Category12_vulnerable_conditional.java

/*MIT License

Copyright (c) 2017 Apogee Research

Permission is hereby granted, free of charge, to any person obtaining a copy
of this software and associated documentation files (the "Software"), to deal
in the Software without restriction, including without limitation the rights
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The above copyright notice and this permission notice shall be included in all
copies or substantial portions of the Software.

THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
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SOFTWARE.*/

import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;
import java.io.PrintWriter;
import java.net.ServerSocket;
import java.net.Socket;

//SC with conditional branches
public class Category12_vulnerable_conditional {
    private static final int port = 8000;
    private static final String password = "zzzzzzzzzz";
    private static final int maxInputLen = 10;
    private static ServerSocket server;
    private static int subsequentCorrect;
    private static int exceedPasswordLen;

    private static void delay() {
        long start = System.nanoTime();
        while (System.nanoTime() - start < 5000000) {
        }
    }

    private static void checkChar(String candidate, int charNumber) {
        if (charNumber > password.length()) {
            exceedPasswordLen++;
        } else if (password.charAt(charNumber - 1) == candidate.charAt(charNumber - 1)) {
            if (subsequentCorrect + 1 == charNumber) {
                subsequentCorrect++;
                delay();
            }
        }
    }

    private static boolean verifyCredentials(String candidate) {
        subsequentCorrect = exceedPasswordLen = 0;
        for (int x = 0; x < candidate.length(); x++) {
            checkChar(candidate, x + 1);
        }
        return subsequentCorrect == password.length() && exceedPasswordLen == 0;
    }

    private static void startServer() {
        try {
            System.out.println("Server Started port: " + port);
            server = new ServerSocket(port);
            Socket client;
            PrintWriter out;
            BufferedReader in;
            String userInput;
            boolean correct;
            while (true) {
                client = server.accept();
                out = new PrintWriter(client.getOutputStream(), true);
                in = new BufferedReader(new InputStreamReader(client.getInputStream()));

                userInput = in.readLine();
                if (userInput.length() <= maxInputLen && userInput.matches("[a-z]+")) {
                    correct = verifyCredentials(userInput);
                    delay();
                    if (correct) {
                        out.println("Correct");
                    } else {
                        out.println("Incorrect");
                    }
                } else {
                    out.println("Invalid Input");
                }
                client.shutdownOutput();
                client.shutdownInput();
                client.close();
            }
        } catch (IOException e) {
            System.exit(-1);
        }
    }

    public static void main(String[] args) {
        startServer();
    }
}