Impact

Starting with OneFuzz 2.12.0 or greater, an incomplete authorization check allows an authenticated user from any Azure Active Directory tenant to make authorized API calls to a vulnerable OneFuzz instance.

To be vulnerable, a OneFuzz deployment must be:

• Version 2.12.0 or greater
• Deployed with the non-default --multi_tenant_domain option

This can result in read/write access to private data such as:

• Software vulnerability and crash information
• Security testing tools
• Proprietary code and symbols

Via authorized API calls, this also enables tampering with existing data and unauthorized code execution on Azure compute resources.

Patches

This issue is resolved starting in release 2.31.0, via the addition of application-level check of the bearer token's issuer against an administrator-configured allowlist.

Workarounds

Users can restrict access to the tenant of a deployed OneFuzz instance < 2.31.0 by redeploying in the default configuration, which omits the --multi_tenant_domain option.

References

You can find an overview of the Microsoft Identity Platform here. This vulnerability applies to the multi-tenant application pattern, as described here.

For more information

If you have any questions or comments about this advisory:

• Open an issue in OneFuzz
• Email us at fuzzing@microsoft.com