GHSA-vcwh-pff9-64cc RustFS has IAM Incorrect Authorization in ImportIam that Allows Privilege Escalation

• crates.io rustfs: < 1.0.0-alpha.79 → fixed in 1.0.0-alpha.79

Summary The `ImportIam` admin API validates permissions using `ExportIAMAction` instead of `ImportIAMAction`, allowing a principal with *export-only* IAM permissions to perform *import* operations. Since importing IAM data performs privileged write actions (creating/updating users, groups, policies, and service accounts), this can lead to unauthorized IAM modification and privilege escalation. --- Details In `ImportIam`, the authorization check is implemented as follows: ```rust validate_admin_request( &req.headers, &cred, owner, false, vec![Action::AdminAction(AdminAction::ExportIAMAction)], ).await?; ``` However, this code resides in the Import IAM operation (`struct ImportIam {}`), which performs state-changing IAM writes. The expected behavior is to validate against `AdminAction::ImportIAMAction` (or an equivalent import-specific admin action), not `ExportIAMAction`. --- PoC Prerequisites 1. A RustFS deployment with IAM enabled. 2. An IAM user or role that has Export IAM permission but does not have Import IAM or full admin permissions. 3. Access credentials for that user. Steps 1. Create or obtain an IAM principal with permission equivalent to: ``` AdminAction::ExportIAMAction ``` and without Import IAM privileges. 2. Prepare a valid IAM import ZIP archive containing, for example: • A new policy granting administrative permissions • A user or service account bound to that policy 3. Send a request to the Import IAM endpoint (the same endpoint handled by `ImportIam::call`), authenticating with the export-only credentials. 4. Observe that: • The request passes authorization. • IAM entities from the archive are created or modified successfully. Expected Result • The request should be rejected with an authorization error (e.g., AccessDenied). Actual Result • The request succeeds, and IAM state is modified.