John Davidson

Message:

I am practising in a VM to improve my knowledge on producing secure code methodology and am stuck on fixing this vulnerable code snippet:

<div class="col post-addresses>

{{ post.content|striptags(<>)|raw }}

</div>

I understand the raw disables the encoding. What does the striptags do and also how does using md2html help?

Would using md2html in this context below help?

<div class="col post-addresses>

{{ post.content|md2html}}

</div>

Thanks

---

My Answer:
To fix the XSS vulnerability in your PHP code, you can use htmlspecialchars() function to encode special characters in the input data. Here's an example of how you can modify your code snippet:

php
// Original vulnerable code
$user_input = $_GET['input'];
echo $user_input;
?>

// Fixed code using htmlspecialchars()
$user_input = $_GET['input'];
echo htmlspecialchars($user_input, ENT_QUOTES, 'UTF-8');
?>


In the fixed code snippet, the htmlspecialchars() function is used to encode special characters in the user input before displaying it on the page. This helps prevent XSS attacks by converting characters like <, >, ", ', and & into their HTML entity equivalents.

Additionally, you can also use strip_tags() function to remove any HTML tags from the user input if you do not want to allow any HTML content to be displayed.

php
// Fixed code using strip_tags() and htmlspecialchars()
$user_input = $_GET['input'];
$clean_input = strip_tags($user_input);
echo htmlspecialchars($clean_input, ENT_QUOTES, 'UTF-8');
?>


By combining strip_tags() and htmlspecialchars() functions, you can effectively prevent XSS attacks in your PHP code. Remember to always sanitize and validate user input to ensure the security of your application.