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Software vulnerabilities pose serious security and business risks. Writing secure code prevents these issues by integrating security into the development process. Instead of fixing vulnerabilities after deployment, developers apply secure coding practices from the start, reducing risk and building stronger, more resilient applications.
Here’s a guide to what secure coding is and how to integrate it.
What Is Secure Coding?
Secure coding is the process of writing software that reduces security risks by eliminating vulnerabilities at the code level. It follows established secure coding practices from the Open Worldwide Application Security Project (OWASP) and National Institute of Standards and Technology (NIST) to build applications that can withstand threats like SQL injection, cross-site scripting (XSS), and buffer overflows.
Adding security after development isn't enough. It should be part of the foundation. A strong approach to coding security validates user input, enforces strict access controls, and protects sensitive data throughout the software development lifecycle (SDLC).
Why Is Secure Coding Important?
Poorly written code has real-world consequences, from exposing sensitive data to disrupting critical infrastructure. Many industries—especially finance, healthcare, and software as a service (SaaS)—rely on security coding to maintain compliance and protect user trust.
Attackers frequently exploit weaknesses in authentication, data handling, and access controls, making insecure coding a primary risk factor for cyber incidents. Security teams can reduce attack surfaces by prioritizing secure coding for developers and prevent common threats like injection flaws, broken authentication, and security misconfigurations.
Beyond security, embedding safe coding techniques into development reduces long-term costs. Fixing vulnerabilities after deployment is significantly more expensive than addressing them during coding. Applying security practices throughout the SDLC strengthens defenses early and designs applications to resist threats at every stage.
Common Types of Code Software Vulnerabilities
Security vulnerabilities in code create opportunities for attackers to manipulate applications, steal sensitive data, or take control of systems. Below are some of the most common vulnerabilities developers should recognize and mitigate:
Buffer Overflows
A buffer overflow occurs when a program writes more data into a memory buffer than it was designed to hold. This can overwrite adjacent memory, causing application crashes or allowing attackers to execute arbitrary code.
Example: A C program allocates a buffer with a fixed size but doesn’t check input length, enabling an overflow that could overwrite return addresses in memory.
Insecure Deserialization
Insecure deserialization happens when untrusted data is converted into objects without proper validation. Attackers can manipulate serialized objects to execute malicious code or escalate privileges.
Example: A web application deserializes user-supplied data without checking its integrity, allowing an attacker to modify the serialized object and execute unauthorized actions.
Code Injection Flaw
Code injection vulnerabilities occur when an application interprets untrusted user input as executable code, allowing unauthorized commands to run on the server.
Example: A vulnerable PHP script concatenates user input into a system command.
Cross-Site Scripting (XSS)
XSS allows attackers to inject malicious scripts into web applications, which execute in the victim’s browser. This can lead to session hijacking, credential theft, or website defacement.
Example: A hacker injects JavaScript into a comment field, which executes when a user loads the page.
SQL Injection
SQL injection happens when an application improperly handles user input in database queries, allowing attackers to access, modify, or delete sensitive data.
Example: A login form constructs a query using unvalidated input to bypass authentication and steal data.
Broken Authentication and Session Management
Poor authentication mechanisms allow attackers to impersonate users, hijack sessions, or bypass access controls.
Example: A web application stores session tokens in predictable cookie values, allowing attackers to guess or steal them to gain unauthorized access.
Security Misconfiguration
Misconfigured security settings can expose applications to attacks. Default credentials, unnecessary features, or misconfigured access controls often create these vulnerabilities.
Example: An application ships with default admin credentials (admin/admin), allowing attackers to log in and control the system.
XML External Entity (XXE) Injection
XXE attacks exploit vulnerabilities in applications that parse XML input, allowing attackers to read files, access internal systems, or cause denial-of-service conditions.
Example: An XML parser loads an external entity that retrieves a system file without permission.
Path Traversal (Directory Traversal)
Path traversal flaws give attackers access to unauthorized files by manipulating file paths in user input.
Example: A web app allows users to download files but doesn’t sanitize input, which exposes system files.
5 Secure Coding Techniques
Implementing secure coding techniques helps prevent vulnerabilities, protect sensitive data, and keep applications resilient against cyber threats. Below are five essential techniques that strengthen security throughout the SDLC:
1. Apply Code Obfuscation
Transform source code into an unreadable format, making it difficult for attackers to analyze and reverse engineer it. This is especially useful when protecting proprietary logic in client-side JavaScript, mobile applications, and embedded systems.
Obfuscation works best when combined with other security measures, such as encryption and access controls, as part of a layered security approach. But while it raises the bar for attackers, determined adversaries can still reverse-engineer obfuscated code with enough time and resources.
2. Use Strong Encryption for Data Protection
Encrypt sensitive data in transit and at rest using industry-standard cryptographic algorithms like Advanced Encryption Standard (AES)-256 and RSA, protecting the data even if compromised — regardless of programming language. Weak encryption methods or improper key management can expose user credentials, financial data, and confidential information. Always store encryption keys securely and avoid hardcoding them in source code.
3. Conduct Peer Code Reviews and Automated Scanning
Manual peer reviews catch logic flaws and coding errors that developers and automated tools might miss. Combined with static and dynamic analysis tools (SAST/DAST), regular reviews detect vulnerabilities before deployment.
4. Implement Secure API Design
APIs serve as application entry points, making them prime targets for exploitation. Secure API practices include enforcing authentication, rate limiting, and restricting unnecessary data exposure. Proper API security prevents unauthorized access and data leaks.
5. Use Threat Modeling to Identify Risks Early
Threat modeling helps developers map out potential attack vectors before writing code. Incorporating this practice early in the SDLC reduces the cost and impact of security flaws.
To effectively utilize threat modeling, incorporate it as a continuous, "living" process throughout the SDLC, revisiting and updating threat models as the application evolves. Employ established methodologies like STRIDE (Spoofing, Tampering, Repudiation, Information Disclosure, Denial of Service, and Elevation of Privilege) or PASTA (Process for Attack Simulation and Threat Analysis) to structure your analysis and ensure comprehensive coverage.
Enhance Secure Coding With Legit Security
Secure coding requires continuous enforcement, automation, and real-time risk detection. Legit Security strengthens application security by automating security scans, protecting CI/CD pipelines, and identifying real-time vulnerabilities.
By integrating seamlessly into development workflows, Legit keeps security a core focus throughout the SDLC. Our comprehensive security platform helps teams enforce industry-recognized coding standards, detect misconfigurations, and prevent security breaches before they reach production. Implement secure coding principles while maintaining development speed and agility. Book a demo today.