Secure Code: 8 Ways to Build More Secure Software

What Is Secure Coding? 

Secure coding involves developing code securely and eliminating vulnerabilities throughout the entire software delivery lifecycle (SDLC). Secure coding is the first line of defense against cyber attacks. It typically requires: 

• An understanding of all vulnerabilities associated with the relevant host environments and integrations. 
• Language-specific knowledge of exploitable issues. 

It is impossible to control all variables that can potentially lead to vulnerabilities in environments or integrations. However, developers can exert more control over their source code. The fewer vulnerabilities in the code, the more secure the application and users become.

For teams adopting DevSecOps methodologies, secure coding is a requirement rather than a suggestion. By eliminating vulnerabilities in code during early development phases, teams can avoid the high costs and effort involved with patching issues in production.

We’ll present 8 ways to improve the security of your software – four secure coding standards that can help developers improve their development process, and four critical best practices to help create a secure coding environment.

This is part of a series of articles about vulnerability management.

In this article:

• Why Is Secure Coding Important?
• Code Vulnerabilities and Threats
• Malicious Code
• Code Injection
• Buffer Overflow Attacks
• Cross-Site Scripting (XSS)
• 4 Secure Coding Standards
• 4 Critical Secure Coding Best Practices
• Code Minification and Obfuscation
• Automated Scanning & Code Reviews
• Avoiding Components With Known Vulnerabilities
• Sanitizing Data Inputs and Outputs

Why Is Secure Coding Important?

Secure coding requires a shift in responsibility for security, emphasizing the developer’s role in achieving code security instead of relying on the security team. This approach encourages shifting security processes left, a core best practice for securing the software development lifecycle (SDLC).

Secure coding provides a layer of abstraction, scanning existing and new code for vulnerabilities while committing it into the code repository. It enforces security best practices to ensure high-standard code in production and minimize human error, such as developers “cutting corners” to meet a deadline. 

Code Vulnerabilities and Threats 

Malicious Code

Like any other software, malicious code is implemented as instructions executed on a computer designed to achieve various purposes. For example, threat actors can design malicious code that steals sensitive information or denies access to important functionality or data.

However, malicious code can only achieve its purpose when executed. Here are common methods threat actors can use to execute malicious code on a targeted computer:

• Malicious scripts—threat actors often include executed code that can run inside a user’s web browser. Malicious scripts embedded in websites can collect sensitive information from unsuspecting users or exploit browser vulnerabilities to gain unauthorized access to the user’s computer.
• Vulnerability exploitation—software that processes untrusted user data can allow user data to be interpreted and executed as code. Remote code execution (RCE) vulnerabilities enable threat actors to execute malicious code using the access and permissions of a vulnerable application.
• Supply chain exploits—organizations often use third-party software and libraries, including them in their applications and network. Threat actors can insert malicious functionality into external code or exploit vulnerabilities in third part components to execute code on a target machine.

Code Injection

Code injection attacks occur when threat actors inject malicious code into an application, which executes or interprets the code. Successful code injections can affect the function or performance of the application. 

Code injection attacks often exploit existing vulnerabilities, like processes that handle data from an untrusted source insecurely. For example, improper validation of output and input data, such as data format, permitted characters and expected data volume. 

Buffer Overflow Attacks

A buffer overflow vulnerability typically results from improper programming. It is located in a fixed-length block of buffer or memory and occurs when a process or program tries to input more data than the buffer can hold. As a result, the buffer overflows, allowing threat actors to crash, modify, or control the affected system.

Cross-Site Scripting (XSS)

XSS is a common security vulnerability that can affect any website, including trusted ones. It occurs when threat actors inject malicious scripts into the input field of a web application. When a browser renders these scripts, it is nearly impossible to identify them as a foreign injection. 

A successful XSS attack allows threat actors uninterrupted access to end-user browsers. They can then access the sensitive information stored in the browser and manipulate the HTML of pages to access specific information.

4 Secure Coding Standards

Secure coding standards include processes, guidelines, and rules teams can use during design and development phases to prevent security vulnerabilities that may result from coding errors. These standards help teams adopt security best practices throughout the SDLC.

Here are notable secure coding standards:

OWASP Application Security Verification Standard (ASVS) 

The Open Web Application Security Project (OWASP) is a nonprofit foundation that provides resources that help develop, manage, and maintain secure software. The OWASP ASVS provides a framework for testing web applications’ technical security controls. It also offers a list of requirements to achieve secure development.

Related projects:

• OWASP Top Ten Proactive Controls (2018)
• OWASP Top Ten Risks (2021)
• OWASP Cheat Sheet Series

Common Weakness Enumeration (CWE) 

CWE is a list of hardware and software security vulnerabilities in various programming languages, such as C, C++, and Java, code libraries, and applications. The list includes the most critical vulnerabilities that can cause massive damage when exploited.

The CERT standard

The CERT standard supports frequently used programming languages like Java, C, and C++. It compiles a comprehensive list of vulnerabilities and provides a risk assessment emphasizing the consequences of failure to comply with the standard.

DISA STIG 

The DISA STIG standard offers IT and communication support to organizations or teams under the US Department of Defense (DoD) umbrella. It helps oversee institutions’ IT issues in transporting, managing, and sorting vital information. The STIG guides the functioning of institutions and directs them on how to best handle security systems.

4 Critical Secure Coding Best Practices 

1. Code Minification and Obfuscation

You can deter potential attacks by making code harder to access and read. Minifying code is a common practice for JavaScript projects, usually intended to improve performance. It involves removing white spaces and line breaks from the code to reduce the footprint of code files. However, it also makes exposed code harder to read. You can also employ code obfuscation to turn human-readable code into difficult-to-understand text.

2. Automated Scanning & Code Reviews

Attacks like cross-site scripting (XSS) and SQL injection (SQLi) can exploit security vulnerabilities in code. These vulnerabilities can result from code weaknesses that fail to distinguish between commands and data. 

XSS enables actors to execute malicious code, and SQLi attacks try to steal or manipulate data in internal data stores. You can mitigate these risks by using automated tools to scan your code for vulnerabilities and regular secure code reviews.

3. Avoiding Components With Known Vulnerabilities

Open source components and libraries are common entry points for threat actors because many include publicly known vulnerabilities and other potential exploits. You can maintain code integrity by continuously monitoring for new vulnerabilities across the SDLC and refraining from using components with known vulnerabilities.

4. Sanitizing Data Inputs and Outputs

Never trust data from external data sources or users, such as cookies, API calls, and local storage. Accepting data as-is allows threat actors to submit an input containing coded commands. Successful code injection attacks enable actors to insert malware, take control of a system, or retrieve data.

Sanitize data inputs

You can mitigate this risk by sanitizing data to ensure code commands were not provided by data inputs. Sanitizing ensures the data does not contain unexpected or invalid characters by checking all inputs against regular, authorized expressions. 

Sanitize data outputs

Additionally, you should remove system information to sanitize outgoing data. Never give away information in alerts, error messages, or URLs that actors can use to exploit your system. For example, never display API keys in URLs.

Related content: Read our guide to vulnerability scanning (coming soon)

Secure Coding with Aqua Security

Aqua provides the following capabilities which support secure coding in your organization:

• Universal Code Scanning – scan all of your organization’s source code in minutes to detect vulnerabilities, open-source license issues, infrastructure as code (IaC) misconfigurations, secrets, malware, and more. Periodic scans keep you alerted to new risks as your code changes.
• In-workflow alerts – Aqua analyzes your code and notifies you wherever the code is: as an alert in your Integrated Developer Environment (IDE), as a comment on your pull request in your Source Code Management (SCM) platform, and as an alert (or build failure notification) in your CI pipeline before release.