Decidim: Verification admins can access supplied IDs from other organizations

Description

The verification admin mutation flow allows accessing, verifying, and rejecting participants records from another tenant.

Technical description

The verification admin controllers loads pending_authorization_id with a raw Authorization.find(...) and then authorizes the record without checking whether it belongs to current_organization.

Reproduction steps:

1. An org2 participant uploads their ID:

2. An admin from another organisation, in this case org1, is able to open the ID from org2 by opening request 35, e.g http://localhost:3001/admin/id_documents/pending_authorizations/35/confirmations/new

3. The admin then approves this request by looking up the ID in the picture (not shown in this image, but a real ID would expose this)

4. Now the request has been approved, which can be seen from the org2 participant authorizations page:

Impact

A tenant admin can access, reject or approve another tenant's id_documents requests.

Patches

See https://github.com/decidim/decidim/pull/16666

Workarounds

Disable the "Identity documents" verification

Reference

OWASP A01:2021 Broken Access Control

Credits

This issue was discovered in a security audit organized by the Decidim Association and made by Radically Open Security against Decidim financed by NGI.