SFTPGo is an open source, event-driven file transfer solution. From 2.5.0 until 2.7.6, an authenticated user with copy permission can copy a source file denied by denied_patterns or outside allowed_patterns to an allowed destination name because file-pattern filters are evaluated only on the destination. The user can then read the denied file contents. Recursive directory copies can reproduce restricted contents under an allowed path, and the hide policy is bypassed because files that appear missing to stat and directory listings can still be copied. Home-directory boundaries, virtual-folder layout, per-directory permissions, access to other accounts, and administrative authorization remain enforced. This issue is fixed in 2.7.6.
Weakness
The product performs an authorization check when an actor attempts to access a resource or perform an action, but it does not correctly perform the check.
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.