F-10/F-11 + Verwaltungsskript

- F-10 Open Redirect: is_safe_url()-Pruefung des next-Parameters beim Login; login_required gibt next weiter, Login-Formular traegt es als Hidden-Feld. Externe/protokoll-relative Ziele werden ignoriert -> Dashboard. - F-11 Info-Leak: eigene Fehlerseiten (400/403/404/405/500) ohne Framework- Hinweis oder Stacktrace (templates/error.html). - manage.sh: 'unlock' (Brute-Force-Sperren aufheben) und 'reset-password' (Admin-Passwort setzen/zufaellig erzeugen) via docker-compose run. Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
2026-06-06 15:49:04 +02:00
parent a5787a5393
commit 91993eb487
4 changed files with 180 additions and 3 deletions
@@ -7,7 +7,7 @@ import socket
 import sqlite3
 from datetime import datetime, timedelta
 from functools import wraps
-from urllib.parse import urlparse
+from urllib.parse import urljoin, urlparse

 from flask import (Flask, Response, abort, flash, redirect, render_template,
                   request, session, url_for)
@@ -82,6 +82,49 @@ def _inject_csrf():
    return {'csrf_token': lambda: session.get('_csrf_token', '')}


+# ---------------------------------------------------------------------------
+# Eigene Fehlerseiten (verraten kein Framework, kein Stacktrace)
+# ---------------------------------------------------------------------------
+
+ERROR_MESSAGES = {
+    400: 'Ungültige Anfrage.',
+    403: 'Zugriff verweigert.',
+    404: 'Seite nicht gefunden.',
+    405: 'Methode nicht erlaubt.',
+    500: 'Interner Serverfehler.',
+}
+
+
+def _render_error(code):
+    return render_template('error.html', code=code,
+                           message=ERROR_MESSAGES.get(code, 'Fehler')), code
+
+
+@app.errorhandler(400)
+def _err_400(e):
+    return _render_error(400)
+
+
+@app.errorhandler(403)
+def _err_403(e):
+    return _render_error(403)
+
+
+@app.errorhandler(404)
+def _err_404(e):
+    return _render_error(404)
+
+
+@app.errorhandler(405)
+def _err_405(e):
+    return _render_error(405)
+
+
+@app.errorhandler(500)
+def _err_500(e):
+    return _render_error(500)
+
+
 # ---------------------------------------------------------------------------
 # Helpers
 # ---------------------------------------------------------------------------
@@ -90,11 +133,20 @@ def login_required(f):
    @wraps(f)
    def wrapped(*args, **kwargs):
        if 'admin_id' not in session:
-            return redirect(url_for('login'))
+            return redirect(url_for('login', next=request.path))
        return f(*args, **kwargs)
    return wrapped


+def is_safe_url(target):
+    """True nur für relative Ziele auf derselben Origin (Open-Redirect-Schutz)."""
+    if not target:
+        return False
+    ref = urlparse(request.host_url)
+    test = urlparse(urljoin(request.host_url, target))
+    return test.scheme in ('http', 'https') and ref.netloc == test.netloc
+
+
 # --- Brute-Force-Schutz (DB-gestützt, pro Scope + Client-IP) ---------------
 # Der Schlüssel ist "<scope>:<ip>", damit Admin-Login ('login') und
 # DynDNS-Update ('dyndns') getrennt gezählt werden.
@@ -194,7 +246,8 @@ def login():
            session.clear()
            session['admin_id'] = admin['id']
            session['admin_username'] = admin['username']
-            return redirect(url_for('dashboard'))
+            nxt = request.form.get('next') or request.args.get('next')
+            return redirect(nxt if is_safe_url(nxt) else url_for('dashboard'))

        _record_login_fail('login', ip)
        flash('Benutzername oder Passwort falsch.', 'danger')
@@ -0,0 +1,21 @@
+<!DOCTYPE html>
+<html lang="de">
+<head>
+  <meta charset="UTF-8">
+  <meta name="viewport" content="width=device-width, initial-scale=1.0">
+  <title>{{ code }} — DynDNS Manager</title>
+  <link rel="stylesheet" href="https://cdn.jsdelivr.net/npm/bootstrap@5.3.2/dist/css/bootstrap.min.css">
+  <link rel="stylesheet" href="{{ url_for('static', filename='css/login.css') }}">
+</head>
+<body class="justify-content-center">
+<div class="login-card text-center">
+  <div class="card shadow">
+    <div class="card-body p-5">
+      <div class="display-4 fw-bold text-primary mb-2">{{ code }}</div>
+      <p class="text-muted mb-4">{{ message }}</p>
+      <a href="{{ url_for('dashboard') }}" class="btn btn-primary">Zur Startseite</a>
+    </div>
+  </div>
+</div>
+</body>
+</html>
@@ -23,6 +23,7 @@
      {% endwith %}
      <form method="post">
        <input type="hidden" name="csrf_token" value="{{ csrf_token() }}">
+        <input type="hidden" name="next" value="{{ request.args.get('next', '') }}">
        <div class="mb-3">
          <label class="form-label fw-semibold">Benutzername</label>
          <input name="username" type="text" class="form-control" autofocus required>