Clicking 'Allow' on a Google and Microsoft permission screens could give hackers access to your entire account, FBI warns

FBI warns of rising OAuth consent phishing attacks exploiting legitimate app permissions Victims tricked into granting malicious apps access, enabling email reading and sending Password changes don’t help; users must revoke tokens in app security settings Hackers found a way to access your data, read your messages, and even send emails to your contacts, without ever needing your password or other login credentials.

All they need from you is a single click on a completely legitimate, well-known platform.

The technique is called “OAuth consent phishing”.

It’s been around for more than a year and it’s gotten popular to a point where even the FBI is taking note.

Earlier this week, the law enforcement agency issued a new public service announcement, via its Internet Crime Complaint Center (IC3), warning Americans about the threat.

OAuth (Open Authorization) is an internet standard that allows users to give apps access to their account on another service, without giving the app their password for that service.

For example, when users install a new app, they have the “Continue with Google” option.

When they click it, they are asked if they allow the app to access their email.

If they approve, Google gives that app a special access token, which allows the app to access the user’s Google account without ever seeing the password.

Pulling off an OAuth attack So, to pull off an OAuth attack, the threat actor must first trick Google (or Microsoft, or any other company providing the service) and get their (malicious) app registered on the platform.

Then they would reach out to their target via instant messaging, while impersonating government officials, media, and other publicly known personalities, and sharing a link to what appears to be a document.

The link redirects the victim to a legitimate service (for example, Google), where they are asked to grant permissions to the malicious app.

If they approve, the attackers gain access to their email accounts with which they can do almost anything.

To make matters worse, simply changing the password does not fix the issue.