# The Bitcoin RPC proxy that stayed open after it was fixed

**Status:** code fix committed (`f6b5245b`); on-node verification recorded below.
**Found:** 2026-08-02, archi-dev-box, while verifying `a05956c4` instead of assuming it.
**Severity:** critical on any affected node — unauthenticated control of Bitcoin Core RPC
through a proxy that injects the node's own credentials.

## Why this document exists

`a05956c4` closed two unauthenticated endpoints on the wallet UI ports. Its commit message
stated:

> The nginx template is `include_str!`'d and re-rendered on every reconcile pass, so this
> ships atomically with the binary.

That is true for most nodes and false for a specific, silent, and not-rare state. The half
that landed correctly (LND) made the half that did not (Bitcoin RPC) *harder* to notice,
because a spot check of the LND endpoint returns a clean `401` and reads as "patched".

## What was observed

Node running the fixed binary (installed 17:21, contains the new template — `auth_request`
present in the binary at 4 occurrences). All probes from the node's own LAN address, no
cookies, no credentials:

| Probe | Result |
|---|---|
| `GET http://192.168.63.240:18083/lnd-connect-info` | `401`, 24 bytes, `{"error":"Unauthorized"}` — **closed** |
| `POST http://192.168.63.240:8334/bitcoin-rpc/` (`getblockcount`) | `200` — `{"result":960774,"error":null}` — **OPEN** |
| `OPTIONS http://192.168.63.240:8334/bitcoin-rpc/` | `204` with `Access-Control-Allow-Origin: *` — **OPEN** |

The rendered config on disk, `/var/lib/archipelago/bitcoin-ui/nginx.conf`, was dated
**2026-06-30** — the pre-fix version, with no `auth_request` and with the wildcard CORS
header the fix removes.

## Root cause

Three facts have to be true at once, and on this node they were:

1. `bitcoin-ui` is listed in the node's durable `user-uninstalled` marker
   (`/var/lib/archipelago/user-uninstalled.json`).
2. `reconcile_app` returns on that marker (`prod_orchestrator.rs:1956`) **before** reaching
   `run_pre_start_hooks`, which is the only thing that renders the nginx config.
3. The container keeps running anyway, because it is owned by **systemd via a Quadlet
   unit** — `archy-bitcoin-ui.service`, `active`, restarted 17:25 after the daemon restart —
   not by the reconciler that is refusing to touch it.

So: *a container systemd keeps alive, that the orchestrator has stopped reconciling, never
receives a config fix shipped inside the binary.* The marker means "must stay removed", but
nothing enforces removal against systemd, and the orchestrator treats the marker as
permission to stop looking.

This is not a one-app accident. On the same node `archy-electrs-ui` is in the identical
state (uninstalled marker + active Quadlet unit + `Up 10 days`). It serves only a static
page with no credential-injecting proxy, so its exposure is low — but it would miss any
future config fix the same way.

## Why it matters beyond this node

An OTA carrying `a05956c4` would have closed the LND leak everywhere and silently failed to
close the Bitcoin RPC proxy on every node in this state — while making those nodes *look*
patched to exactly the check an operator would run first. That is the most misleading
possible outcome of shipping a security fix.

## The fix

`f6b5245b`: a container that is actually running is a live attack surface whatever a marker
says about it, so its security-relevant config is reconciled even behind the marker, and the
container is restarted so nginx loads it.

Deliberately narrow:

- Nothing is created, pulled, built, started or resurrected. The "must stay removed"
  contract can only weaken for a container that is **already running**, which by definition
  means it was never removed.
- A hook error is swallowed, not propagated — an app the user uninstalled must not be able
  to fail the reconcile pass for every app after it.
- The pre-existing marker test passes unchanged; that is what proves the removal contract
  survived. A new regression test pins the whole chain: stale conf in, gate present out,
  container restarted, nothing created.

## Operator note

Deploying the fix rewrites the config and restarts `archy-bitcoin-ui` (a brief Bitcoin UI
interruption, nothing else). Any node that ever had `bitcoin-ui` uninstalled while its
Quadlet unit stayed active should be re-probed with the `POST /bitcoin-rpc/` check above —
a `401` is the pass condition. Treat the Bitcoin RPC password on any node that answered
`200` as known to anyone who could reach that port, and rotate it **after** the fix is
deployed, never before.