Why PHP is Secure: The Truth About Server-Side Language Security

By Bisma •  Updated: 06/29/22 •  8 min read

If you’re new to PHP, you might be wondering why it is so secure. In this article, we’ll discuss SQL Injection, XSS, Active code, and Open_basedir. If you’re not sure how these vulnerabilities are exploited, check out these tips to keep your site secure. The next time you’re working on a PHP project, remember to implement the most secure security measures possible.

  1. SQL Injection

One of the most critical aspects of securing your website against SQL injection is ensuring that all user input is validated. This includes using radio buttons and drop-down menus and proper error handling in your web server and code. An attacker can use the technical details of an error message to alter a query to suit their purposes. In addition, input filtering may prevent simple SQL injection attacks but will not solve the underlying vulnerability.

The way to prevent SQL Injection is to ensure that all errors are logged to an error log that is not accessible by the web server. For example, you can use PHP to log all errors in an error log, or use another file. In either case, you must be careful to ensure that the file is not accessible by the attacker. You can also run a test against your website to confirm that it is secure against this security flaw.

  1. XSS

PHP is secure against XSS attacks in two ways: by validating input data and escaping malicious URLs. PHP’s htmlentities function encodes HTML entities and is called by developers to escape user-supplied HTML input. It’s straightforward and highly efficient, so even beginners can use it to protect themselves against XSS. JavaScript, the language behind many modern web applications, uses the Document Object Model to create dynamic content. Dynamic content can be vulnerable to XSS attacks because malicious links and the code can be embedded in the HTML.

The most common threat vector for XSS attacks is the user-input interface. Organizations must educate users about the impact of XSS attacks and disclose any malicious characters in the user input. Developers can also protect themselves from XSS attacks by ensuring that user input is clean and uses secure transfer protocols like HTTPS or HTTP. They should set up filters that ensure numeric inputs are integers. Whitelisting is another suitable method of protecting applications from XSS attacks.

  1. Open_basedir function

The open_basedir function in PHP is secure because it disallows PHP scripts to access files outside of their configured base directories. These restrictions are set to prevent remote attackers from exploiting vulnerabilities in the file system. PHP functions will check if an object is allowed to open a particular file before making the actual open call. If the object is, then it is likely to point to a prohibited file during the specified time period.

PHP’s symlink function uses a filename matching the open_basedir restriction. If the file name matches a file name in the open_basedir restriction, the PHP script will only be able to access it. This means that you can use symbolic links to work around this restriction. However, this can’t be used for directories outside the specified directory tree.

  1. Active code

The PHP language has some security features built-in to protect the application from being hacked. PHP pages can include files in the document root that are commonly used for PHP calls. The libraries in these files can be attacked in several ways, such as by directly calling the program code contained in the library file. The attacker can then leverage this code to cause unwanted effects on the application. For this reason, it is vital to use only libraries with built-in security features.

The ZipArchive class in PHP has a number of security features. This class can be activated with the –with-zip flag. This allows the application to avoid exploits that can expose the ZIP archive’s contents. If it is not protected, it can be hacked by introducing heisenbugs. It is also essential to use secure encoding for JSON data. By using secure encoding, PHP applications are more secure.

  1. eval()

PHP eval() is secure because it does not decode the user input. It may contain malformed code, which can result in remote code execution. To ensure your code is secure, it is vital to ensure that your script validates the user input. If it does not, you may be exposing your site to malicious attacks. To prevent such incidents, always review your source code to ensure that the eval() function is used only for legitimate purposes.

PHP eval() is a language construct that allows execution of arbitrary PHP code. The use of eval() is discouraged in most applications, and you should avoid it whenever possible. You should avoid passing user data into eval() without proper validation. To make your code secure, use call_user_func() instead. It allows you to capture the eval() output in a string and hide any fatal errors.

  1. eval() hides an attacker’s tools

The use of eval() to generate code is a serious security issue as this function is hard to secure. Many programming languages are designed to make it easy for a human to write instructions, and as such, they are filled with quirks and special behaviors. JavaScript automatically adds a ‘;’ to some statements. In addition, eval() can be dangerous because it generates code from hostile data, such as the ‘;’ character from JavaScript.

PHP provides a wealth of options for encoding and encryption. PHP has advanced string obfuscation patterns and superglobals. It also allows users to include code via filters or streams. Many web applications are vulnerable to local file inclusions, which are very difficult to detect without the use of forensics. Using eval() properly can help protect your website from attacks, but it’s not recommended.

  1. Cross-site scripting

One of the most common security attacks that web developers deal with is the threat of cross-site scripting, also known as XSS. This attack is possible due to incorrectly validating user data in a web form. The attacker can use this error to inject malicious code, which may then execute malicious action inside the user’s browser. PHP includes a number of security measures to protect against this attack, including using htmlspecialchars() and strip_tags().

XSS attacks are facilitated by web applications that do not sanitize input. XSS vulnerabilities can allow attackers to inject malicious JavaScript in a web page and hijack the user’s session or steal sensitive information. Depending on how the attacker is able to exploit the XSS vulnerability, they could perform any number of malicious actions, including uploading malware, phishing attacks, and orchestrating full-blown attacks.

To prevent XSS attacks, developers should adhere to consistent, secure coding practices. One such tool is the Veracode vulnerability decoder, which provides guidelines on how to prevent XSS-based attacks. Additionally, developers should ensure that any input is properly escaped. Proper input escape can prevent attackers from misusing the application. Cross-site scripting prevention should be part of your development and production processes to detect potential vulnerabilities and prevent attacks.

Bottom line: Security best practices

While security is important, it is not always obvious. In fact, the payoffs of good security are largely obscure. A security checklist is a useful tool to develop PHP applications that improve code security.

Resources links:

https://www.cloudways.com/blog/php-security/
https://blog.securityinnovation.com/php-security-the-good-the-bad-and-the-ugly

Bisma

Bisma is a cybersecurity geek who loves to write about secure VPN connections. She works in Astrill VPN Astrill VPN and provides her point of view on several security-related issues.