- May 4, 2019
Microsoft have said that Outlook.com and Exchange Online were the only applications known to have been affected via the token forging technique, but Wiz Research has found that the compromised signing key was more powerful than it may have seemed, and was not limited to just those two services. Our researchers concluded that the compromised MSA key could have allowed the threat actor to forge access tokens for multiple types of Azure Active Directory applications, including every application that supports personal account authentication, such as SharePoint, Teams, OneDrive, customers’ applications that support the “login with Microsoft” functionality, and multi-tenant applications in certain conditions.
Our investigation of the security incident disclosed by Microsoft and CISA and attributed to Chinese threat actor Storm-0558, found that this incident seems to have a broader scope than originally assumed. Organizations using Microsoft and Azure services should take steps to assess potential impact.