PHP Executing Programs

You are strongly advised to check corresponding YouTube video at the end of this article.

HTML forms and PHP can be dangerous if not properly secured. They can potentially allow attackers to access and manipulate sensitive information, install malware on the server, or perform other malicious activities.

For example, attackers can use SQL injection to inject malicious code into SQL queries that are used to interact with a database. They can also use cross-site scripting (XSS) attacks to inject malicious scripts into web pages, which can be used to steal user data, redirect users to malicious sites, or perform other harmful actions.

To prevent these attacks, it's important to use best practices for web development, such as validating user input, sanitizing data, using prepared statements or parameterized queries for database interactions, and using encryption for sensitive data. Additionally, keeping software up to date and implementing security measures like firewalls and access controls can help reduce the risk of attacks. 

<?php 

system("calc");
system("notepad");

?>

This code will execute the Windows "calc" and "notepad" programs using the system() function in PHP.

Running arbitrary system commands like this can be dangerous as it allows an attacker to execute commands on the server running the PHP script. They can use this to run malicious code, steal sensitive data or damage the system. 

<?php 

echo "<pre>";
system("ping google.com");
echo "</pre>";

?>

This PHP code is using the system() function to execute the ping command on the command line, with google.com as the argument. The output of the command is then printed to the screen using the echo statement, wrapped in the <pre> HTML tag to preserve its formatting.

While this code itself is not necessarily harmful, it demonstrates a potential security vulnerability. If an attacker were able to inject malicious input into the $_POST variables used in this code, they could potentially execute arbitrary commands on the server, which could lead to serious security breaches. 

<?php 

echo "<pre>";

system("cmd");
system("dir");

echo "</pre>";

?>

In the above code, the "cmd" command opens the Windows command prompt, and the "dir" command lists the files and directories in the current directory of the command prompt. This could be a security risk if the script is not properly secured and only authorized users are allowed to access it.