Will Shaw
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This alert finds sessions where a device-code flow produced multiple sign-in events (interactive + non-interactive), with mismatched user-agents or differing country/geolocation, for the same Session ID - a strong indicator of device-code phishing abuse.
Looks for:
Brute-forcing device code tokens
Token replay attempts
Malicious use of device code authentication across different devices or locations
Anomalous sign-in behaviour suggesting account compromise
Looks for:
Brute-forcing device code tokens
Token replay attempts
Malicious use of device code authentication across different devices or locations
Anomalous sign-in behaviour suggesting account compromise
This detection correlates suspicious device code authentication behaviour in Azure AD with a successful creation of a Windows Hello for Business (WHfB) credential within the same 24 hours.
Microsoft allows specific application and resource combinations (permitted by CA) access without a previously registered device. Even more, one of these combinations allows the registration of a device.
An access token issued for the Microsoft Authentication Broker application and the Intune Enrollment resource can be used to authenticate and initiate the device join process.
Therefore, an attacker can leverage the token to bypass CA, register device, and establish persistence. Once registered, attacker gets a Primary Refresh Token (PRT), valid for 90 days.
Attackers often push further to configure WHfB (Windows Hello For Business) on the registered device. WHfB issues TPM-backed, cryptographic credentials that Entra recognizes as a strong, phishing-resistant, passwordless authentication method.
Device registration unlocks persistence, but WHfB unlocks the ability to bypass stricter authentication-strength requirements.
Analysts: Check for IP mismatches, since in the Device Code authentication event we will see the victims IP, the WHfB registration event will contain the attackers IP.
Microsoft allows specific application and resource combinations (permitted by CA) access without a previously registered device. Even more, one of these combinations allows the registration of a device.
An access token issued for the Microsoft Authentication Broker application and the Intune Enrollment resource can be used to authenticate and initiate the device join process.
Therefore, an attacker can leverage the token to bypass CA, register device, and establish persistence. Once registered, attacker gets a Primary Refresh Token (PRT), valid for 90 days.
Attackers often push further to configure WHfB (Windows Hello For Business) on the registered device. WHfB issues TPM-backed, cryptographic credentials that Entra recognizes as a strong, phishing-resistant, passwordless authentication method.
Device registration unlocks persistence, but WHfB unlocks the ability to bypass stricter authentication-strength requirements.
Analysts: Check for IP mismatches, since in the Device Code authentication event we will see the victims IP, the WHfB registration event will contain the attackers IP.
This detection identifies cases where a successful device registration event in Azure AD occurs shortly after a successful Resource Owner Password Credentials (ROPC) authentication to Microsoft Intune Enrollment via the Microsoft Authentication Broker.
Microsoft allows specific application and resource combinations access without a previously registered device.
An access token issued for the Microsoft Authentication Broker application and the Intune Enrollment resource can be used to authenticate and initiate the device join process.
An attacker can leverage the token to bypass CA, register device, and establish persistence. Once registered, attacker gets a Primary Refresh Token (PRT), valid for 90 days.
The following query joins ROPC successful sign-ins, to successful device registrations. Registrations that occur soon after a ROPC event (2 days in this instance) could be an indicator of abuse.
Microsoft allows specific application and resource combinations access without a previously registered device.
An access token issued for the Microsoft Authentication Broker application and the Intune Enrollment resource can be used to authenticate and initiate the device join process.
An attacker can leverage the token to bypass CA, register device, and establish persistence. Once registered, attacker gets a Primary Refresh Token (PRT), valid for 90 days.
The following query joins ROPC successful sign-ins, to successful device registrations. Registrations that occur soon after a ROPC event (2 days in this instance) could be an indicator of abuse.