Shift-Left Security: What It Means, Why It Matters, and Best Practices

What Is shift-left security?

Shift-left security is the practice of beginning security tests as early as possible in the software development lifecycle (SDLC). It’s called shift-left because it involves moving testing “to the left,” if you think of the SDLC as a set of processes that, when visualized on a piece of paper or screen, move from left to right.

“Early” is a relative term, of course, and there are no hard-and-fast rules about exactly how early you need to start security tests to shift security left. But in general, the premise behind shift-left security is that as soon as you can begin testing, you should. In practice, this typically means scanning newly written source code to detect problems like code injection and arbitrary code execution risks.

Importantly, shifting security left doesn’t mean that you only perform security testing early in the SDLC. Security tests and monitoring should continue through later stages of the development process. The idea behind shifting left is simply to start testing earlier than teams traditionally did.

Why does shift-left security matter in DevSecOps?

Shifting security left is important for two main reasons in the context of DevOps and DevSecOps.

Enhanced security coverage

By increasing the number of tests you perform, shift-left security increases your chances of uncovering risks and vulnerabilities before they are exploited – leading to a reduced risk posture. This is especially true because tests run at different stages of the SDLC often reveal different vulnerabilities – so if you only tested once, you might not catch all issues.

Faster, simpler remediation

The earlier you detect a security risk, the less time and effort it typically takes to fix it. This is mainly because correcting an issue in code that you just wrote usually requires you to fix only that code. If you don’t discover the issue until a later point in the SDLC, you might have other code that depends on the insecure code, requiring you to overhaul a substantial part of your codebase to fix the problem. Plus, you may need to recompile your entire application again, further slowing down the remediation process.

In this respect, shift-left security can help enable DevSecOps (meaning seamless integration of security into the development process) by reducing friction between developers and security teams. If developers need to rewrite large parts of an application to fix security issues, or if security flaws delay the release schedules that developers are pressured to meet, the business is likely to end up with friction between developers and security analysts. It’s also possible that developers will simply ignore security directives, or ship code that they know is insecure, because they feel so much pressure to meet tight release deadlines.

By finding security issues early-on using shift-left security, this friction can be avoided because developers can fix the problems with minimal effort and minimal delay to software release schedules.

Shift-left vs. shift-right security

As we noted above, shifting security left doesn’t mean that you only test early in the SDLC. Testing later is also important – so important, in fact, that teams often emphasize the concept of shift-right security, which means extending security testing into production environments, as opposed to testing only prior to deploying an app into production.

In this sense, you can think of shift-left and shift-right security as different sides of the same coin. Used together, they improve overall application security. But if you only perform one type of testing – if you only test early-on and ignore the importance of monitoring and testing in production environments, or if you wait until an app is in production to perform security tests – you’re unlikely to uncover all risks before threat actors exploit them.

5 benefits of shifting left

Shifting security left offers several key benefits from both a technical and business perspective:

1. Fewer breaches: By increasing teams’ ability to detect and fix issues fast, shift-left security can help reduce the overall breach rate.
2. Fewer delays: The earlier you detect security risks, the easier it is to fix them without having to delay releases. In this sense, shift-left translates to faster time-to-market.
3. Happier developers: As noted above, developers benefit from shift-left because it allows them to fix issues with less effort.
4. Happier security teams: Security teams, too, benefit from shift-left because it allows them to advance their priorities – which center on security – with minimum pushback from other teams.
5. Reduced costs: When developers and security teams can work together to find and fix security issues efficiently, the business benefits due to reduced costs associated with managing security risks.

Shift-left security tools

You don’t need any special tools to shift security left. But you do need a comprehensive set of security scanning capabilities, including the following:

• Static Application Security Testing (SAST) tools, which can be used to scan source code for risks.
• Dynamic Application Security Testing (DAST) tools, which can be helpful for testing applications later in the SDLC, after the apps are running in dev/test environments.
• Software Composition Analysis (SCA) tools, which can find insecure dependencies and modules inside applications, adding another layer of security.
• Security monitoring tools, which monitor production environments for anomalous behavior and other signs of attack.

To use these tools effectively as part of a shift-left strategy, teams deploy the right tools at the right stages of the SDLC. The details can vary, but in general, the first tests start with SAST scans, followed later by DAST and SCA scans. Then, once an app is in production, monitoring tools can continue the security validation process.

Note, by the way, that this is not a comprehensive list. Depending on the type of app you are building and how you deploy it, you might employ additional testing tools as part of your shift-left strategy. For example, API testing tools can help identify API vulnerabilities, while IaC scanners could detect insecure configurations in IaC code.

Best practices for shifting security left

To get the most out of shift-left security, consider the following best practices.

Develop clear policies

Instead of simply giving teams a mandate to “test early,” establish specific rules about exactly how and when security tests will occur.

Prioritize risks

The more tests you run, the more alerts you’ll get, and not all risks necessarily require remediation. To ensure that the development process isn’t bogged down as teams chase unimportant vulnerabilities, set priority levels for vulnerabilities and determine ahead of time which types of risks your teams are allowed to ignore.

Establish clear responsibilities

Decide ahead of time who is responsible for fixing issues that shift-left testing reveals. Will you expect developers to remediate problems on their own, or will your security engineers participate in the process as well. Either approach is viable, but the important thing is to ensure that roles and responsibilities are clear so that you avoid situations where everyone expects someone else to fix the problems.

Leverage remediation guidance

Detecting risks is one thing. Figuring out how to fix them is another. To ensure that developers can remediate problems as quickly as possible, consider leveraging features like AI-guided remediation, which generates recommended fixes.

Aqua’s approach to shift left

As a comprehensive application security platform, Aqua provides the broad range of security testing and scanning features that teams need to shift security left – and, for that matter, right. In addition, Aqua’s automation and DevSecOps capabilities help to minimize friction between development and security teams across all stages of the SDLC, allowing all stakeholders to work effectively toward the shared goal of reducing risk while maximizing efficiency.

Learn more by scheduling a demo.