A Missing Authorization vulnerability was identified in GitHub Enterprise Server that allowed an attacker to upload unauthorized content to another user’s repository migration export due to a missing authorization check in the repository migration upload endpoint. By supplying the migration identifier, an attacker could overwrite or replace a victim’s migration archive, potentially causing victims to download attacker-controlled repository data during migration restores or automated imports. An attacker would require authentication to the victims GitHub Enterprise Server instance. This vulnerability affected all versions of GitHub Enterprise Server prior to 3.20 and was fixed in versions 3.19.2, 3.18.5, 3.17.11, 3.16.14, 3.15.18, 3.14.23. This vulnerability was reported via the GitHub Bug Bounty program.
Weakness
The product does not perform an authorization check when an actor attempts to access a resource or perform an action.
Affected Software
| Name | Vendor | Start Version | End Version |
|---|---|---|---|
| Enterprise_server | Github | * | 3.14.23 (excluding) |
| Enterprise_server | Github | 3.15.0 (including) | 3.15.18 (excluding) |
| Enterprise_server | Github | 3.16.0 (including) | 3.16.14 (excluding) |
| Enterprise_server | Github | 3.17.0 (including) | 3.17.11 (excluding) |
| Enterprise_server | Github | 3.18.0 (including) | 3.18.5 (excluding) |
| Enterprise_server | Github | 3.19.0 (including) | 3.19.2 (excluding) |
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
References
- https://docs.github.com/en/enterprise-server@3.14/admin/release-notes#3.14.23
- https://docs.github.com/en/enterprise-server@3.15/admin/release-notes#3.15.18
- https://docs.github.com/en/enterprise-server@3.16/admin/release-notes#3.16.14
- https://docs.github.com/en/enterprise-server@3.17/admin/release-notes#3.17.11
- https://docs.github.com/en/enterprise-server@3.18/admin/release-notes#3.18.5
- https://docs.github.com/en/enterprise-server@3.19/admin/release-notes#3.19.2