Improper session invalidation keeps removed or demoted members' open pages and device consoles working at their old role

Summary

Improper Session Invalidation vulnerability in the dashboard pages, device console and local shell channels in nerves-hub nerves_hub_web allows an organization member who is removed or given a lower role to keep acting at their old role through anything they had open at the time. The dashboard reads the member's role once when a page mounts, in the assign_org_to_scope hook of NervesHubWeb.Auth, and the console, local shell and device event stream channels check membership once at join. Removing a member or changing their role tells none of them, so open pages keep carrying out actions and open consoles keep running commands on the device until the page reloads or the socket disconnects.

The dashboard also opens consoles over NervesHubWeb.UserSocket with a token that holds only the user's id, is accepted for 24 hours, and is not revoked by signing out, which disconnects only the session's LiveViews. Whoever holds a token taken from a page can open consoles as that user, within the user's current membership, until it expires.

This issue affects nerves_hub: from 1.0.0 before 2.5.3.

Proof of concept

1. In an organization, A is an admin and B has the manage role. B opens a device's page and its Console tab.
2. A removes B from the organization on the organization's Users page, or lowers B's role to view.
3. Without reloading, B's open page still carries out actions and B's console still accepts input, until B reloads the page or the socket disconnects.
   4.…