PHP密码验证正在被绕过

Question

I want users to enter one of 4 passwords to get access to my site. The landing page is index.html and the redirect page should be home.html

I used the following code and I am using an if statement to hash the entered password and compare it with the 4 acceptable hases. If they match then I want the page to redirect. Otherwise I want to display a JS alert.

My issue is that even if the wrong password is entered, it still redirects with no alert.

//Take the values from the html form and assign them to variables
$ID = $_POST['name'];
$userpassword = $_POST['password'];

//Check to see if the password matches the hashes
if (md5($userpassword) === '5b5c45f1b9e444d9e441211cfb325270' 
    or '17434cf0d4ba816cd776ff8b0ec532f1' 
    or '7a94fda2a6e81a1693533e6dc8501b37' 
    or '2d8b2ba14eeb0ac1fe474d468b720771') 
{
//Add the visitor name to our list
  mysqli_query($connect, "INSERT INTO `visitor list` (`Visitor Name`) VALUES ('$ID')") or die("Error in INSERT: ".mysqli_error($connect));

  echo "You have entered the correct password, congrats.";
// Redirect them to rest of site
   header("Location: http://localhost:82/home.html");
      die();

}

else {
  echo "<script type='text/javascript'>alert('Wrong Password');</script>";
}

Answer 1

The code is only doing the comparison in for the first md5 hash but you have 4 conditions you want to satisfy so you would replace your if condition with this:

$hashedPassword = md5($userpassword);
if (   $hashedPassword == '5b5c45f1b9e444d9e441211cfb325270' 
    or $hashedPassword == '17434cf0d4ba816cd776ff8b0ec532f1' 
    or $hashedPassword == '7a94fda2a6e81a1693533e6dc8501b37' 
    or $hashedPassword == '2d8b2ba14eeb0ac1fe474d468b720771') 

The reason why it wasn't working is because the way PHP interpreted code was like this:

if (false/true or true or true or true) 

The md5 strings were seen as 'true' values. A string is only false if it is empty or it is equal "0" (but that's kind of a separate topic you can read about here .. so it is necessary to repeat the comparison.

An alternative way to do it would be to do this:

if (in_array(md5($userpassword), ['5b5c45f1b9e444d9e441211cfb325270', '17434cf0d4ba816cd776ff8b0ec532f1', '7a94fda2a6e81a1693533e6dc8501b37', '2d8b2ba14eeb0ac1fe474d468b720771'])

Basically it is checking if md5($userpassword) is defined in the array that is passed in the second argument.

More info on in_array:

in_array — Checks if a value exists in an array

Usage bool in_array ( mixed $needle , array $haystack [, bool $strict = FALSE ] )

Link http://php.net/in_array