A07:2025 Authentication Failures

// VULNERABLE://   app.post('/login', async (req, res) => { if (await check(req.body)) ... });   // unlimited attempts// FIXED:class LoginGuard {  constructor({ maxFree = 5, baseMs = 1000, capMs = 15 * 60_000 } = {}) {    this.maxFree = maxFree; this.baseMs = baseMs; this.capMs = capMs; this.state = new Map();  }  check(key, now) {    const s = this.state.get(key);    return !s || now >= s.lockedUntil;  }  fail(key, now) {    const s = this.state.get(key) || { fails: 0, lockedUntil: 0 };    s.fails += 1;    if (s.fails > this.maxFree) s.lockedUntil = now + Math.min(this.capMs, this.baseMs * 2 ** (s.fails - this.maxFree - 1));    this.state.set(key, s);  }  success(key) { this.state.delete(key); }}const guard = new LoginGuard();let now = 1_000_000;for (let i = 0; i < 5; i++) { assert.equal(guard.check('acct:alice', now), true); guard.fail('acct:alice', now); }guard.fail('acct:alice', now);                                    // 6th fail => locked 1sguard.fail('acct:alice', now + 1000);                             // 7th => 2sguard.success('acct:alice');// Key on BOTH account and IP; also check HIBP range API: GET /range/{sha1[0..5]} -> compare suffixes locally.

const breached = new Set(['password', '123456', 'qwerty', 'letmein']);   // stand-in for HIBPfunction passwordOk(pw) {  return typeof pw === 'string' && pw.length >= 12 && pw.length <= 128 && !breached.has(pw.toLowerCase());}

// VULNERABLE://   req.session.user = user;                   // same session id before and after login => fixation//   cookie: 'sid=' + Date.now()                // predictable; no expiry; no flags// FIXED:class SessionStore {  constructor({ idleMs = 30 * 60_000, absoluteMs = 12 * 3_600_000 } = {}) {    this.idleMs = idleMs; this.absoluteMs = absoluteMs; this.sessions = new Map();  }  newId() { return crypto.randomBytes(32).toString('base64url'); }  create(data, now) {    const id = this.newId();    this.sessions.set(id, { ...data, createdAt: now, lastSeen: now });    return id;  }  get(id, now) {    const s = this.sessions.get(id);    if (!s) return null;    if (now - s.lastSeen > this.idleMs || now - s.createdAt > this.absoluteMs) { this.sessions.delete(id); return null; }    s.lastSeen = now;    return s;  }  login(oldId, user, now) {                    // rotate: destroy pre-auth session, mint a new id    const prev = this.sessions.get(oldId);    this.sessions.delete(oldId);    return this.create({ ...(prev ? { cart: prev.cart } : {}), userId: user.id }, now);  }  destroy(id) { this.sessions.delete(id); }}const store = new SessionStore();let t = 5_000_000;const anonId = store.create({ cart: ['sku1'] }, t);const authId = store.login(anonId, { id: 'u1' }, t);const longId = store.create({ userId: 'u2' }, t);for (let i = 1; i <= 13; i++) store.get(longId, t + i * 3_600_000 - 60_000);   // keeps touching it

const sessionCookie = Object.freeze({  name: '__Host-sid',          // __Host- prefix: Secure, no Domain, Path=/  httpOnly: true,              // JS cannot read it  secure: true,                // HTTPS only  sameSite: 'Lax',             // 'Strict' if no cross-site top-level nav needed; CSRF mitigation  path: '/',  maxAge: 30 * 60,             // seconds; match idle timeout});

// VULNERABLE: token = user.id + Date.now(); stored plaintext; never expires; reusable; emailed in a GET link w/o Referrer-Policy.// FIXED:const resetTokens = new Map();   // sha256(token) -> { userId, exp, used }function issueReset(userId, now, ttlMs = 15 * 60_000) {  const token = crypto.randomBytes(32).toString('base64url');  resetTokens.set(crypto.createHash('sha256').update(token).digest('hex'), { userId, exp: now + ttlMs, used: false });  return token;                 // only the user ever sees the raw token}function consumeReset(token, now) {  const h = crypto.createHash('sha256').update(String(token)).digest('hex');  for (const [k, rec] of resetTokens) {    if (k.length === h.length && crypto.timingSafeEqual(Buffer.from(k), Buffer.from(h))) {      if (rec.used || now > rec.exp) return null;      rec.used = true;      return rec.userId;    }  }  return null;}const rt = issueReset('u1', t);const rt2 = issueReset('u1', t);// Generic responses: "If that account exists, we sent an email." Same timing for both branches.