Conference:  Defcon 31

Authors: nyxgeek hacker at TrustedSec

2023-08-01

Microsoft Azure is ripe with user information disclosures. We are going to look at weaponizing these disclosures by performing data collection at a large scale against OneDrive, Teams, and Graph. OneDrive and Teams present silent enumeration methods, requiring no logon attempts and creating no logs. This enables enumeration at a massive scale against the biggest corporations, educational instututes, and government entities in the world. Over the last 1.5 years I have enumerated over 20m users. We will explore the techniques used and the data that was collected, including Azure adoption rates and analysis of username formats. Microsoft Teams suffers from information dislcosure due to default settings allowing users to see the online presence of others. An undocumented, unauthenticated Microsoft Teams Presence lookup trick will be shared, which enables easy unauthenticated enumeration of the online Teams Presence of users at many organizations. To demonstrate this we will monitor approximately 100,000 Microsoft employees' online presence and any out-of-office messages that are stored. Finally, Azure supports Guest users, allowing two companies to collaborate on a project. I will unveil a method of identifying Azure Guest users at other tenants. In this way, hidden corporate relationships can be revealed.

Conference:  Defcon 31

Authors: Dr Nestori Syynimaa Senior Principal Security Researcher, Secureworks

2023-08-01

Microsoft SharePoint Online (SPO) is a cloud-based service that helps organizations share and manage content. It is also used as backend file storage for other Microsoft online services, such as Microsoft 365 Groups, OneDrive, and Teams. Microsoft offers tools such as Migration Manager and SharePoint Migration Tool (SPMT) to ease migrating files from on-premises file servers to SPO, OneDrive, and Teams. Both tools use the same background APIs to perform the data migration. Technically, the migration is leveraging the built-in Granular Backup feature of on-premises SharePoint, which allows exporting and importing individual SharePoint sites and lists. The Granular Backup feature is not available in SharePoint Online. In this talk, I'll show how threat actors can leverage SPO migration APIs to break the integrity of all Microsoft online services that use SPO as storage. Threat actors can spoof new content and tamper with existing content, and inject custom code to perform XSS attacks. This, in turn, enables elevation-of-privilege attacks to all Microsoft Online services, including Azure Active Directory. And all this as a regular user.