Code Injection: An Easy Guide In 5 Points

Ajay Ohri


Code injection is the embedding of code into software, which disturbs the functioning of the software. The code introduced to the software can disturb the database integrity, security, features, etc. This article will discuss various aspects of code injection attacks, including their meaning, working, examples, and code injection examples. 

  1. What is code injection?
  2. Code Injection Example
  3. How does code Injection work?
  4. Types Of Code Injection
  5. How To Prevent Code Injection?

1. What is code injection?

In simple terms, code injection is injecting malicious code into an application, which results in a malicious attack. There is command injection as well, but it is different from command injection. Code injection is limited to the functionality of a particular code. For instance, if PHP injections occur in an application, it will only affect the functions brought to that application by that particular language. 

2. Code Injection Example

Given below is the code injection example- 

<?PHP eval (“echo “/$_REQUEST[“user_name”].”;); ?>

In the above code, the PHP will evaluate everything that is passed to the parameter username. There should be a valid username for the query string. An example of this is-

Now in this code, the attacker can exploit the application by injecting a PHP code-;phpinfo();

Now, after this injection, the PHP injector will echo admin. After that, phpinfo() will be executed. The information will be provided to the attacker after the code successfully runs. Details and information such as PHP version, operating system, and configuration details will be given to the attacker. 

Code injection can only use the function only if the system() is disabled in the PHP interpreter settings. Then for the Linux-based server, the following URL is supplied.;system(‘ls-l’);

This will also echo the domain. The code, which is present after the semicolon, i.e., system(‘ls-l’), will be executed. In the above command, the system(‘ls-l’) will run the ls-l command.

3. How does code Injection work?

When an application lacks proper input validation, i.e., it does not sanitize the data stored, then that application is vulnerable to code injection. Before talking about working, let’s discuss what user input is. In simple terms, any data which is fed by the user in the application is called user input, which is to be then processed by the application. The developers design the application only to accept certain input types. The application on which the code is being injected expects specific types of input. In some cases, the developer might show negligence when it comes to ensuring the correct data fed to the application.  

Various applications are prone to code injection attacks. eval() code is used for the code injection. The attacker exploits the application by injecting the code as the user input. Once the attack is successful, the attackers get access to the system information and the database. 

4. Types Of Code Injection

There are various types of code injection, including SQL injection and cross-site scripting, including HTML code injection and javascript code injection.

  • SQL Injection: These are the most common types of code injection. These take place on websites and web-application. This is so because various websites and web-application run on SQL, and injecting SQL malicious code gives you access to the website’s database. 
  • Cross-Site Scripting (XSS) – With this injection type, the user can be redirected to any other website. When the application or the website is injected with this type of code, users will be redirected to any other malicious website. 
  • OS command injection- This type of code gets injected into the operating system through the web application. Some web applications execute system commands in the operating system. In this case, the code can get injected into the OS. 

These were some of the most common code injection that can be seen online. 

5. How To Prevent Code Injection?

There are various ways to prevent code injection. Given below are some tips to help with the prevention of code injection. 

  • Scan the application for various escape characters and various other special symbols. Make sure the application accepts only a limited set of values. 
  • Ensure that eval() code is avoided in the raw inputs that are given by users. They only use language-specific features. 
  • You should know that any data set can have an attack code injected, so you should treat all the data as untrusted. You should know where your data can be manipulated. Code injection is not limited to HTML code and query strings. These code injections can also take place in cookies and data files.
  • The next step to avoiding code injection is to lock down your interpreter. This is only possible if you have control of the server configuration in your hands. The functionality of the interpreter can be limited if you have the control. This can be done to limit the functionality to the minimum required for your application. This can be explained with the example- remove system() function if your application is not using this function. This can be done by specifying it in the disable_functions directive. 
  • Various static code checking tools can help you check your code. These tools will help you check your code for any unwanted code and help you validate and sanitize your code. 
  • There are dynamic web vulnerability scanners that can help you with scanning your application. These scanners will help you make sure that the applications you use are safe from various online attacks. 


The world of the internet is full of threats, and there are new types of threats that keep on hitting the internet. And from these threats and cyber-attacks, you need to stay away. When you are surfing online, there can be chances that you will be the next target of the cyber attack. One such attack is code injection, which affects your connection to the web application and exploits your results. Well, there are various methods as well to help you with avoiding this type of cyber attack. Code injection attack can include- java injections, PHP code injections, HTML code injection, and javascript injection.

These affect only the particular type of functionality, which is only provided by the particular code. This article discusses the various aspects of code injection. Reading this article will help you learn what code injection is and how it is implemented. This is explained with the example of the code injection. This article also explains the various methods to help prevent code injections, and how dangerous it can be for your system and data. 

So, have you made up your mind to make a career in Cyber Security? Visit our Master Certificate in Cyber Security (Red Team) for further help. It is the first program in offensive technologies in India and allows learners to practice in a real-time simulated ecosystem, that will give you an edge in this competitive world.

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