What is Code Injection? (How it Works, How to Prevent)

Remote Code Execution (RCE), often known as Code Injection, is a sort of attack in which an attacker can inject and execute malicious code into an application. This foreign code has the ability to compromise data security and integrity. It can often get through authentication controls, and these attacks are generally linked to apps that rely on user input to run.

Code Injection attacks take advantage of a sloppy data management. These attacks are typically made feasible by a lack of sufficient input/output data validation, such as −

  • Data format

  • Quantity of anticipated data

  • Allowable characters

SQL injection, Script injection, Shell injection, and Dynamic evaluation are the four primary forms of code injections. All of them function on the same idea that a code is injected into and executed by programs.

What is Command Injection?

In Command Injection, an attacker's options are restricted solely by the capabilities of the injected language. An attacker is only restricted by PHP's capabilities if they are able to inject PHP code into an application and have it executed. Using existing code to execute commands, generally inside the context of a shell, is known as command injection.

How Does Code Injection Work?

When an application doesn't have adequate input validation or doesn't sanitize the data it stores, it's exposed to code injection.

Let's talk about what "user input" is before we get into functioning. In simple terms, user input refers to any data that a user enters into an application and that the program subsequently processes.

The program is only designed to accept particular input types, according to its creators. The application into which the code is being injected anticipates certain sorts of data. In rare circumstances, the developer may be careless in ensuring that the right data is provided to the program.

Code injection attacks may affect a variety of apps. Code injection is done via the eval() function. By inserting code as user input, the attacker abuses the program. The attackers gain access to the system information and database after the attack is successful.

Hackers initially look for attack surfaces in the application that can receive untrusted data and utilize it to execute computer code. Direct input, such as file uploads and form fields, as well as additional data sources like cookies and query string parameters, are the examples.

A straight concatenation of character strings, the PHP eval() function, or its counterpart in another language is usually used to introduce code. An attacker can get access to the application's server-side interpreter if the vulnerability is successful. The attackers can utilize system calls to execute instructions on the server and get access to further information.

How to Prevent Code Injection Attacks?

Developers can take the following precautions to prevent Code Injection Attacks −

Use Whitelisting for Input Validation

Whitelisting is easier to set up and allows security teams more control over what data or types of input the application may handle, lowering the chance of malicious code being executed by an attacker.

Use Contextual Output Encoding

Use contextual output encoding to transform harmful input into safer representations, where user data can be presented but not executed as code.

Use a Static Type System

To ensure language separation, use a static type system. With static type systems, teams may create declarative control checks without the added runtime cost.

Avoid Using Unsafe Functions in the Source Code

It's vital to avoid utilizing any vulnerable code evaluation structures when developing source code. Instead, developers should employ safe, language-specific functionality to manage user-supplied inputs.

Use the HttpOnly Flag on Cookies

Use the HttpOnly flag on cookies to prevent client-side script interaction. The HttpOnly flag on every cookie that the server creates indicates that the cookie should not be accessible from the client-side. As a consequence, even if there are issues with HTML injection, the cookies cannot be shared with third parties.