What Is the Secure Software Development Lifecycle (SSDLC)?

What is the Secure Software Development Lifecycle?

The Secure Software Development Lifecycle (SSDLC) is an approach to software development and delivery that emphasizes security at all relevant stages of the process.

Put another way, the SSDLC is what you get when you make security a chief priority during software development and deployment – as opposed to running security tests and scans after you’ve already built an application, or performing them only at certain stages of the development process and missing out on additional opportunities to discover security issues in your application.

In this article:

• Why is the SSDLC important?
• Creating an SSDLC framework: Secure software development lifecycle processes
• Secure SDLC phases
• SSDLC vs. SDLC
• Secure SDLC best practices
• Enhancing SDLC security with Aqua

Why is the SSDLC important?

Having a secure SDLC is important for several reasons:

#1. Security as an organizational priority

Establishing an SSDLC helps bake security into your organizational culture. It sends a signal to software developers that security is something they should prioritize at all steps of the development process, rather than something that takes place on the sidelines.

In this way, the SSDLC helps put the concept of DevSecOps – meaning close collaboration between security teams and other technical teams – into practice. It also encourages a security-first culture within the organization.

#2. Enhanced security coverage

When you run security tests and scans at multiple stages of the SDLC – including testing early, a practice known as shift-left – you maximize your chances of discovering flaws before deploying insecure code into a production environment.

This is because different types of tests can reveal different risks. For example, using a Static Application Security Testing (SAST) tool, you can scan newly written source code and discover issues like code injection vulnerabilities. Later, you can use a Source Composition Analysis (SCA) scanner to scan compiled applications and their dependencies for risks that originate from third-party code you’ve integrated into your application. SAST scanners aren’t effective at identifying these types of risks, so you’d need to perform additional testing beyond SAST at a later stage of the SDLC to ensure full security coverage.

#3. Efficient remediation of security issues

The earlier you discover a security issue during the SDLC, the easier it tends to be to fix it.

For instance, if you scan new source code and discover a problem, developers can simply rewrite the code. But if you don’t catch the issue until the code has already been integrated into the application’s main code base, compiled and deployed, fixing the issue requires the development team to update the code, and then repeat each step. They may also have to modify other code that depends on the code they updated to fix the security issue, further increasing the time and effort required to remediate the problem.

By encouraging early and frequent security tests, the SSDLC helps avoid issues like these, making security issue remediation faster and more efficient.

#4. Stronger compliance

Although no major regulatory framework includes specific rules related to security within the Software Development Lifecycle, a secure SDLC can help demonstrate to regulators and auditors that your organization prioritizes security and has adequate security controls in place – which is something that some regulations require.

So, while it wouldn’t be quite accurate to say that the SSDLC is a strict compliance requirement, it does help meet compliance mandates.

Creating an SSDLC framework: Secure software development lifecycle processes

Because every organization’s software development and deployment processes are different, approaches to implementing an SSDLC will vary.

In general, however, establishing a secure SDLC starts with creating an SSDLC framework that identifies the following:

• Which security policies and best practices developers should follow when designing and implementing applications.
• Which types of security tests or scans the organization performs during the development process.
• When those tests and scans take place during the SDLC.
• How developers react to tests and scan results. For example, which types of security risks mean that the application development process needs to pause until developers fix the issues?
• How developers, IT operations engineers, and security experts communicate and collaborate to ensure everyone has visibility into the state of the SSDLC.

For best practices on how to define secure software development lifecycle processes, OWASP SAMM, an open framework to help businesses manage cybersecurity risks, is helpful. In particular, consider the guidance in the SAMM Implementation Model, which covers software development and deployment processes.

NIST SSDF (which is based in part on OWASP guidance) is also relevant, especially for examples of implementation of secure processes at various stages of the SDLC.

Secure SDLC phases

Once you have an SSDLC framework, you can use it to drive the integration of security into all relevant stages of the SDLC. Again, the exact process will vary from one organization to the next, but key phases of the SSDLC typically include:

• Planning: During the planning stage, which involves defining the overall goals and structure of a software project, developers should ensure that security is a priority and that adequate resources are available within the project to support it.
• Design: When developers design an application, they should assess potential security risks and ensure that the design mitigates them.
• Coding: As they write code, developers should adhere to best practices for secure coding. They should also consider running security tests on newly written code as a way of catching some security issues early.
• Testing: The testing phase of the SDLC typically happens after all new code has been written and compiled and the application is deployed in a dev/testing environment. This is another opportunity to perform tests, even if earlier testing of source code already happened.
• Maintenance: Once the SDLC reaches the maintenance stage, meaning that the application has been deployed, security testing and monitoring should continue to discover risks that may not have been evident from testing in a dev/test environment.

SSDLC vs. SDLC

When implemented properly, an SSDLC includes several key features that don’t factor into a standard SDLC. The following table illustrates key differences between SSDLC and SDLC.

Secure SDLC best practices

Declaring security a priority and integrating security across all key stages of the SDLC is a start. But to get the very most from the SSDLC concept, consider the following best practices:

• Define clear security policies and procedures: Policies and procedures serve as the foundation that everyone in the organization can refer to when deciding exactly which types of security practices and tests to implement during the SDLC.
• Delegate responsibilities: To ensure that engineers will actually react quickly to issues identified during security testing, make clear who is responsible for doing what. Otherwise, you risk finding security problems that no one actually fixes because they think it’s someone else’s job.
• Automate security testing: Automating tests and scans is critical for ensuring that the secure SDLC keeps moving efficiently, and that testing doesn’t delay application releases.
• Set priority levels: Not every security issue is necessarily serious enough to merit delaying application delivery until the issue is fixed. For example, you might discover a vulnerability that is not actually exploitable in the application’s deployment environment. By assigning priority levels to vulnerabilities, it becomes possible to establish guidelines for how the team should react.

Enhancing SDLC security with Aqua

As an application security platform that covers code-to-cloud, Aqua provides the security testing, scanning, and collaboration features teams need to make security a priority across stages of the SDLC.
Request a demo to learn more about how Aqua can help your organization put the principles behind SSDLC into practice.