Skip to content

Instantly share code, notes, and snippets.

@ziadoz

ziadoz/index.php

Last active June 2, 2023 23:08
Show Gist options
  • Save ziadoz/3454607 to your computer and use it in GitHub Desktop.
Save ziadoz/3454607 to your computer and use it in GitHub Desktop.
Download ZIP
Simple PHP / jQuery CSRF Protection
Raw
index.php
<?php
// See: http://blog.ircmaxell.com/2013/02/preventing-csrf-attacks.html
// Start a session (which should use cookies over HTTP only).
session_start();
// Create a new CSRF token.
if (! isset($_SESSION['csrf_token'])) {
$_SESSION['csrf_token'] = base64_encode(openssl_random_pseudo_bytes(32));
}
// Check a POST is valid.
if (isset($_POST['csrf_token']) && $_POST['csrf_token'] === $_SESSION['csrf_token']) {
// POST data is valid.
}
?>
<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="utf-8" />
<title>PHP CSRF Protection</title>
<script>
window.csrf = { csrf_token: '<?php echo $_SESSION['csrf_token']; ?>' };
$.ajaxSetup({
data: window.csrf
});
$(document).ready(function() {
// CSRF token is now automatically merged in AJAX request data.
$.post('/awesome/ajax/url', { foo: 'bar' }, function(data) {
console.log(data);
});
});
</script>
</head>
<body>
<form action="index.php" method="post" accept-charset="utf-8">
<input type="text" name="foo" />
<input type="hidden" name="csrf_token" value="<?php echo $_SESSION['csrf_token']; ?>" />
<input type="submit" value="Submit" />
</form>
</body>
</html>
@omidgfx
Copy link

omidgfx commented Sep 25, 2019

Maybe I am wrong, but:

* If I can steal your cookie => I can steal your session (Session will set a session cookie, that's how you are connected to a server session, remember?)

* If I can steal your session, I can steal your "hidden" token.

Instead

* Regenerate session_id on a regular basis.

* Delete obsolete sessions so that they cannot be revived.

I would not suggest relying on this code to anyone.

Some starting point

http://eddmann.com/posts/securing-sessions-in-php/

http://resources.infosecinstitute.com/fixing-csrf-vulnerability-in-php-application/

I think there's a way:

function sess_start() {
    @session_set_cookie_params(3600 /* one hour */, '/', null, false, true);
    @session_start();
}

function sess_create() {
    @session_unset();
    @session_destroy();
    sess_start();
    $_SESSION['client_ip'] = $_SERVER['REMOTE_ADDR'];
}

function sess_init() {
    sess_start();
    if (!isset($_SESSION['client_ip']) || $_SESSION['client_ip'] != $_SERVER['REMOTE_ADDR'])
        sess_create();
}

// Start from here
sess_init();

// do the rest, now you can't steal this cookie / session

@ziadoz
Copy link
Author

ziadoz commented Sep 30, 2019 •
edited
Loading

You shouldn't be using this code (or any code you've just plucked off Gists for that matter). It's seven years old and has many issues (e.g. no session id regeneration, no timing safe comparison, doesn't clear tokens when used).

I recommend taking a look at this guide a starting point instead: https://paragonie.com/blog/2017/12/2018-guide-building-secure-php-software

Sign up for free to join this conversation on GitHub. Already have an account? Sign in to comment