CVE-2021-41238

Hangfire is an open source system to perform background job processing in a .NET or .NET Core applications. No Windows Service or separate process required. Dashboard UI in Hangfire.Core uses authorization filters to protect it from showing sensitive data to unauthorized users. By default when no custom authorization filters specified, LocalRequestsOnlyAuthorizationFilter filter is being used to allow only local requests and prohibit all the remote requests to provide sensible, protected by default settings. However due to the recent changes, in version 1.7.25 no authorization filters are used by default, allowing remote requests to succeed. If you are using UseHangfireDashboard method with default DashboardOptions.Authorization property value, then your installation is impacted. If any other authorization filter is specified in the DashboardOptions.Authorization property, the you are not impacted. Patched versions (1.7.26) are available both on Nuget.org and as a tagged release on the github repo. Default authorization rules now prohibit remote requests by default again by including the LocalRequestsOnlyAuthorizationFilter filter to the default settings. Please upgrade to the newest version in order to mitigate the issue. For users who are unable to upgrade it is possible to mitigate the issue by using the LocalRequestsOnlyAuthorizationFilter explicitly when configuring the Dashboard UI.

Weakness

The product does not perform an authorization check when an actor attempts to access a resource or perform an action.

Affected Software

Extended Description

Assuming a user with a given identity, authorization is the process of determining whether that user can access a given resource, based on the user’s privileges and any permissions or other access-control specifications that apply to the resource. When access control checks are not applied, users are able to access data or perform actions that they should not be allowed to perform. This can lead to a wide range of problems, including information exposures, denial of service, and arbitrary code execution.

Potential Mitigations

• Divide the product into anonymous, normal, privileged, and administrative areas. Reduce the attack surface by carefully mapping roles with data and functionality. Use role-based access control (RBAC) [REF-229] to enforce the roles at the appropriate boundaries.
• Note that this approach may not protect against horizontal authorization, i.e., it will not protect a user from attacking others with the same role.
• Use a vetted library or framework that does not allow this weakness to occur or provides constructs that make this weakness easier to avoid.
• For example, consider using authorization frameworks such as the JAAS Authorization Framework [REF-233] and the OWASP ESAPI Access Control feature [REF-45].
• For web applications, make sure that the access control mechanism is enforced correctly at the server side on every page. Users should not be able to access any unauthorized functionality or information by simply requesting direct access to that page.
• One way to do this is to ensure that all pages containing sensitive information are not cached, and that all such pages restrict access to requests that are accompanied by an active and authenticated session token associated with a user who has the required permissions to access that page.

Related Attack Patterns

• https://cwe.mitre.org/data/definitions/665.html

References

• https://github.com/HangfireIO/Hangfire/issues/1958
• https://github.com/HangfireIO/Hangfire/security/advisories/GHSA-7rq6-7gv8-c37h