Express with Secure Handlebars
We enhance the ExpressHandlebars server-side view engine by automatically applying Context-aware XSS output filters to better secure your web applications.
- Immediate Benefits: Our approach outperforms the existing HTML escaping by applying precise filtering rules that are specific to different output contexts, and is thus secure against more attack vectors while eliminating double encodings altogether. Kindly refer to xss-filters for details.
- Least Adoption Effort: The manual effort required is as easy as batch replacing
express-handlebars
with express-secure-handlebars
(i.e., to update those require()
calls as well as the dependency in your package.json
). The nitty-gritties of filter choices and integrations are all automated!
Quick Start
Installation
$ npm install express-secure-handlebars --save
Usage
Simply replace express-handlebars
with the express-secure-handlebars
package in all require()
!
Basic Example
Based on the basic example of ExpressHandlebars, here we show an example app that can be secured only with our package.
views/profile.handlebars:
Given that there is a very typical handlebars template file written like so to incorporate user inputs.
The enhanced package can secure the web application by automatically applying context-sensitive output filters, which otherwise is still subject to XSS attacks if using the default escaping approach (e.g., when url is javascript:alert(1) or onclick=alert(1)).
<h1>Example App: {{title}}</h1>
...
<div>User-provided URL: <a href="{{url}}">{{url}}</a></div>
...
views/layouts/main.handlebars:
Same as the Handlebars original example, this file serves as the HTML page wrapper which can be reused for the different views of the app. {{{body}}} is used as a placeholder for where the main content should be rendered.
<!DOCTYPE html>
<html>
<head><meta charset="utf-8"><title>{{title}}</title></head>
<body>
{{{body}}}
</body>
</html>
app.js:
A super simple Express app that registers the Handlebars view engine.
var express = require('express'),
exphbs = require('express-secure-handlebars');
var app = express();
app.engine('handlebars', exphbs({defaultLayout: 'main'}));
app.set('view engine', 'handlebars');
app.use('/profile', function (req, res) {
res.render('profile', {
title: 'User Profile',
url: req.query.url
});
});
app.listen(3000);
Development
Apply your changes to files in src/, and then run the tests.
$ npm test
Build
License
This software is free to use under the Yahoo Inc. BSD license.
See the LICENSE file for license text and copyright information.