CVE-2023-41046

XWiki Platform is a generic wiki platform offering runtime services for applications built on top of it. It is possible in XWiki to execute Velocity code without having script right by creating an XClass with a property of type TextArea and content type VelocityCode or VelocityWiki. For the former, the syntax of the document needs to be set the xwiki/1.0 (this syntax doesnt need to be installed). In both cases, when adding the property to an object, the Velocity code is executed regardless of the rights of the author of the property (edit right is still required, though). In both cases, the code is executed with the correct context author so no privileged APIs can be accessed. However, Velocity still grants access to otherwise inaccessible data and APIs that could allow further privilege escalation. At least for VelocityCode, this behavior is most likely very old but only since XWiki 7.2, script right is a separate right, before that version all users were allowed to execute Velocity and thus this was expected and not a security issue. This has been patched in XWiki 14.10.10 and 15.4 RC1. Users are advised to upgrade. There are no known workarounds.

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/xwiki/xwiki-platform/commit/edc52579eeaab1b4514785c134044671a1ecd839
• https://github.com/xwiki/xwiki-platform/security/advisories/GHSA-m5m2-h6h9-p2c8
• https://jira.xwiki.org/browse/XWIKI-20847
• https://jira.xwiki.org/browse/XWIKI-20848