FBI Raises Alarm About OAuth Consent Phishing Activity
The Federal Bureau of Investigation (FBI) has issued a warning about ongoing phishing activity involving a sophisticated technique known as OAuth consent phishing. Since late 2025, the FBI has observed malicious cyber actors using OAuth consent phishing in targeted attacks on prominent individuals, their family members, and personal acquaintances to gain persistent access to their accounts.
Similar to other forms of targeted phishing, the campaign involves impersonation of a trusted entity and tricks the victim into granting access to their account; however, this approach does not require the victim to disclose their username and password. The technique relies on OAuth, a commonly used authorization framework that allows websites and web applications to request access to a user’s account on another application, without exposing their login credentials.
With OAuth consent phishing, an attacker creates a malicious application and registers it with a legitimate OAuth provider. The application is configured with high-level privileges, such as the ability to access contacts, read and write emails, send emails on the user’s behalf, and more. The attacker then contacts the targeted individual via email or text and attempts to trick them into initiating the consent process.
In this campaign, the attackers typically impersonate publicly known personalities, government officials, journalists, and other high-profile individuals via a commercial messaging application (CMA). For instance, the individual is invited to take part in an event and must first verify their identity using the malicious but seemingly legitimate application.
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If the victim responds, they are presented with a legitimate permission request screen, such as for Microsoft 365, Google, or another legitimate cloud service. If the victim approves the request by clicking Allow, they provide their consent to the legitimate cloud service, which authorizes the malicious application to have the stated permissions through the provider’s authorization mechanism. The attacker is able to perform a range of malicious activities and access sensitive data without having to obtain the user’s password, and the technique bypasses multifactor authentication controls.
In practice, many users will not be aware that they have been successfully phished and will take no action. Should the victim smell a rat and change their password after granting access, the OAuth authentication token remains valid after the password change and will continue to provide the attacker with the previously granted permissions. The permissions must be revoked by removing the malicious app via the victim’s security settings.
The FBI advises users to be wary of this form of phishing and of any communications from unfamiliar phone numbers, accounts, or senders not in their contact list. Before taking any action in response to an unsolicited communication, users should first verify the identity of the sender and should only grant authorization to trusted applications. Even when the application is trusted, the requested permissions should be carefully assessed.
