Differences Between Static Code Analysis and Dynamic Testing

With reports of data breaches and website vulnerabilities on the rise, securing the Software Development Life Cycle (SDLC) has become one of the top priorities of enterprises all around the world.

Software testing is a critical part of the software development journey. It determines the quality and performance of an application and identifies potential vulnerabilities in the code.

The most popular forms of security testing include static code analysis and dynamic testing. While both security testing methods help identify vulnerabilities in applications, they both have their own purpose, tools, and processes.

Let’s take a look at both methods to better understand the differences between static code analysis and dynamic testing.

Static Code Analysis

Static code analysis, or simply Static Analysis, is an application testing method in which an application’s source code is examined to detect potential security vulnerabilities. It is usually accomplished by testing the code against a set of standards and best practices that identify vulnerabilities within the application.

What Does it Cover?

A static code analysis often addresses code vulnerabilities and other code weaknesses. It often uses data tracing tools that find many vulnerabilities that often escape most human eyes.

Static Code Analysis Techniques

• Automated tools- Static code analysis involves many automated tools that help detect potential vulnerabilities in the source code.

  • Simple grep searches- Grep is a search utility that allows you to search for specific terms. Grep style searches can help discover information related to encryption, cryptography, SQL queries, URLs and sockets, and file read and writes. While powerful, these simple grep searches can lead to many false positives.
  • Tools with data flow analysis- Automated tools like PumaScan, Fortify and Checkmarx actually trace data through the application and so it can detect when untrusted data is used in a trusted manner, e.g., when untrusted user input is sent to the browser unencoded (XSS vulnerability) or inserted directly into a SQL query (SQL Injection).  This data flow analysis capability is essential for any serious assessment of the security of an application.
• Static Code Review - A static code review is also known as white-box testing. It includes checking the overall security of the application to identify potential vulnerabilities and risks associated with it.

Where in the SDLC can we use Static Code Analysis?

Static code analysis should be performed at all stages of the SDLC once the development phase has begun. It should be incorporated into the SDLC before the unit/component/integration testing phases begin.

In most cases, the static code analysis results are incorporated as a quality check for code promotion in continuous integration (CI) and continuous delivery (CD) pipelines.

Benefits

Static code analysis has plenty of benefits, and its ability to quickly discover weaknesses in the code and to comply with security standards helps reduce potential vulnerabilities.

What are some of the key benefits of using static code analysis?

• Early detection of code vulnerabilities reduces the cost of debugging and fixing at a later stage in the SDLC.
• It is conducted by trained security engineers who have strong knowledge about secure coding practices.
• It is a highly scalable method which means it can run on multiple code bases and can be run repeatedly.
• It is a fast and efficient way to identify vulnerabilities in the code such as SQL Injection, buffer overflow, etc.
• Automated tools can scan the entire application source code with minimal effort.
• The use of automated tools helps provide mitigation recommendations, thereby reducing research time.

Limitations

Despite its benefits, static code analysis has a few limitations that can impact your software development lifecycle process.

One of the major limitations of static code analysis is that the use of automation tools often gives a false assurance that everything is being validated. Often there are a large number of business rules, standards, and expectations involved that automated tools are not very efficient at analyzing in a code.

What are some of the key limitations of static code analysis?

• It requires a large amount of time if done manually.
• Automated tools often work with only a few programming languages.
• Automated tools will provide false negatives and many false positives.
• Automated tools can not scan the source code for compliance with business goals.
• Security vulnerabilities like authentication problems, insecure use of cryptography, access control issues, etc. are very difficult to find automatically.

Dynamic Testing

Dynamic testing is the method of debugging an application’s source code in a run-time environment, i.e when the application is running. It is used to identify security vulnerabilities while the program is running.

Since the program can be run with multiple inputs, the scope of a dynamic assessment can get quite large.

What Does it Cover?

Dynamic testing can help discover a wide range of vulnerabilities such as input/output validation issues that could expose security vulnerabilities and make it vulnerable to SQL Injection (SQLi), Cross-Site Scripting (XSS), etc.

In addition to this, dynamic testing also helps identify security misconfiguration and other common issues that might impact the overall security of the application.

Automated dynamic testing allows users to continually scan applications as they evolve and facilitates the automatic detection of vulnerabilities. Automated alerts can be set in these tools that will send alerts and notifications once a vulnerability is detected.

Dynamic testing also includes manual test cases to detect vulnerabilities that are otherwise not easily discovered by automated tools such as session management issues, information leakage, authentication issues, access control, and more.

Where in the SDLC can We use Dynamic Testing?

Dynamic testing can be incorporated during multiple stages. In the pre-production stage, dynamic testing prevents error-prone code from going into the production phase. This can be used as a quality test with continuous integration (CI)/continuous delivery (CD) tools for code promotion. During the production stage, dynamic testing can help troubleshoot production issues quickly.

Benefits

Dynamic testing is a great method to identify vulnerabilities in a run-time environment. It helps identify issues in the application which thereby reduces the time to identify production issues.

What are some of the key benefits of using dynamic testing?

• Identifies vulnerabilities in a run-time environment.
• Automated tools offer flexibility on what to scan for.
• Helps identify vulnerabilities that might not adhere to business context or standards.
• Permits you to validate the findings from static code analysis.
• Allows for the testing of the application without having access to the source code.
• Can be applied to any application.

Limitations

Although dynamic testing helps validate the reports by static code analysis, which gives a better security assurance, there are still some limitations to dynamic testing.

What are some of the key limitations of dynamic testing?

• Automated tools may produce false negatives and false positives.
• There is a lack of trained professionals who can thoroughly conduct dynamic testing.

Takeaways

Static code analysis identifies issues in code, whereas dynamic testing uncovers issues in running applications that static analysis may not cover. Both of these testing methods go hand-in-hand. How and when you implement these testing methods in your SDLC depends on your requirements.