SAST Fundamentals for Securing Source Code

Developers use SAST (Static Application Security Testing) to safeguard code before deployment, making for better coding practices from the start. But using SAST fundamentals for securing source code isn’t a perfect solution, and apart from building team buy-in and expertise, leaders will find they’re contending with secondary challenges as well: compliance requirements, depth of coverage, overlap with existing tools, and open-source dependencies all complicate the seemingly simple idea that greater security comes from testing code early. We’re breaking it down.

What is SAST?

SAST is a tool — a software product — that checks an application’s source code for vulnerabilities before new apps are ever run. SAST involves scanning code early in the software development lifecycle and represents a “shift left’ approach that attempts to catch issues before vulnerabilities turn into breaches when they’re easier and faster to remediate.

Core features of SAST include:

• Code-Level Analysis: SAST examines code for common issues like SQL injection, cross-site scripting, buffer overflows, and hardcoded credentials.
• Early Detection: SAST allows for problematic code to be identified without executing the code. Because the development process is still underway, vulnerabilities are simpler to fix and don’t disrupt users.
• Testing without Running an Application: SAST differs from Dynamic Application Security Testing (DAST), in which code must be executed to be tested. That’s the “static” scanning component of SAST.
• Automation: SAST can be integrated into the CI/CD pipeline to automatically scan new code and make alterations. This makes testing and remediation easier for developers.
• Multi-Language Support: SAST tools can function across programming languages, from Java to Python and C++.

There are paid and open-source SAST solutions. Open-source tools like FindBugs (for Java) and Brakeman (for Ruby on Rails) may require more setup and customization compared to their commercial counterparts. 

Benefits of SAST Tools

Building software with compromised parts can lead to larger cracks that impact the entire structure of an application. When deployed, fixes may mean downtime, loss of customer loyalty, and more expensive fixes on multiple parts of an app. On the other hand, a single fix on a single component upfront can obviate these issues. The promise of pre-deployment code scanning is attractive.

Threats are growing. There were 30,000 new vulnerabilities identified last year alone (a 17% increase over the previous year). 

Developers can’t be expected to keep up with or memorize the issues. And updating code by hand presents its own set of complications, grinding development time to a halt. 

SAST tools promise to help tame the problem of vulnerabilities in deployed code, but they don’t do it by including runtime insights, so their view is always a partial one. In spite of the limitations, SAST adds to coding security, providing teams with these benefits:

Early Detection of Vulnerabilities

Early scanning helps identify issues while the code is still being written and when it can be remedied with a few keystrokes. Catching these vulnerabilities early reduces the cost and complexity of fixing them later in the lifecycle, especially after deployment.

Comprehensive Code Coverage

SAST tools can analyze the entire source code, including complex logic paths and business rules. While dynamic testing tools focus on specific runtime scenarios, SAST offers a broad static analysis that can catch vulnerabilities across the entire codebase, including those in libraries and dependencies.

Integration into the CI/CD Pipeline

SAST tools can be integrated directly into the CI/CD pipeline for continuous, automated security testing as part of the development process. That speeds the development process and helps prioritize security as an ongoing consideration as developers push code.

Limitations of SAST Tools

SAST evolved in the late 1990s alongside DAST, as both sought to protect the growing world of web applications, increasingly the targets of cybersecurity threats. While SAST was improved with integrations into the CI/CD lifecycle to be more efficient over the years, scanning every bit of code before it ever runs is often critiqued as inefficient in and of itself. Here are key drawbacks to the approach:

False Positives

SAST tools can often generate false positives. Because there are so many vulnerabilities, SAST tools can flag a good deal of code as insecure, quickly drowning development teams in suggestions for code revisions. Some tools use filters to prioritize code, but those filters will never incorporate runtime insights since SAST specifically tests code without running it. The result? Developers may spend time investigating or fixing non-issues, slowing down the development process and potentially leading to missed real vulnerabilities.

Lack of Runtime Testing

SAST focuses exclusively on static code analysis and cannot detect vulnerabilities that only appear during runtime. It won’t catch anomalies in an application’s behavior or configuration flaws and vulnerabilities that emerge in interactions between systems. Dynamic testing tools (DAST) or runtime security tools with CI/CD pipeline integration are needed to fill this gap. SAST can’t detect all kinds of vulnerabilities on its own.

Complexity in Large Codebases

For larger or more complex apps, SAST can become resource-intensive and time-consuming. Scanning large codebases with many dependencies or microservices can slow down the CI/CD pipeline. And SAST tools may not understand intricate or proprietary code patterns, so time spent may not lead to the comprehensive identification of vulnerabilities.

Lack of runtime insights and false positives go hand in hand: without visibility into runtime anomalies and vulnerabilities, SAST will always require additional tools for a complete solution. 

SAST vs DAST (vs Other Solutions at a Glance)

App security spans multiple layers, from code security, where SAST and software composition analysis (SCA) shine, to runtime security, cloud and container security, and identity and access security. Because each of these layers comes with distinct threats and differing attack surfaces, no single “complete” solution does it all. 

SAST and DAST are 2 of the most widely known solutions, but they have their own strengths and weaknesses, and further, other solutions like runtime CNAPP and Interactive Application Security Testing (IAST), which runs inside the app and is useful in CI/CD pipeline environments, become relevant for teams depending on their security needs. 

Here’s a comparison of features:

Feature	SAST	DAST	IAST	Runtime-Powered CNAPP
Static Code Analysis	Yes	No	No	No
Dynamic Behavior Testing	No	Yes	Yes	Yes
Security During Runtime	No	Yes	Yes	Yes
Detects Misconfigurations	No	Yes	Yes	Yes
Focuses on Code Vulnerabilities	Yes	No	Yes	No
Focuses on Live Application Behavior	No	Yes	Yes	Yes
Real-Time Threat Detection	No	Yes	Yes	Yes
Integrated into CI/CD	Yes	Yes	Yes	Yes
Automation Support	Yes	Yes	Yes	Yes
Comprehensive Cloud-Native Security	No	No	No	Yes
Scans Dependencies (e.g., open-source)	Yes	No	Yes	Yes

Tool sprawl aside, combining SAST, DAST, and runtime CNAPP (or even IAST) provides a more comprehensive security posture by covering different aspects of an application’s lifecycle. Here are the most efficient combinations based on use case:

• SAST + DAST:
  Combining SAST and DAST is a strong combination for protecting both code security and runtime security. It’s best for application security when teams want both static code analysis and real-world attack scenarios.

SAST catches vulnerabilities early in the development phase, while DAST allows teams to test how the app behaves in the real world. The combo means fewer of SAST’s false positives, while addressing the code itself — which DAST alone can’t accomplish. It’s a manual way of finding which vulnerabilities that can be attacked and prioritizing them faster.

• SAST + Runtime CNAPP:
  For addressing both application code and cloud-native infrastructure, combining SAST with a runtime CNAPP provides code-level vulnerability detection. At the same time, it will also monitor cloud-native environments (e.g., Kubernetes, containers, misconfigurations, and runtime threats). 

This combo ensures comprehensive coverage for modern applications, especially in dynamic cloud environments. Using SAST ensures clean code, while the CNAPP prevents deploying containers with known vulnerabilities. Issues like exposed credentials can be removed before an attacker can exploit them.

• Runtime CNAPP + DAST:
  Organizations heavily invested in cloud-native applications and looking for real-time monitoring, using runtime CNAPP in combination with DAST can be a strategic move. 

DAST manages apps’ dynamic security, while runtime CNAPPs make sure there’s ongoing protection in the cloud. In other words, DAST validates that flaws exist, and CNAPP prevents exploits spreading throughout the cloud environment.

The Future of SAST

There’s still a place for SAST. It’s especially valued in highly regulated industries like finance and healthcare, where secure coding practices are table stakes. However, the role of SAST is evolving given the rise of IAST, RASP, and CNAPPs to meet the call for more runtime visibility. Today, hybrid approaches help secure both coding practices alongside runtime, for a combined shift left and shift right strategy.

As application security needs continue to evolve and cloud computing replaces legacy systems across organizations, SAST will likely become more sophisticated, keeping up with more and more vulnerabilities and emerging threats. 

What will that future look like? We have some ideas.

1. AI-Driven Vulnerability Prediction: Already, advanced runtime CNAPPs and SAST tools use machine learning to reduce false positives and speed up analysis. Expect strides in pattern recognition, flagging issues even before they appear in the development process. 
2. Real-Time Vulnerability Patching: Today, some SAST tools can automatically suggest or apply fixes as developers write code. But so far, this capability is limited. Expect a future where reliable “coding assistants” can address vulnerabilities as developers code.
3. Automated Ethical Hacking Integration: Today, SAST tools can’t adjust coding scans based on live attack simulations, but expect this upgrade in the future. More dynamic and adaptive coding tools based on growing available data on attacks is already on the way.
4. Cross-Layer Security Analysis: Future SAST tools may expand to scan not only the code but also dependencies and configurations in a single scan, whereas currently, tools can’t cover the entire stack.
5. Quantum-Resistant Security: With the rise of quantum computing, SAST tools must evolve to check code for vulnerabilities that may be susceptible to quantum-powered attacks.
6. Behavior-Driven Static Analysis: Combining SAST with runtime behavior simulation, future tools could predict vulnerabilities based on both code and its expected interactions with other services, offering deeper insights without executing the code.

As SAST adapts, one thing’s for sure: it will have to integrate more data, approaches, and types of attacks to stay relevant.

Upwind Brings Runtime Insight to the CI/CD Pipeline

For now, comprehensive CNAPPs can give teams a glimpse of tomorrow’s comprehensive security. CNAPPs like Upwind use runtime insights right in the CI/CD pipeline to avoid the false positives of SAST and make sure only critical vulnerabilities take up developers’ time. With prioritized data injected straight into the build process, better apps — earlier in the process — are simpler.

To see what runtime-powered insights can bring to your builds, schedule a demo.

FAQ

When can static application security testing be used?

SAST can be used early in the software development lifecycle (SDLC) to find flaws in source code, bytecode, or binaries. It can be used in the CI/CD pipeline for compliance audits before deployment, like PCI-DSS, OWASP Top 10, or NIST, or for legacy codebases without running them.

When should teams not use SAST? It won’t work for detecting real-world runtime vulnerabilities, business logic flaws, or securing cloud workloads and infrastructure. Teams will need DAST, IAST, and CNAPP to manage those tasks. 

What is the difference between source code analysis and SAST?

SAST is a particular type of code testing that’s part of the broader category of source code analysis. Source code analysis includes any testing or process that checks code quality and security. While it may include checks for security flaws like misconfigurations and hardcoded secrets, it doesn’t always have to. Source code analysis could look for other types of inefficiencies that improve code performance once deployed.

Can SAST be integrated into CI/CD pipelines?

Yes, SAST is often integrated into the CI/CD pipeline so it can catch security issues before deployment with minimal speed bumps during development. Automated scans run in development tools, where developers get instant feedback as they write code. SAST can block builds if high-risk vulnerabilities are detected. 

Integrating SAST into the pipeline isn’t friction-free, however. Slow scans may delay builds, false positives may bog down development, and developers may need machine learning to identify only critical issues, along with automated fixes to keep development moving.

Can SAST tools detect all security vulnerabilities?

No, SAST tools aren’t standalone solutions. They miss issues related to:

• Runtime behavior: SAST will not detect in-memory attacks or API abuse.
• Business logic: SAST won’t identify logic errors in workflow-based attacks.
• Infrastructure misconfigurations: SAST won’t check cloud misconfigurations or network security issues.

SAST tools detect: 

• Code injection: From SQL to XSS and command injection, SAST will identify insecure input handling.
• Hardcoded secrets: SAST can identify API keys, passwords, and sensitive credentials.
• Insecure coding patterns: SAST will flag improper authentication, cryptography misuse, and memory leaks.