Main takeaways from this article:
Secure coding tackles vulnerabilities like XSS and memory leaks early, boosting software resilience and reducing risks.
Proactive practices save time and money by preventing costly post-release fixes and fostering user trust.
Best practices include validating inputs, securing third-party code, and leveraging tools like SAST for continuous checks.
Standards from OWASP, CERT, and NIST help developers build secure, reliable applications.
Wiz Code supports secure coding with real-time scans, actionable feedback, and guidance to safeguard your SDLC.
What is secure coding?
Secure coding is the practice of developing software that is resistant to security vulnerabilities by applying security best practices, techniques, and tools early in development. Instead of thinking only about user experience, secure coding aligns every feature with security measures—right from the beginning of the software development lifecycle.
For example, an application that accepts all data from a client without sanitizing it might be easier to implement, use, and maintain. However, it opens an entry point for attackers to inject malicious code.
The Secure Coding Best Practices [Cheat Sheet]
With curated insights and easy-to-follow code snippets, this 11-page cheat sheet simplifies complex security concepts, empowering every developer to build secure, reliable applications.
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Why is secure coding important?
Secure coding embeds security into your software’s DNA to prevent vulnerabilities like SQL injection, buffer overflows, cross-site scripting, and more. Beyond just preventing breaches, it’s a way to safeguard user trust, shift security left, and meet the tough standards of data protection laws.
The payoff? Fewer nasty surprises after launch, stronger apps, and better protection for both users and your organization.
Seven secure coding techniques for building secure software
A secure software development process starts with following the right coding practices that help prevent vulnerabilities and keep your applications safe. If you're looking for a more in-depth resource, be sure to check out the OWASP secure coding requirements in their Developer Guide.
In the meantime, here are some key techniques you can start using right away to build more secure software systems:
1. Use modern languages and tools
Many memory-related security vulnerabilities affect programming languages with manual memory management and no built-in memory checks. When starting a new project, make sure you really require C/C++ for it, and if you do, use smart pointers and static code analyzers to minimize the impact of language flaws.
If you need system programming features, a more modern language like Rust can be a good choice because its type system checks memory use at compile time. Zig might also be a good alternative, as it has no hidden control flow or memory allocations.
If you don’t need system programming features, using a garbage-collected language like Java or C# can protect you from many memory issues.
2. Validate and sanitize input and output data
Unvalidated user data is the prime reason for injection flaws. That’s why it’s critically important to validate all data that enters your system. Sanitation is another step that can keep security in check without sacrificing usability. Instead of rejecting a user input if it’s invalid, sanitation will cut out problematic input parts (i.e., JavaScript inside HTML) and use the remaining data. When running in a client-server environment, ensure this validation and sanitation happens on the server. This means adding validators and sanitizers to all API endpoints that accept user data. It can also mean choosing data formats that are easy to validate—for example, accepting simple Markdown instead of fully-fledged HTML.
Keeping input data clean isn’t always possible; validation libraries have bugs, too. To ensure nothing leaks through to your users, only display outputs based on user inputs in a secure way (i.e., don’t render HTML).
3. Check third-party code integrity
Third-party libraries and frameworks are lifesavers for speeding up development, but they come with strings attached—they weren’t built in your house. Treat them like any input to your build process: carefully vetted and under control.
Want to avoid nasty surprises? Pin dependencies to specific versions or hashes to stop untested updates from sneaking into production. Regularly auditing and updating those libraries isn’t glamorous, but it’s the only way to avoid outdated code becoming your Achilles’ heel.
4. Enforce strict access control
Access control limits who can view or modify code and resources, protecting sensitive functions and data from unauthorized users. Stick to the principle of least privilege: give users only what they need to do their job—nothing more, nothing less.
For enhanced security, consider implementing role-based access controls (RBAC) and multi-factor authentication (MFA). These measures further reduce your attack surface and ensure that unauthorized individuals cannot access critical systems or data.
5. Implement proper error handling and logging
Nobody wants to hand attackers a roadmap, yet that’s exactly what overly detailed error messages can do. Keep internal details—stack traces and database errors, for example—out of the hands of users. Log them instead, securely and thoughtfully, for your team’s eyes only.
Good logs tell the story: what happened, when, and why. Monitor them for anything fishy, but don’t overdo it by logging sensitive data. Balance is key here—you’re troubleshooting, not exposing.
6. Automate code reviews
Manual reviews are important, but automation is necessary. Automated tools like static application security testing (SAST) and linters flag vulnerabilities and coding errors faster than humans ever could.
Hook these tools into your CI/CD pipeline, and every code change gets a once-over before it’s merged. Immediate feedback keeps developers in the loop and ensures that security best practices stay front and center.
7. Apply code obfuscation techniques
Code obfuscation doesn’t make your app bulletproof, but it slows down attackers. Renaming variables to gibberish, encoding strings, and restructuring code make it harder to reverse engineer or steal intellectual property.
Think of it as adding camouflage: the app still runs smoothly for users, but bad actors will find it much harder to break in or make sense of what they see. Every hurdle helps.
Common code software vulnerabilities
Let’s look at common security vulnerabilities software developers and security researchers have identified. We’ll go from low-level issues like memory vulnerabilities to higher-level problems like injection attacks.
Buffer overflows
Buffer overflows can crash your application or allow attackers to write data into other buffers.
System programming languages like C/C++ are prone to this vulnerability. They allow and even require memory management explicitly but don’t check memory access until it’s too late. If you write more data into a buffer than you assigned it at definition time, C will override all memory data that follows at the end of the buffer.
Example of a buffer overflow in C:
int b[5];
b[5] = 999; // buffer only goes from 0 to 4Use after free
Use after free happens when you free memory on the heap but keep using the old pointer.
Again, this vulnerability is prominent in languages without garbage collection, like C/C++, where you must manually manage memory. There are two types of memory: the stack and the heap. The language automatically manages the stack, which can’t hold data with dynamic sizes that aren’t known at compile time. The heap is for dynamic data, but you must manually allocate and free space on it. Freeing means you tell the operating system that you don’t need the memory anymore, so if you use it afterward with a pointer, the illegal access will go to an unallocated memory location.
Example of use after free in C:
char* p = (char*)malloc (16);
p = strdup("Some text!");
free(p);
printf("%s", p); //prints what’s now in the freed memoryDouble free
In the case of double free, you are freeing heap memory after you have already freed it.
Double free is an issue in languages with manual memory management, where you must explicitly tell the operating system that you no longer need a specific memory range. Doing so two times will result in a crash similar to the use after free issue. This usually happens when you have multiple objects with pointers to each other that get freed at some point. Double free can corrupt the memory a pointer referenced before the first free.
Example of double free in C:
char* p = (char*)malloc (16);
p = strdup("Some text!");
free(p);
free(p); // will corrupt what’s in the freed memoryInsecure deserialization
Insecure deserialization involves directly transforming an external data structure (e.g., JSON, XML, etc.) to an internal one (e.g., objects, arrays, etc.) without sufficient checks.
Insecure deserialization is a common vulnerability in all kinds of applications. It might be good to accept unsanitized data during development, but users can sneak in malicious data without notice if it is done in production.
Example of insecure deserialization in JSON:
{
"name": "example",
"email": "email@example.com",
"isAdmin": true // should be deleted on the server
}Memory leaks
Memory leaks let your application consume memory without bounds. If you exhaust the available memory and request more, your application will crash.
Every sufficiently complex application is susceptible to this vulnerability. Even garbage-collected languages aren’t safe from memory leaks. Garbage-collected languages still allow you to build data structures a garbage collector can’t manage.
Injection flaws
Executing user input as code without validating it is known as an injection flaw.
This issue can affect all applications, regardless of the programming language used. One way to make your application vulnerable to injection flaws is by allowing users to add custom code as a feature and not sandbox the execution properly. Buffer overflows that allow attackers to write code into executable memory locations are another way that your application can become vulnerable to injection flaws.
Cross-site scripting (XSS)
Cross-site scripting is a web-specific version of an injection flaw. Here, an attacker inserts custom JavaScript hidden inside HTML markup.
XSS can happen on all websites. Because markup and executable code are tightly integrated on the web, it’s easy to sneak JavaScript into HTML, which leaks sensitive data.
Example of XSS in HTML and JavaScript:
<!-- this will send a fetch request
when the mouse is over the <p> element -->
<p onmouseover="fetch('//example.com')">Hello, world!</p>XML external entities (XXE)
XML external entities are another instance of an injection flaw. All applications that use XML are susceptible to this attack. The idea behind external entities in XML is to allow reuse of existing XML files. However, an attacker can use this feature to include links to private XML files, allowing them to read private data indirectly through their uploaded XML file.
Example external XML entity injection:
<?xml version="1.0" encoding="ISO-8859-1"?>
<!DOCTYPE a [
<!ELEMENT a ANY >
<!-- this defines a new entity called xxe
from a private file -->
<!ENTITY xxe SYSTEM "file:///etc/passwd" >
]>
<!-- here the entity is rendered to display
the file content -->
<a>&xxe;</a>Insecure direct object reference (IDOR)
When you allow public APIs to reference objects with sequential IDs directly, IDORs can enable attackers to guess the ID of all objects on the server.
This issue can happen anywhere sequential IDs are used to reference objects and is especially serious when using the IDs to reference public and private objects without requiring authorization.
Example URLs:
https://example.com/users/4539
https://example.com/users/4540
https://example.com/users/4541
Directory traversal (aka path traversal)
Another injection flaw is where attackers can traverse paths or directory structures via file-name inputs.
All applications that allow file name inputs can become a victim of this vulnerability. Directory traversal can happen when users upload multiple files referencing each other via relative paths. Attackers can use file traversal paths like ".." to navigate from their upload directory on the server and into directories with files from admins or other users.
Example of directory traversal in JavaScript on Node.js:
// This loads a private javascript file
const template = require("../../../server/config/database")
render(template)Code security standards
Secure coding standards are sets of guidelines and best practices that developers follow to create secure software and minimize vulnerabilities. They address common coding mistakes and weaknesses that can be exploited by attackers, aiming to create more resilient and resistant code.
Below are the common secure code standards to follow:
1. OWASP Secure Coding Practices:
OWASP Secure Coding Practices (SCP) are guidelines by the Open Web Application Security Project that focus on key areas to improve software security, such as input validation, authentication, session management, encryption, and error handling. It’s a roadmap for safer code, from your first commit to final deployment.
2. CERT Secure Coding Standards:
CERT Secure Coding Standards (SCS) are a set of guidelines and recommendations developed by the Software Engineering Institute (SEI) at Carnegie Mellon University to help developers write secure code and prevent vulnerabilities. Key areas of focus:
Language-specific guidelines: Offering recommendations for C, C++, Java, Android, and Perl to address common vulnerabilities in those languages.
Defensive programming: Emphasizing anticipating and handling errors gracefully to prevent exploitation.
Memory management: Focus on preventing buffer overflows and memory leaks, especially in languages like C and C++.
3. NIST Secure Coding Guidelines:
NIST Secure Coding Guidelines (also known as NIST Special Publication 800-218) focus on critical areas like input validation, authentication, encryption, and error handling, offering clear advice to keep injection attacks, session hijacking, and memory problems out of your software. If you want a government-backed stamp of approval on your code security practices, this is your go-to.
ISO/IEC 27001 is an international information security standard. While it's not specifically a secure coding standard, it does include requirements for secure coding practices as part of a comprehensive security management approach. Annex A, Control 8.28: Secure Coding Practices, specifically focuses on secure coding and emphasizes how organizations must:
Develop secure coding processes for in-house development and third-party code.
Stay informed about evolving threats and vulnerabilities.
Implement robust secure coding principles to address them.
Ensure a secure software development life cycle with Wiz
Secure coding is a practice that touches all aspects of software development—from choice of data formats and programming languages to planning of inputs and outputs to implementation.
We're excited to introduce Wiz Code, our latest innovation designed to empower developers and security teams to implement and maintain robust secure coding practices throughout the entire software development lifecycle!
Wiz Code extends our cloud security platform to cover every stage of development, offering powerful capabilities to support your secure coding initiatives:
Integrated Code Scanning: Detect vulnerabilities, misconfigurations, and compliance issues directly in your IDE and code repositories, catching potential problems before they reach production.
Real-Time Security Feedback: Get instant security insights as you code, enabling developers to address issues immediately and learn secure coding practices on the go.
Cloud-to-Code Traceability: Trace risks discovered in production environments back to the specific code and teams that introduced them, facilitating rapid root cause analysis and remediation.
In-Code Remediation Guidance: Receive actionable, context-aware recommendations for fixing security issues right within your development environment.
Comprehensive Language Support: Benefit from secure coding best practices across a wide range of programming languages and frameworks.
Secure your SDLC from start to finish
See why Wiz is one of the few cloud security platforms that security and devops teams both love to use.
