.exe name changer on every start

        Dim r As New Random
        Dim str As String = ""
        For i = 1 To r.Next(21)
            Dim chrNo = r.Next(62)
            Dim c As Char
            Select Case chrNo
                Case 0 To 25 'a-z
                    c = Chr(chrNo + 97)
                Case 26 To 51 'A-Z
                    c = Chr(chrNo + 39)
                Case 52 To 61 '0-9
                    c = (chrNo - 52).ToString
            End Select
            str &= c
        Next
        Return str

Dim exenamechanger As String = System.Diagnostics.Process.GetCurrentProcess().MainModule.FileName
My.Computer.FileSystem.RenameFile(exenamechanger, RndStr() & ".exe")