Code security auditing 101

In modern software development, code security analysis is a crucial part of the “prevention-is-better-than-cure” paradigm. Code security auditing improves code quality and is thus a good DevSecOps practice for any organization.

Setting up a code security audit tool is generally the responsibility of the DevOps and — if it exists within the organization — DevSecOps teams. In addition, because static code analysis directly scans source code, it is useful to have at least one developer involved to provide insights about possible vulnerabilities.

Types of code security audits

The two most frequent types of audits are static and dynamic code auditing.

Static code auditing, also known as static code analysis or simply referred to as a scan, is the examination of the source files in order to discover vulnerabilities. In other words, it is an automated code review that can focus on a number of different aspects such as code standards, code formatting, or code vulnerability.

The most popular type of code security audit in the industry is static analysis centered on code vulnerability. This will be the main focus of this article. Find out more about the different security audit types here.

Why is code auditing important?

Neglecting to perform code security analysis puts you at risk. Scanning code for vulnerabilities is generally considered the most important function of static analysis because it helps to prevent cyberattacks against your deployed software in the long term. With a reliable pipeline in place scanning your sources, vulnerabilities can be found, allowing you to take immediate action and thus limiting the time window for an attack.

Legal and compliance issues must also be addressed as risks, as discussed below.

In the open-source context, static code analysis, including open-source static code analysis and open-source audit are also considered best practices.

What to check during code security auditing

Code security auditing should be customized for the user codebase, but there are several common vulnerabilities that can be a good starting point:

1. Input validation/SQL injection

2. Third-party libraries

3. Hardcoded Credentials

4. Weak cryptography

5. SSL/TLS version

6. Memory overflow

7. Compliance

8. Licensing

9. Project specific checks

Let's dive into each of these in more detail:

1. Input validation/SQL injection

SQL injection is one of the most popular cyberattack techniques. It uses an SQL query to trick your application into performing a malicious SQL transaction. A common approach is to inject SQL code into web page input, which can, for example, allow attackers to gain access to unauthorized data or to delete data. Static code analysis helps prevent such attacks by identifying places where SQL could be injected.

2. Third-party libraries

Third-party libraries are a critical part of modern software development. Developers can reuse code made and tested by others, thus improving team efficiency and allowing for greater focus on core business goals.

The downside of third-party libraries is that they are susceptible to vulnerabilities. But these risks can be mitigated by using source code analysis to run daily checks on all your libraries.

3. Hardcoded credentials

In general, hardcoded API keys and passwords are strictly forbidden in source code. However, when locally testing a new feature or integration, people sometimes forget to remove hardcoded credentials.

In the unlikely event that a hardcoded value goes undetected during the code review—perhaps in a very large merge/pull request—a static code analysis tool should find it and warn you about it.

4. Weak cryptography

Some cryptography algorithms are not secure and should be prohibited for secure applications, even if they have been widely adopted for older applications. An example is the MD5 Hash algorithm, which should be avoided; instead, the more secure SHA-256 can be used, depending on the application.

5. SSL/TLS version

SSL/TLS encryption, the latest version being TLS 1.3, is an essential method in internet security. For example, if your codebase runs an HTTP server with a deprecated version of TLS/SSL — or worse, legacy code runs a web server on a non-private network without TLS/SSL — static code analysis can find it and warn you about it.

6. Memory overflow

Memory overflow occurs when a memory buffer overruns the set boundary. It can then overwrite the next memory location. The issue is more common in languages like C and C++ which allow you to manipulate memory more easily.

With proper secure code analysis, memory overflow can often be detected in source code, thus preventing dangerous runtime behavior. For embedded, industrial, high-speed developers, this is a must.

7. Compliance

Some industries require standard compliance such as ISO. For example, ISO 270001 and ISO 26262 outline specific requirements that must be met for software to be certified. Static code analysis can also help verify other compliances, such as SOC for customer data management and PCI for payment industry applications. Static code analysis allows you to check your current code for compliance and ensure that any newly introduced code is compliant.

8. Licensing

Most modern software projects rely on external software libraries. Code reusability is a major advantage for software developers. Most external libraries (module or frameworks, for example) come with licensing information (MIT, GPL, BSD, and more).

Some licenses are completely free of charge, even for commercial use, while others require payment. By parsing your dependencies, static code analysis can confirm that you are complying with the licensing of your external libraries. This reduces the possibility of legal action against your organization.

9. Other

Code security audits are capable of checking many more elements, including code standard compliance and code formatting. A security auditing tool can automate part of the code review, which is a good practice for secure code review. What’s most important is that your code security audit scans for the type of vulnerabilities that can impact your organization the most and are most likely to be present.

For instance, if you’re working on an embedded system codebase in C with no database connection to it, SQL injection would be less of a concern; checking for memory overflow, however, would be crucial.

What tools can be used to perform a code security audit?

There are a number of available testing tools that can be used for code security auditing, including:

• Static application security testing (SAST): Parses source code to find issues.

• Dynamic application security testing (DAST): Runs your application and evaluates your application security using techniques such as application penetration testing.

• Software Composition Analysis (SCA): Looks for vulnerabilities in open-source direct and indirect dependencies.

Automated scans and reporting

Incorporating code scans into your CI/CD pipelines (such as Github Actions, GitLab, or Jenkins) is a recommended best practice. Automatically running scans can be done with most modern CI/CD tools and is far more efficient than manual scans. Automated scans save time and effort, running only when needed and preventing issues caused by human error.

Depending on your situation, running a scan on every pull/merge request is an effective way to prevent vulnerabilities in your codebase. Having a cron job that runs the analysis every 24 hours is also recommended since new vulnerabilities are constantly being added to the remote database.

The faster your team is notified of an issue in your codebase, the faster you can work to fix it and avoid other threats. To ensure rapid response time to vulnerabilities found in your source code, it’s important to set alerts for when issues are identified. Integrating an alert mechanism into your CI/CD is easy. These notifications can be as simple as an email noting that your static analysis pipeline has failed.

Choosing a code security auditing tool

When choosing a static analysis tool or security audit software, there are a few criteria to consider:

• Programming language: Select a tool that supports the programming language used in your codebase. Some static analysis tools work with multiple languages, allowing for a single tool to fit all your codebases.

• Core features: An essential consideration for selecting the right tool is that it addresses the risks that matter to your organization and codebase. Depending on your industry and requirements, you might not need a tool that checks for ISO compliance; or memory overflow may not be relevant to your setup and programming language.

• CI/CD integration: Most tools can be easily integrated into CI/CD, which is important for automating the scanning process.

• IDE integration: IDE-integrated tools make it easy to run scans directly on the developer IDE with the click of a button. You can even configure scans to run before a commit.

Getting started with code security auditing

Source code analysis is an important part of secure coding practices, and combined with cybersecurity audits, it should be an integral part of any cyber risk management program.

Compatible with multiple modern programming languages such as Javascript, Go, and more, Snyk Code finds vulnerabilities directly in your code. Snyk Open Source analyzes and automatically detects vulnerabilities in project dependencies.

Be ready for the next Log4j. Secure your codebase and prevent security threats with Snyk developer-first tools. Sign up for free or book a demo. Try our free online code checker tool to see how the Snyk code engine analyses your code for security and quality issues.