Popular with:
Security Engineer
Application Security

The Art of Secure Coding

March 14, 2024
Written by
Vishnu Prasad K

The security of software is as important as its functionality.  For developers, writing secure code is not just a skill but a necessity to protect software from these frequent cyber threats. Recent data supports the severity of this issue. According to a study by the University of Maryland, the frequency of cyber attacks is alarmingly high, with an average of 2,244 attacks happening daily. The IBM Cost of Data Breach Report 2023 revealed that the average cost of a data breach had reached $4.45 million, a number that continues to grow each year.

This blog aims to encourage developers to acquire secure code training to guide them through building robust software against the threat of cyber attacks. We will dive into the essentials of secure coding, from understanding common vulnerabilities to implementing best practices that can significantly reduce the risk of a security breach. By the end of this blog, you will be equipped with actionable knowledge to enhance the security of your code in building robust and secure software against cyber attacks.

Table of Contents

Defining Secure Coding in modern software development

#1 Principle of least privilege

#2 Input validation and sanitization

#3 Secure authentication and session management

#4 Encryption and secure data handling

#5 Error handling and logging

#6 Regular code reviews and audits

#7 Staying updated with security trends and threats

#8 Secure coding standards and frameworks

#9 Continuous learning and improvement

Improve your secure coding skills now!

Defining Secure Coding in modern software development

Secure coding is the practice of writing software in a way that protects it from vulnerabilities. This practice is crucial in software development because it directly addresses the increasing concerns of cyber threats and security breaches. Secure coding is not just about fixing bugs after they are discovered; it's about proactively designing and writing code to prevent security vulnerabilities from occurring in the first place.

In a world where no one is safe from being hacked, your teams need secure code training to ensure that software is robust against attacks, thus safeguarding sensitive data and maintaining user trust. It involves adhering to a set of coding standards and best practices that aim to eliminate errors that could lead to security vulnerabilities.

The primary role of secure code training is to allow your teams to have the ability to prevent security vulnerabilities that can be exploited by attackers. These vulnerabilities happen often because of common coding errors, such as buffer overflows, SQL injection, cross-site scripting, and failure to handle errors securely.

Now, let's talk about the fundamentals of secure coding so you can have a comprehensive understanding of how to fortify your code from design to deployment.

#1 Principle of least privilege

The Principle of Least Privilege (PoLP) is a fundamental concept in computer security and coding practices. It states that a user, program, or process should have only the minimum privileges necessary to perform its function. This is important for minimizing the risk of unauthorized access and limiting the damage that can occur from accidents, errors, or malicious attacks.

In software development, applying the Principle of Least Privilege helps to reduce the attack surface of your applications. Ensure that components of your software operate with only the permissions they absolutely need to prevent a wide range of security vulnerabilities.

How to implement the principle in coding practices

  1. User access control. When designing software that requires user authentication, assign the least amount of privilege necessary for users to perform their tasks. For instance, a regular user should not have administrative privileges.
  2. Process privileges. Make sure that your software's processes and services run with the least privilege necessary. Avoid running processes as root or administrator unless absolutely necessary.
  3. Code execution. Apply the principle to the execution of code. For example, if a script only needs to read from a database, it should not have the privilege to modify the database.
  4. Secure defaults. Design your software with secure defaults. A new user or process should start with minimal privileges and only gain more as required and explicitly granted.
  5. Regular audits. Regularly review and audit your code and systems to ensure that privileges are correctly assigned and no unnecessary privileges are granted.
  6. Error handling. Implement robust error handling that doesn't inadvertently elevate privileges or disclose sensitive information.
  7. Dependency management. Be cautious with third-party dependencies and ensure they also adhere to the principle of least privilege.

#2 Input validation and sanitization

Unvalidated and unsanitized input is a major security risk in software development. When input is not properly checked or cleaned, it can lead to various types of attacks, most notably SQL injection, cross-site scripting (XSS), and command injection. These attacks can result in unauthorized access to data, data corruption, and even complete system compromise.

Techniques for effective input validation

  1. Define acceptable input. Clearly specify what constitutes valid input in terms of format, type, and length, such as setting strict patterns for data like phone numbers, email addresses, and user IDs.
  2. Reject invalid input. Inputs that do not meet the validation criteria should be rejected outright. This is often more secure than trying to sanitize or correct invalid inputs.
  3. Use built-in functions. Many programming languages and frameworks provide built-in functions for input validation. Utilize these functions as they are often well-tested and regularly updated.
  4. Client-side and Server-side validation. Implement validation both on the client-side for user convenience and on the server-side for security, as client-side validation can be bypassed.

Sanitization practices

  1. Data sanitization. Remove or replace characters in the input that are not required or could be harmful, including stripping out HTML tags, JavaScript code, and SQL syntax.
  2. Use whitelisting. Where possible, use whitelisting to allow only pre-approved input. This is generally more secure than blacklisting, which tries to anticipate harmful input.

#3 Secure authentication and session management

Secure authentication and session management are critical for protecting user data and maintaining the integrity of your application.

Best practices for user authentication

  1. Strong password policies. Enforce policies that require complex passwords, combining letters, numbers, and special characters. Regularly prompt users to change their passwords.
  2. Multi-factor authentication (MFA). Implement MFA to add an extra layer of security. This could include something the user knows (password), something the user has (a mobile device), or something the user is (biometrics).
  3. Account lockout mechanisms. Implement account lockout mechanisms after a certain number of failed login attempts to prevent brute force attacks.
  4. Use HTTPS. Always use HTTPS, not HTTP, for transmitting login information to prevent man-in-the-middle attacks.
  5. Password hashing and salting. Store user passwords as hashed values with a unique salt for each password to make it difficult for attackers to use rainbow tables to crack the passwords.
  6. Rate Limiting. Implement rate limiting on login attempts and other sensitive operations to prevent automated attacks and reduce the risk of brute force attempts, for example, limiting the number of requests a user can make within a certain timeframe.

Techniques for secure session management

  1. Session timeouts. Implement session timeouts to automatically log users out after a period of inactivity.
  2. Secure cookies. Use secure and HttpOnly flags for cookies to prevent them from being accessed through client-side scripts to reduce the risk of XSS attacks.
  3. Regenerate session IDs. Regenerate session IDs after login to prevent session fixation attacks.
  4. Token validation. Validate tokens or session IDs at every request to ensure they are still valid and have not been tampered with.

#4 Encryption and secure data handling

Encryption plays an important role in secure coding by transforming data into a format that is unreadable to unauthorized users. It is a key defense mechanism against data breaches to ensure that even if data is intercepted or accessed without permission, it remains confidential and intact. Encryption is particularly crucial for protecting sensitive information such as user credentials, personal data, and financial information.

Best practices for data encryption and secure data storage

  1. Use strong encryption standards. Employ robust encryption algorithms like AES (Advanced Encryption Standard) for encrypting data. Avoid using outdated or weak encryption methods.
  2. Encrypt data at rest and in transit. Ensure that data is encrypted not only when it is being transmitted over networks but also when it is stored on servers or databases.
  3. Manage encryption keys securely. Store encryption keys separately from the data they encrypt. Use secure key management systems and regularly rotate keys.
  4. Implement SSL/TLS. Use SSL/TLS protocols for securing data transmission over the internet. Ensure that you are using the latest versions to avoid vulnerabilities.
  5. Regularly update security protocols. Stay updated with the latest security patches and updates for your encryption software and protocols.

Encryption algorithms and their appropriate use cases

  1. AES (Advanced Encryption Standard). Widely used for encrypting data at rest. It is known for its speed and security and is commonly used in government and financial institutions.
  2. RSA (Rivest-Shamir-Adleman). A public-key encryption algorithm used for secure data transmission. Ideal for scenarios where data needs to be encrypted by one party and decrypted by another.
  3. SHA (Secure Hash Algorithm). Used for creating a unique hash value for data. It’s commonly used for password hashing but should not be used alone for password storage due to vulnerabilities.
  4. TLS (Transport Layer Security). A protocol that ensures privacy between communicating applications and their users on the internet. Used for securing web browsers, email, and other communication channels.

Get the skills to build secure software: Explore our Secure Coding Collection

#5 Error handling and logging

Proper error handling is crucial for software security as it prevents the leakage of sensitive information and ensures that the system remains stable and reliable even when unexpected situations occur. Good error handling practices can thwart many common security issues, such as Denial of Service (DoS) attacks.

Best practices for secure and informative logging

  1. Log enough information. Ensure that logs contain enough information to understand the context and cause of errors, such as timestamps, error codes, and a brief description of the error.
  2. Avoid logging sensitive information. Never log sensitive data like passwords, personal identification information, or encryption keys.
  3. Use structured logging. Structured logs are easier to process and analyze. They help in quickly identifying patterns or anomalies in the system.
  4. Implement log rotation and retention policies. Regularly rotate logs to manage disk space and set retention policies that comply with legal and privacy requirements.
  5. Monitor and alert. Set up monitoring on your logs to alert the team in case of critical errors or suspicious activities.

Balancing between informative logging and data protection

Balancing informative logging with data protection involves ensuring that logs provide enough detail for troubleshooting and analysis while not exposing any sensitive information. This can be achieved by masking or redacting sensitive information in logs, restricting access to logs to authorized personnel only, and conducting regular audits of your logs and logging practices to ensure they comply with security policies and data protection laws.

#6 Regular code reviews and audits

Code reviews play a crucial role in identifying security flaws within software. They involve a systematic examination of source code by one or more individuals who look for errors, vulnerabilities, and deviations from best practices. The primary goals of code reviews in the context of security are:

  • Identifying common vulnerabilities. Code reviews help in spotting common security issues like SQL injection, cross-site scripting (XSS), and buffer overflows.
  • Ensuring compliance with coding standards. Reviews ensure that the code adheres to established secure coding standards and practices.
  • Knowledge sharing. They facilitate the sharing of knowledge and best practices among team members, which leads to more secure coding habits.

How to conduct effective security audits

  1. Define audit objectives. Clearly outline what you are looking to achieve with the audit, whether it's compliance, security vulnerability identification, or performance checks.
  2. Use a checklist. Develop a checklist based on common security vulnerabilities and industry best practices to guide the audit process.
  3. Involve diverse team members. Include team members with different expertise and perspectives to ensure a comprehensive audit.
  4. Document findings. Keep a record of all findings and recommendations for future reference and compliance purposes.
  5. Create an action plan. Develop a plan to address the identified issues and monitor the implementation of these changes.

Tools and techniques for automated code review

  1. Static Analysis Tools. Utilize static application security testing (SAST) tools that can automatically analyze source code for potential security vulnerabilities without executing the program. Examples include SonarQube, Fortify, Semgrep, CodeQL and Checkmarx.
  2. Dynamic Analysis Tools. Employ dynamic application security testing (DAST) tools that test the application during runtime to find vulnerabilities that are difficult to detect in static analysis. Tools like OWASP ZAP and Burp Suite are popular choices.
  3. Code linters. Use linters specific to your programming language, which can help identify potential security issues, coding errors, and deviations from coding standards.
  4. Dependency scanners. Implement tools that scan for vulnerabilities in third-party libraries and dependencies. Tools like OWASP Dependency-Check can be very useful in identifying known vulnerabilities in used components.
  5. Integration into CI/CD pipeline. Integrate these tools into your Continuous Integration/Continuous Deployment (CI/CD) pipeline for continuous and automated scanning of code changes.
  6. Peer review automation. Use tools that facilitate peer code reviews, such as GitHub's pull request reviews or GitLab's merge request reviews, which can be automated to require reviews for certain types of changes.
  7. Custom rules and templates. Customize the rules and templates in these tools to align with your organization's specific coding guidelines and security policies.
  8. Regular updates and training. Ensure that the tools are regularly updated and that the team is trained on how to use them effectively and interpret their results.

#7 Staying updated with security trends and threats

Staying informed about the latest threats and trends is crucial in the rapidly evolving field of cybersecurity. Cyber threats are constantly changing and becoming more sophisticated, which makes outdated security knowledge ineffective against new attacks. By staying updated, developers and security professionals can:

  1. Anticipate and prepare for emerging threats. Understanding new types of cyberattacks allows developers to anticipate potential vulnerabilities and take proactive measures to protect their systems.
  2. Ensure compliance. Staying informed about the latest security standards and regulations ensures that software remains compliant with legal and industry requirements.
  3. Maintain software integrity. Regular updates in security knowledge help in maintaining the integrity and reliability of software products.

Resources for staying informed about security trends

  1. Security blogs and websites. Follow reputable cybersecurity blogs and websites like Krebs on Security, Schneier on Security, and The Hacker News for the latest updates and analyses.
  2. Online forums and communities. Engage with online communities such as Stack Exchange's Information Security community, Reddit's r/netsec, or OWASP chapters for discussions and insights.
  3. Webinars and conferences. Attend webinars and conferences like DEFCON, Black Hat, and RSA Conference to learn from experts and network with other professionals.
  4. Security newsletters. Subscribe to newsletters from cybersecurity firms or organizations for regular updates in your inbox.
  5. Training and certification courses. Enroll in courses and obtain certifications that focus on the latest security practices and technologies.

Incorporating new security measures into existing coding practices

  1. Regular training. Conduct regular training sessions for your development team to ensure they are aware of the latest security threats and best practices.
  2. Update security policies. Regularly review and update your organization's security policies and guidelines to reflect the latest security trends.
  3. Code review and audits. Incorporate new security measures into your regular code reviews and audits to check for compliance with the latest security standards.
  4. Use of updated tools. Utilize the latest tools and technologies for security testing and monitoring to ensure that they are updated to detect the latest vulnerabilities.
  5. Feedback loop. Create a feedback loop where developers can share insights and experiences related to new security threats and solutions.

#8 Secure coding standards and frameworks

Adhering to secure coding standards and leveraging the security features of various frameworks are essential practices for developing secure applications. These standards and frameworks provide a foundation for writing code that is resilient against common security threats, thereby enhancing the overall security posture of software products.

OWASP (Open Web Application Security Project)

OWASP is a widely recognized authority on web application security. It provides comprehensive guidelines, tools, and resources to understand and mitigate common web application vulnerabilities. The OWASP Top Ten is a standard awareness document representing the most critical security risks to web applications.

CERT (Computer Emergency Response Team)

CERT offers coding standards for various programming languages that focus on security and reliability. Their standards provide detailed recommendations on how to write secure code and avoid common mistakes that lead to vulnerabilities.

The role of frameworks in enforcing secure coding practices

Built-in security features

Many modern frameworks come with built-in security features that align with secure coding standards. For example, frameworks like ASP.NET, Spring, and Ruby on Rails have built-in protections against common vulnerabilities like SQL injection and cross-site scripting (XSS).

Standardized coding practices

Frameworks often enforce standardized coding practices, which can help in maintaining a consistent approach to security across the development team.

Community and support

Popular frameworks usually have a large community and extensive documentation, providing support and guidance on implementing secure coding practices.

Regular updates and patches

Frameworks are regularly updated to address security vulnerabilities, and using them can ensure that applications benefit from these updates.

#9 Continuous learning and improvement

Stay informed, adapt to new threats, and foster a culture of ongoing education to better protect your organization against the ever-changing landscape of cybersecurity threats.

The importance of adapting and evolving security strategies

Cybersecurity is a field that is constantly changing, with new threats emerging regularly. It's important for organizations and developers to:

  1. Stay agile. Be ready to adapt and update security strategies in response to new threats and vulnerabilities.
  2. Implement feedback loops. Create mechanisms to learn from security incidents and integrate those learnings into future strategies.
  3. Continuous assessment. Regularly assess and update security measures and practices to ensure they are effective against current threats.
  4. Proactive approach. Encourage a proactive approach to security, where potential threats and vulnerabilities are anticipated and mitigated before they can be exploited.

Improve your secure coding skills now!

A cyber attack occurs every 39 seconds. The need for proactive security measures is more important than ever because of this.

The Secure Coding Collection by AppSecEngineer offers a comprehensive approach to secure product development, adaptable to any tech stack. Covering critical OWASP Top 10 vulnerabilities, encryption, authentication, API security, and secure coding in over eight languages, it provides an unmatched combination of courses, hands-on labs, Playgrounds for coding in various languages like Python, Java, Ruby, and more, and Challenges to evaluate skills. 

Secure coding is an integral part of software development that demands constant vigilance, updating of skills, and adaptation to new challenges. But how can you do it without proper training?

Source for article
Vishnu Prasad K

Vishnu Prasad K

Vishnu Prasad is a DevSecOps Lead at we45. A DevSecOps and Security Automation wizard, he has implemented security in DevOps for numerous Fortune 500 companies. Vishnu has experience in Continuous Integration and Continuous Delivery across various verticals, using tools like Jenkins, Selenium, Docker, and other DevOps tools. His role sees him automating SAST, DAST, and SCA security tools at every phase of the build pipeline. He commands knowledge of every major security tool out there, including ZAP, Burp, Findsecbugs, and npm audit, among many others. He's a tireless innovator, having Dockerized his entire security automation process for cross-platform support to build pipelines seamlessly. When AFK, he is either pouring over Investment journals or in the swimming pool.

Vishnu Prasad K


Contact Support


1603 Capitol Avenue,
Suite 413A #2898,
Cheyenne, Wyoming 82001,
United States

Copyright AppSecEngineer © 2023