GHSA-c7jf-qcx9-xxf8: 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 nerveshubweb 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 assignorgtoscope 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 nerveshub: 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. For the socket token: while signed in, copy the data-user-token attribute of the #console element, sign out, and within 24 hours connect a Phoenix socket client to /socket/websocket with that token. Joining user:console:identifier-<device identifier> succeeds.

Impact

A member who is removed from an organization or given a lower role keeps their old access through whatever they had open at the time, including device consoles and local shells that run commands on the device, until the page reloads or the socket disconnects. Anyone holding the dashboard's socket token taken from a page can open consoles as that user, within that user's current permissions, for up to 24 hours after they sign out.

Workarounds

After removing a member or lowering their role, restart the web nodes. That closes every open page and console, and each one is checked again when it reconnects. A socket token cannot be revoked before it expires short of changing SECRETKEYBASE, which signs everyone out.