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Incomplete authorization in multi-tenant deployments

Critical
bmc-msft published GHSA-q5vh-6whw-x745 Aug 13, 2021

Package

pip onefuzz (pip)

Affected versions

> 2.12.0

Patched versions

2.31.0

Description

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:

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:

Severity

Critical

CVSS overall score

This score calculates overall vulnerability severity from 0 to 10 and is based on the Common Vulnerability Scoring System (CVSS).
/ 10

CVSS v3 base metrics

Attack vector
Network
Attack complexity
Low
Privileges required
None
User interaction
None
Scope
Changed
Confidentiality
High
Integrity
High
Availability
Low

CVSS v3 base metrics

Attack vector: More severe the more the remote (logically and physically) an attacker can be in order to exploit the vulnerability.
Attack complexity: More severe for the least complex attacks.
Privileges required: More severe if no privileges are required.
User interaction: More severe when no user interaction is required.
Scope: More severe when a scope change occurs, e.g. one vulnerable component impacts resources in components beyond its security scope.
Confidentiality: More severe when loss of data confidentiality is highest, measuring the level of data access available to an unauthorized user.
Integrity: More severe when loss of data integrity is the highest, measuring the consequence of data modification possible by an unauthorized user.
Availability: More severe when the loss of impacted component availability is highest.
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:H/I:H/A:L

CVE ID

CVE-2021-37705