the service to entry the useful resource the token is meant for.
When “Sign up with Google” is used to check in to an software comparable to Slack, Google sends the service a set of claims concerning the person, together with their electronic mail handle and the hosted area, which may then be utilized to log customers into their accounts.
This additionally signifies that if a service is solely counting on these items of data to authenticate customers, it additionally opens the door to a state of affairs the place area possession modifications may permit an attacker to regain entry to outdated worker accounts.
Truffle additionally identified Google’s OAuth ID token features a distinctive person identifier – the sub declare – that would theoretically stop the issue, however that has been discovered to be unreliable. It is value noting that Microsoft’s Entra ID tokens embody the sub or oid claims to retailer an immutable worth per person.
Whereas Google initially responded to the vulnerability disclosure by stating that it’s supposed habits, it has since re-opened the bug report as of December 19, 2024, awarding Ayrey a bounty of $1,337. It has additionally certified the problem as an “abuse-related methodology with excessive affect.”
Within the meantime, there aren’t any protections that downstream software program suppliers can take to guard towards the vulnerability in Google’s OAuth implementation. The Hacker Information has reached out to Google for additional remark, and we’ll replace the story if we hear again.
“As a person, as soon as you have been off-boarded from a startup, you lose your potential to guard your knowledge in these accounts, and you’re topic to no matter destiny befalls the way forward for the startup and area,” Ayrey stated. “With out immutable identifiers for customers and workspaces, area possession modifications will proceed to compromise accounts.”
