Secure Coding: An Introduction to Principles and Practices

Dr Magda CHELLY, CISSP, PhD
Magda On Cyber
Published in
7 min readJul 11, 2022

In the world of software, coding is everything. The code developers write determines how well a program functions and how secure it is from potential attacks.

In this blog post, we will be discussing the basics of secure coding. This is an essential topic for all developers, regardless of experience level. We will cover the principles of secure coding and some best practices that should be followed when writing code. Following these guidelines can help protect your applications from potential security threats.

What is a vulnerability in code?

A vulnerability is a weakness that an attacker can exploit to gain access to sensitive data or perform unauthorized actions. There are many different types of vulnerabilities, but some of the most common include buffer overflows, SQL injection, and cross-site scripting (XSS).

Vulnerabilities can exist in any type of code, but they are often found in programs that are written in interpreted languages such as PHP, Perl, and Python. This is because these languages do not perform any type of compile-time checking, which means that errors can go unnoticed until the program is actually executed.

Another reason why vulnerabilities are often found in web applications is because they typically handle a large amount of user input . This gives an attacker a greater chance of finding a way to exploit the system.

What are some common security vulnerabilities?

Some common security vulnerabilities include SQL injection, cross-site scripting (XSS), and buffer overflows. These are just a few of the many types of vulnerabilities that can be present in code.

What is a vulnerability life cycle?

The vulnerability life cycle is the process a security flaw goes through, from discovery to patching. It typically includes the following stages:

- Discovery: A security researcher finds a new vulnerability and discloses it to the affected vendor.

- Disclosure: The vendor acknowledged the issue and released a public advisory with information about the flaw.

- Exploit: Attackers develop code that exploits the vulnerability and begins attacking systems.

- Patch: The vendor releases a patch or update that fixes the issue.

How does a cyber attack happen?

A cyber attack is a type of security breach that is carried out by using computers and the internet to target and exploit vulnerabilities. There are many different types of cyber attacks, but some of the most common include denial-of-service (DoS) attacks, malware infections, and phishing scams.

Cyber attacks can have a variety of purposes, such as stealing data, disrupting services, or taking over systems. Sometimes, an attacker may launch a cyber attack simply to cause damage or chaos.

What are some common cyber-attacks?

There are a number of common cyber attacks that developers should be aware of. These include cross-site scripting (XSS), SQL injection, and session hijacking.

Cross-site scripting (XSS) is a type of attack where malicious code is injected into a web page. This code is then executed by the users who visit the page. XSS can be used to steal information or to perform other malicious actions.

SQL injection is a type of attack where malicious input is used to execute SQL commands on a database server. This can be used to modify or delete data, or to access sensitive information.

Session hijacking is a type of attack in which a user’s session is hijacked to gain access to their account. This can be done by stealing the user’s cookies or by using a man-in-the-middle attack.

These are just some of the common attacks, leading to security risks that developers should be aware of. There are many others, and new attacks are constantly being discovered.

Developers need to be aware of these risks in order to prevent them from happening.

What are the principles of secure coding?

The principles of secure coding are a set of guidelines that should be followed when writing code. These guidelines help reduce the chances of vulnerabilities in your applications.

Photo by Chris Ried on Unsplash

Why do we have bad code?

Bad code is code that contains vulnerabilities. This can happen for a variety of reasons, such as careless coding, not following secure coding principles, or not having enough experience. Software developers might not have the required training about secure coding practices, so they might not be aware of the potential risks.

How to build a secure architecture?

There is no single silver bullet for building a secure architecture, but there are some general principles that can be followed. These include using security by design, defense in-depth, and least privilege.

Security by design is the practice of building security into the architecture from the start. This means that all components and systems are designed with security in mind and built into the development process.

Defense in-depth is the practice of using multiple layers of security to protect systems. This approach makes it more difficult for attackers to find and exploit vulnerabilities.

Least privilege is the practice of only granting users the permissions they need to perform their job. This helps to limit the damage that can be done by a malicious user, as they will only be able to access the resources that they have permission for.

Regarding security, following these principles can help make your applications more robust and less likely to be exploited.

What are the security challenges with third-party code or libraries?

Using third-party code or libraries can introduce security risks into your applications. This is because you are relying on the security of these external components. If these components are not secure, then your application will also be vulnerable. It is important to vet these third-party components carefully before using them.

How does good design matter?

Good design is important for security, as it can help to reduce the chances of vulnerabilities being present in your code. This is because good design makes code more understandable and easier to review. It also makes it easier to spot potential security issues.

What is the role of coding standards?

Coding standards help to ensure that code is written in a consistent way. This makes it easier to read and understand, and it also makes it easier to spot potential security issues. Coding standards can also help to prevent vulnerabilities from being introduced in the first place.

Some coding standards include the Secure Coding Guidelines from the CERT Coordination Center, the Microsoft Security Development Lifeline, and the OWASP Top Ten.

Following coding standards, is vital for security, as it can help to reduce the chances of vulnerabilities being present in your code.

What are some common secure coding practices?

There are a number of secure coding practices that developers should follow. These include input validation, output encoding, error handling, and using secure APIs.

Input validation is the process of ensuring that data received by an application is valid. This helps to prevent malicious input from being processed by the application.

Output encoding is the process of converting data into a format that is safe to display. This helps to prevent cross-site scripting (XSS) attacks.

Error handling is the process of gracefully dealing with errors in an application. This includes hiding sensitive information from users and logging errors for debugging purposes.

Using secure APIs is the practice of using interfaces that are designed to be secure. This includes using encryption when possible and verifying permissions before allowing access to data.

Secure coding practices help to make applications more secure by making it harder for attackers to exploit vulnerabilities.

Photo by Collins Lesulie on Unsplash

Automation and testing

What is the difference between static and dynamic code analysis?

Static code analysis is a type of code review that is done without actually executing the code. This means that it can be done before the software is even deployed. Static code analysis can find vulnerabilities that traditional testing methods would otherwise miss.

Dynamic code analysis is a type of security testing that is done by executing the code and observing its behavior. This type of testing is often used to find vulnerabilities that are difficult to detect using static methods.

Penetration testing and vulnerability assessment?

Penetration testing is a type of security testing used to find and exploit vulnerabilities in a system. This type of testing is often done by ethical or white hat hackers.

Vulnerability assessment is a process of identifying, classifying, and prioritizing vulnerabilities in a system. This helps organizations to understand the risks associated with these vulnerabilities and to take steps to mitigate them.

Both penetration testing and vulnerability assessment are important for security. They help to find and fix vulnerabilities before attackers can exploit them.

In conclusion, following secure coding principles and practices can help to make your applications more robust and less likely to be exploited. Security starts with good design and coding standards, followed by secure coding practices such as input validation, output encoding, and error handling. Secure coding is important for security, as it can help reduce the chances of vulnerabilities being present in your code. There are a number of secure coding practices that developers should follow, which include input validation, output encoding, error handling, and using secure APIs.Automation and testing can also help to find and fix vulnerabilities before they are exploited.

I hope this has been a helpful introduction to secure coding principles and practices. If you have any questions, please feel free to leave a comment below.

Thanks for reading!

By Magda Chelly

Chief Security Officer | TEDx Speaker | Author & Keynote Speaker | IFSEC Global Top 20 Cybersecurity Influencer | Entrepreneur | PhD, S-CISO, CISSP, Cert SCI (General Insurance)

Find out on magda-on-cyber.com

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Dr Magda CHELLY, CISSP, PhD
Magda On Cyber

Cyberfeminist | Entrepreneur | Former CISO | PhD, CISSP, S-CISO | CoFounder Responsible Cyber | @womenoncyber | Documentary The Dark Web on @myCanal