Web Browser Filter

I would like to have a list of websites (each on a different line) that the web browser will check when navigated and if it is the current url then it will navigate back. Below is some code that I have currently have created and fails because it doesn't check each line of text and below that is some code that also check text with current text.

Using sr As New StreamReader("website_lists.txt")
        Dim lined As String
        lined = sr.ReadToEnd()
        Dim scanbox As New TextBox
        scanbox.Multiline = True
        Dim buff As StringBuilder = New StringBuilder
        For Each line In lined
            If TextBox1.Text.Contains(scanbox.Text) Then
                webview.GoBack()
                MsgBox("Infected website! For your own sake stay away!")
            End If
        Next
    End Using
End Sub

Some code that kinda does the same thing:

Dim md5 As MD5CryptoServiceProvider = New MD5CryptoServiceProvider
            Dim f As FileStream = New FileStream(ListBox1.SelectedItem, FileMode.Open, FileAccess.Read, FileShare.Read, 8192)
            f = New FileStream(ListBox1.SelectedItem, FileMode.Open, FileAccess.Read, FileShare.Read, 8192)
            md5.ComputeHash(f)
            Dim hash As Byte() = md5.Hash
            Dim buff As StringBuilder = New StringBuilder
            Dim hashByte As Byte
            For Each hashByte In hash
                buff.Append(String.Format("{0:X2}", hashByte))
            Next

            If scanbox.Text.Contains(buff.ToString) Then 

Have any suggestions or help? Thanks in advance.