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fix(security): harden backup code login path (hashing, rate limit, CSRF) #126

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fix(security): harden backup code login path (hashing, rate limit, CSRF) #126

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11 changes: 11 additions & 0 deletions lib/controllers.js
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Original file line number Diff line number Diff line change
Expand Up @@ -199,15 +199,26 @@ Controllers.generateBackupCodes = async (req, res) => {
};

Controllers.processBackup = async (req, res, next) => {
const count = await db.incrObjectField('locks', `backup:${req.uid}`);
if (count > 1) {
req.flash('error', '[[error:api.429]]');
await wait(10000); // 10s for spamming
return res.redirect(`${nconf.get('relative_path')}/login/2fa/backup`);
}

try {
const success = await parent.useBackupCode(req.body.code, req.user.uid);
if (!success) {
req.flash('error', '[[2factor:backup.failure]]');
await wait(2000);
await db.deleteObjectField('locks', `backup:${req.uid}`);
return res.redirect(`${nconf.get('relative_path')}/login/2fa/backup`);
}
// Success!
await db.deleteObjectField('locks', `backup:${req.uid}`);
next();
} catch (err) {
await db.deleteObjectField('locks', `backup:${req.uid}`);
req.flash('error', err.message);
res.redirect(`${nconf.get('relative_path')}/login/2fa/backup`);
}
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34 changes: 25 additions & 9 deletions library.js
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Original file line number Diff line number Diff line change
Expand Up @@ -5,6 +5,7 @@ const passportTotp = require('passport-totp').Strategy;
const notp = require('notp');
const { Fido2Lib } = require('fido2-lib');
const base64url = require('base64url');
const crypto = require('crypto');

const db = nodebb.require('./src/database');
const nconf = nodebb.require('nconf');
Expand All @@ -14,7 +15,6 @@ const meta = nodebb.require('./src/meta');
const groups = nodebb.require('./src/groups');
const plugins = nodebb.require('./src/plugins');
const notifications = nodebb.require('./src/notifications');
const utils = nodebb.require('./src/utils');
const routeHelpers = nodebb.require('./src/routes/helpers');
const controllerHelpers = nodebb.require('./src/controllers/helpers');
const SocketPlugins = nodebb.require('./src/socket.io/plugins');
Expand Down Expand Up @@ -57,7 +57,7 @@ plugin.init = async (params) => {
// 2fa Login
hostHelpers.setupPageRoute(router, '/login/2fa', [hostMiddleware.ensureLoggedIn], controllers.renderChoices);
hostHelpers.setupPageRoute(router, '/login/2fa/totp', [hostMiddleware.ensureLoggedIn], controllers.renderTotpChallenge);
router.post('/login/2fa/totp', hostMiddleware.ensureLoggedIn, controllers.processTotpLogin, (req, res) => {
router.post('/login/2fa/totp', hostMiddleware.ensureLoggedIn, hostMiddleware.applyCSRF, controllers.processTotpLogin, (req, res) => {
req.session.tfa = true;
const now = Date.now();
req.session.meta.datetime = now;
Expand All @@ -72,7 +72,7 @@ plugin.init = async (params) => {

// 2fa backups codes
hostHelpers.setupPageRoute(router, '/login/2fa/backup', [hostMiddleware.ensureLoggedIn], controllers.renderBackup);
router.post('/login/2fa/backup', hostMiddleware.ensureLoggedIn, controllers.processBackup, (req, res) => {
router.post('/login/2fa/backup', hostMiddleware.ensureLoggedIn, hostMiddleware.applyCSRF, controllers.processBackup, (req, res) => {
req.session.tfa = true;
res.redirect(guard(nconf.get('relative_path') + (req.query.next || '/')));
});
Expand Down Expand Up @@ -329,22 +329,24 @@ plugin.hasKey = async (uid) => {
return hasTotp || hasAuthn;
};

function hashBackupCode(code) {
return crypto.createHash('sha256').update(code).digest('hex');
}

plugin.hasBackupCodes = async uid => db.exists(`2factor:uid:${uid}:backupCodes`);

plugin.countBackupCodes = async uid => db.setCount(`2factor:uid:${uid}:backupCodes`);

plugin.generateBackupCodes = async (uid) => {
const set = `2factor:uid:${uid}:backupCodes`;
const codes = [];
let code;

for (let x = 0; x < 5; x++) {
code = utils.generateUUID().replace('-', '').slice(0, 10);
codes.push(code);
codes.push(crypto.randomBytes(6).toString('hex'));
}

await db.delete(set); // Invalidate all old codes
await db.setAdd(set, codes); // Save new codes
await db.setAdd(set, codes.map(hashBackupCode)); // Save hashes only

const notification = await notifications.create({
bodyShort: '[[2factor:notification.backupCode.generated]]',
Expand All @@ -364,10 +366,24 @@ plugin.generateBackupCodes = async (uid) => {
plugin.useBackupCode = async (code, uid) => {
const set = `2factor:uid:${uid}:backupCodes`;

const valid = await db.isSetMember(set, code);
if (typeof code !== 'string') {
return false;
}
code = code.trim().toLowerCase().replace(/[\s-]/g, '');
if (!code) {
return false;
}

const hashed = hashBackupCode(code);
// Codes generated before hashing was introduced are stored in plain text
const [validHashed, validLegacy] = await Promise.all([
db.isSetMember(set, hashed),
db.isSetMember(set, code),
]);
const valid = validHashed || validLegacy;
if (valid) {
// Invalidate this backup code
await db.setRemove(set, code);
await db.setRemove(set, validHashed ? hashed : code);

const notification = await notifications.create({
bodyShort: '[[2factor:notification.backupCode.used]]',
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2 changes: 1 addition & 1 deletion static/templates/login-backup.tpl
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Original file line number Diff line number Diff line change
Expand Up @@ -17,7 +17,7 @@
<div class="form-group">
<input type="text" class="form-control form-control-large text-center" id="code" name="code" autocomplete="off" />
</div>
<input type="hidden" id="csrf" name="csrf" value="{config.csrf_token}" />
<input type="hidden" name="csrf_token" value="{config.csrf_token}" />
<button class="btn btn-block btn-primary text-center" type="submit">{{tx("2factor:login.verify")}}</button>

<hr />
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2 changes: 1 addition & 1 deletion static/templates/login-totp.tpl
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Original file line number Diff line number Diff line change
Expand Up @@ -20,7 +20,7 @@
<input type="text" inputmode="numeric" class="form-control form-control-large text-center" id="code" name="code" autocomplete="off" />
<button class="btn btn-block btn-primary text-center" type="submit">{{tx("2factor:login.verify")}}</button>
</div>
<input type="hidden" id="csrf" name="csrf" value="{config.csrf_token}" />
<input type="hidden" name="csrf_token" value="{config.csrf_token}" />
</form>

<hr />
Expand Down