Security News > 2021 > January > SVR Attacks on Microsoft 365

Steal the Active Directory Federation Services token-signing certificate and use it to forge tokens for arbitrary users.

This would allow the attacker to authenticate into a federated resource provider as any user, without the need for that user's password or their corresponding multi-factor authentication mechanism.

Modify or add trusted domains in Azure AD to add a new federated Identity Provider that the attacker controls.

This would allow the attacker to forge tokens for arbitrary users and has been described as an Azure AD backdoor.

Compromise the credentials of on-premises user accounts that are synchronized to Microsoft 365 that have high privileged directory roles, such as Global Administrator or Application Administrator.

Backdoor an existing Microsoft 365 application by adding a new application or service principal credential in order to use the legitimate permissions assigned to the application, such as the ability to read email, send email as an arbitrary user, access user calendars, etc.

News URL

https://www.schneier.com/blog/archives/2021/01/svr-attacks-on-microsoft-365.html