2FAuth: Reverse Proxy Guard Auto-Creates Users With Admin Promotion From Unauthenticated Header Value

Summary

2FAuth is a web app to manage Two-Factor Authentication (2FA) accounts and generate their security codes. Prior to 8.0.0, when AUTHENTICATION_GUARD=reverse-proxy-guard accepts authentication headers from a client that did not pass through a trusted proxy, RemoteUserProvider::retrieveById() creates an account for an unknown REMOTE_USER, promotes the first created account to administrator, and synchronizes the account email from the configured mail header. An unauthenticated remote client can therefore create an administrator on a fresh instance or impersonate and redirect email for a known account, exposing 2FA secrets and administrative functions. This issue is fixed in version 8.0.0.

Remediation

1. Inventory every Bubka 2FAuth deployment, including staging.
2. No fixed version appears in the public sources yet. Check the references below and the vendor directly.

References

• Referencehttps://github.com/Bubka/2FAuth/commit/43873cbfba445926c7008b4291eeee67752af9e8
• Referencehttps://github.com/Bubka/2FAuth/commit/8a4c395cac97f8b70b4a822639a6ad8a816f927c
• Referencehttps://github.com/Bubka/2FAuth/commit/d9e58ac4a63fbd8a073e423567881c81a87915de
• Referencehttps://github.com/Bubka/2FAuth/releases/tag/v8.0.0
• Referencehttps://github.com/Bubka/2FAuth/security/advisories/GHSA-r9xx-45m8-mw24