What is Secure Coding and Why is It Important?

Laptop on a table with coding icon and padlock
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Summary: What is Secure Coding and Why is It Important?

Most vulnerabilities stem from an application or program’s source code. Flaws or errors in a program’s code can be exploited easily by malicious users to take control of the program and use it for their own personal gain.

Luckily, most common software security vulnerabilities can be mitigated by following well-established secure coding standards, such as OWASP and SEI Cert. Some of the most essential components of secure coding are:

  1. Data input validation
  2. Authentication and Password Management
  3. Access Control
  4. Keep it Simple
  5. Cryptographic Practices
  6. Error Handling and Logging
  7. Data Protection
  8. Threat Modeling

Learn more about secure coding in the article below!

Vulnerable coding icon

Security vulnerability exploits show us just how vulnerable software code really can be. Software code sits at the heart of how your application works. If your code has security vulnerabilities, your entire app might be vulnerable to cyberattacks.

A quick glance at tech headlines over the past year reveals how often security vulnerabilities in software are exploited by unauthorized users.

Two big-tech companies, Apple and Google, reported vulnerabilities in their respective operating systems. Even Red Hat, an IBM subsidiary that provides open-source software, reported a vulnerability in its Linux Enterprise version that is being actively exploited.

Preventing cybersecurity incidents, which can cause leaks of sensitive data and other personal information, starts at the very beginning of the software development process with the source code itself. In this article, we go over what secure coding is, why it’s important, and what the top secure coding practices are.

What is Secure Coding? Why is Secure Coding Important?

Coding icon with a padlockCoding, or computer programming, is the practice of designing executable programs in a language that can be interpreted by your computer. When a software developer writes this source code, they need to consider many things, such as:

  • Architecture and design requirements of the application
  • Code optimization and efficiency
  • Code security and safety

Secure coding makes it easier for developers and programmers to weed out common vulnerabilities in their software by following certain best practices and guidelines, known as secure coding standards.

The adoption of secure coding practices is important because it removes commonly exploited software vulnerabilities and prevents cyberattacks from happening. Moreover, optimizing for security from the start helps reduce long-term costs which may arise if an exploit results in the leak of sensitive information of users.

Despite the importance of coding in a secure manner, software vulnerabilities are rampant. A search using the National Institute of Standards and Technology (NIST) vulnerability list shows that there have been 40,569 application vulnerabilities in the last three years alone.

We’ve listed some of the best secure coding practices below in an attempt to reduce software vulnerability and make computer programs safer for everyone!

How Do You Code Securely?

There is abundant literature on secure coding best practices. For example, The Open Web Application Security Project (OWASP) has created a set of guidelines that help developers mitigate common software security vulnerabilities. Similarly, the SEI CERT secure coding standards lay down ten secure coding best practices that programmers can incorporate to maximize application security.

We have distilled some of the most relevant practices from both these sources:

Infographic showing how to code securely


1. Data input validation

This covers numerous aspects of data source and input validation. Most threats to cybersecurity come from external data inputs in the form of cross-site scripting, buffer overflows, and injection attacks.

Hence, it is crucial to establish security practices that govern which sources are trusted and how data from untrusted sources will be verified.


2. Authentication and password management

Limiting access of the program to authorized users is an effective way to prevent cyber-attacks and data breaches. Some best practices for authentication and password management include:

  • Using a trusted system for password hashing
  • Enforcing password length and complexity requirements
  • Storing authentication credentials on a trusted server
  • Using multi-factor authentication

3. Access control

Access control goes hand in hand with authentication to ensure that a malicious user cannot easily gain access to the targeted system. As a general rule, it is best to adopt a default-deny approach, which means that users who cannot demonstrate authorization should be denied access. For web applications that entail extended log-in periods, the code should require periodic re-authorization for sustained access.


4. Keep it simple

While this may not be intuitive, keeping your code simple and clean is a great way of ensuring its security. This is because complex designs increase the likelihood that vulnerabilities will creep into the code. Developers should avoid unnecessary complexities while writing software and include only what is essential.


5. Cryptographic practices

The secure coding standards mentioned above stress the importance of implementing effective cryptographic processes to protect secrets from the application user. All random values generated as part of the cryptographic process should be generated using an approved random number generator to ensure that they are unguessable.


6. Error handling and logging

Even the most well-written code is likely to run into errors. What’s important is that when an error crops us, it is identified and dealt with at the earliest to contain its impact.

The accurate identification of errors depends on effective logging of all events that occur in the code. Developers can access these logs to diagnose any errors that may have arisen. But be careful not to include any sensitive information in the error messages or logs!


7. Data protection

The objective of most cyber attacks is to access sensitive data. Hence, it comes as no surprise that data protection is an important aspect of secure coding requirements. Some useful tips for effectively protecting data include:

  • Adherence to the principle of least privilege, i.e. elements of the code should execute with the least set of privileges necessary to complete the job
  • Regular deletion of temporary or cached copies of sensitive stored on the server
  • Not storing passwords and connection strings in clear text or any non-encrypted manner on the client-side

8. Threat modeling

It’s difficult, if not impossible, to protect yourself against threats you aren’t aware of. This is why threat modeling is so important. It involves identifying potential threats and then defining countermeasures to prevent or mitigate them from occurring. A threat modeling exercise should be carried out on a regular basis to ensure that any new risks are not left out.


9. Beyond coding

Implementing the above guidelines should help weed most vulnerabilities that stem from the code itself. However, ensuring that your code is secure is an ongoing process and requires constant vigilance. Other areas that need to be part of a holistic approach to creating secure code include:

  1. A system based on “least privilege”: Keeping access to any code on a need-to-know basis will help prevent any injection attacks. This can be particularly tricky when using outsourced developers or development companies.
  2. Defense in depth: Keep on layering defensive strategies as the code gets promoted through to production. Make sure your runtime environments are as secure as your code.
  3. Practice good quality assurance: Use various assurance programs such as code reviews and PEN testing to ensure quality.
  4. Understand how to apply the Software Development Life Cycle (SDLC) to secure coding. Using an SDLC approach will help you to ensure that security filters through all parts of the development lifecycle.

Resources for Successful Secure Coding

Keeping your development team trained and in touch with the latest secure coding standards is crucial to secure coding. You can’t expect programmers to know how to code securely from the get-go. Instead, they need to be trained and made aware of the different secure coding practices, as well as the common security vulnerabilities.

Below are some useful resources to help you and your team on a path to creating secure code.

ResourceDescription
OWASP Developer GuideA useful foundation stone to help developers avoid common software programming errors. Also, check out their tool that looks for dependencies and publicly disclosed vulnerabilities that might impact your project.
Microsoft’s Bible on Secure CodingLike OWASP and SEI Cert, Microsoft has also put together a guide on secure coding practices for developers who are creating software for its products. The guide covers each stage of the software development lifecycle and is very comprehensive.
OWASP Security Knowledge Framework The OWASP SKF is an open-source web application that explains secure coding practices in different programming languages. It’s a great way to get you and your team up to speed with the basics of secure coding regardless of which language you’re using.
CheckMarx and CAST SoftwareBoth CheckMarx and CAST are examples of companies that will analyze and study your code to identify potential security vulnerabilities. If you have little to no experience with secure coding, it would be a good idea to use their services to ensure the security and robustness of your source code.
RedHat Tutorials Tutorials are a great way to get your team started with secure coding practices. RedHat offers tutorials that cover the basics of input validation, authorization, and other secure coding practices.

Secure Code for a Competitive Edge

Security starts with your code, and creating secure code is a vital part of creating a great software product.

Insecure coding practices not only leave your customers at risk, but they will impact the reputation of your company. Applying the tenets of the SEI CERT and OWASP secure coding guidelines is a good place to start. Producing demonstrably secure software can not only allow you to prevent cyber-attacks but give your organization a competitive edge.

Secure Coding: Frequently Asked Questions

Secure Coding can be a complex topic with a lot of technical jargon, making it difficult for the average user to understand it easily. To remedy this, we’ve provided answers to some of the most frequently asked questions regarding secure coding in the section below.

Do let us know if we missed anything using the comments!

Code refers to the set of instructions that define how a computer program will run. Code is written by developers using programming languages, such as Java and Python.

While writing this code, developers can sometimes inadvertently make errors or leave gaps that make the software vulnerable to exploitation by unauthorized users. These errors or gaps can make code insecure.

Using secure coding standards is a systematic and practical approach to weeding out any common software vulnerabilities from your code. By following standards such as OWASP and SEI CERT, you can make your software more secure for users and avoid legal and financial complications that could result from any exploits, hacks or breaches.

We would say the following elements are critical to secure coding, based on our study of credible secure coding standards, such as OWSAP and SEI CERT:

  1. Input Validation
  2. Access Control
  3. Authentication and Password Management
  4. Threat Modeling
  5. Data Protection
  6. Cryptographic Practices
  7. Error Handling and Logging
  8. Keeping it simple

For more information on each of these, please refer to our article on secure coding.

Research suggests that Ruby is one of the most secure programming languages, as it has faced the least number of security vulnerabilities over the last decade. Python is also pretty secure and has shown a declining trend of vulnerabilities since 2015.

Corporate IT security expert
Susan has been involved in the IT security sector since the early nineties, working across diverse sectors such as file encryption, digital rights management, digital signing, and online identity. Her mantra is that security is about human beings as much as it is about technology.