Implementing Security in PHP

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Mar 3, 2024

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Many popular Websites such as Yahoo, Facebook, and Wikipedia are built using PHP. Building a Web application as per client needs is of utmost importance. At the same time, a PHP developer should take into consideration measures for cyber security as well. This should be done at the coding level, failing which the application becomes vulnerable to malicious attacks by potential cyber hackers. This is risky not only to organizations/enterprises but also to users, as dangerous malware can easily be injected into user's systems too.

Security Issues in PHP

Security issues can be caused in an application due to vulnerabilities that can be exploited by hackers to satisfy their malicious goals. Security is a key issue that must be addressed well before a Web application is launched. Security issues can either be found in the platform itself or they can happen due to the carelessness of the developer while building the application. The PHP interpreter is itself software and thus, can be vulnerable. This means that if one version of PHP is vulnerable, then all the applications using that version of PHP become automatically vulnerable. Hence, they can become susceptible to cyber hackers.

However, this is rare in action as highly capable developers and open-source communities often put in efforts to avoid such a scenario. Nevertheless, if such an event does occur, it is promptly hotfixed (quickly fixed or updated). The most common cause of security breaches and attacks is bad coding habits followed by a developer. A good developer should take care of any vulnerabilities in his/her application by following good coding habits. The developer should have sufficient foresight into all vulnerabilities and loopholes that might make applications prone to any kind of cyber attack. Also, the developer should be aware of how a user can misuse a piece of code. All end-user data submitted should be considered untrusted and should be properly sanitized.

Security issues in a Web application can lead to two types of attacks.

Client-side Attacks:

• Targets the users directly by targeting its browser.
• Cross-Site Scripting and Cross-Site Request Forgery are examples of such attacks.
  
  

Server-side Attacks:

• Targets a Web server to try and execute malicious code into the server.
  
• SQL Injection and XML External Entities are examples of such attacks.
  
  

Types of Common Attacks

A Web application written in PHP is at risk against many types of attacks. The OWASP Top 10 is an awareness document published by Open Web Application SecurityProject (OWASP) that highlights the top 10 Web application security risks developers should be aware of.

Some of these vulnerabilities are described briefly here:

1. Injection:

• Injects code in a Web application's input in a way that it is executed by the server.
  
  
• This leads to remote code execution that can give the attacker complete control over the target server.
  
  

2. Broken Authentication:

• Caused by flawed authentication methods such as insecurely written login pages and weak session IDs.
  
  
• Allows an attacker to bypass the mechanism and log in successfully as another user.
  
  

3. Sensitive Data Exposure:

• Credentials, credit card information, and other valuable customer data are all examples of sensitive data concerning the Web application.
  
  
• Caused by careless coding habits.
  
  
• Potential hacker uses this leaked information to fulfill their malicious intent.
  
  

4. Security Misconfiguration:

• The most prevalent issue found on most of the Websites.
  
  
• The result of insecure default configurations or misconfiguration can open loopholes that can be used by an attacker to gain access.
  
  

5. Cross-Site Scripting:

• This form of attack in which untrusted user input is taken in by a Web application and sent back to the browser without proper sanitization or filtering.
  
  
• Can trick the browser into executing malicious JavaScript hidden in the user input.
  
  

Cross-Site Scripting(XSS):

XSS is a client-side injection attack. XSS attacks users of a trusted Web application. This happens when an attacker injects malicious code into the Web page that the victim uses. The actual attack occurs when the user executes the malicious code.XSS is only dangerous when the input vulnerable to XSS is present in the URL as a GET parameter. The attacker then gets the JavaScript to be executed on the victim's browser. Various other attacks such as session hijacking, phishing, and website impersonation are possible using XSS.

SQL Injection Attacks:

SQL Injection (SQLi) attack is a type of injection attack in which an attacker injects malicious SQL statements into a vulnerable Web application. This leads to backend database manipulation allowing the attacker to get access to sensitive data that is not originally intended to be displayed. In certain cases, it allows the attacker to get remote code execution on the Web server. This allows the attacker to add, delete, or modify entire tables in a database that can adversely affect a business. This vulnerability arises due to insecure coding practices in which user input is passed on to the SQL interpreter without proper sanitization. This makes SQLi one of the topmost Web application vulnerabilities and thus, gaining the number one position in OWASP Top 10.

Session Hijacking

Sessions are created in PHP to save the state of a Web application. This state allows a logged-in user to remain logged in. Sessions are saved in correspondence to a Session ID. If an attacker gets hold of the Session ID, then the attacker can set the same Session ID in his browser by editing the cookie and hijacking the user's session.

Uploading Files Securely

Uploading an insecure file poses a risk to Web applications. File upload vulnerabilities are one of the common vulnerabilities in a Web application. This allows an attacker to upload any arbitrary file with malicious code in it to be executed on the server. The result can be dangerous to the system. It can range anywhere from the breakdown of the entire system to forwarding the code from the back-end system, and so on. So, it becomes essential to understand the devastating effects of uploading insecure malicious files as well as understand methods to exploit them.

Using SSL Certificates:

SSL Certificates allow a Website to prove its identity and provide encryption. This is provided by Certificate Authorities. Web servers require a certificate and a private key to enable SSL. For XAMPP on Windows, the Apache server accepts a certificate with an extension .crt and a private key of the format .key. Free SSL certificate obtained from Let's Encrypt.