Everything you need to know about SAST VS DAST

Static Application Security Testing

Static application security testing and dynamic application security testing; often referred to as SAST and DAST, are both different types of appsec solutions that deliver security testing and robust application security testing solutions. This article will go over everything you need to know regarding DAST and SAST security testing.

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Is DAST or SAST the right application security testing tool?

If you’re trying to detect potential vulnerabilities in your software, you may have heard of static application security testing and dynamic application security testing; but which is best, SAST or DAST?

What exactly is Dynamic Application Security Testing? 

DAST is a process that is performed from an external viewpoint, looking inwards at an application. It is typically carried out when the application is running, and it uses a myriad of techniques with the objective of penetrating the application and exposing any potential vulnerabilities. Dynamic application security testing will also look at any third-party interfaces to test and verify the security at the external entry points as well.

DAST tools are usually cheaper than SAST tools and they are considerably easier to use.

The core benefits that DAST Tools offer are:                             

  1. Provide an integral insight into any potential vulnerabilities
  2. Ideal for use prior to an application going live
  3. Where the source code is not yet available for testing

Unlike SAST, DAST tools do have trouble following specific coding guidelines and will not be able to pinpoint the precise location of the weakness.

What is Static Application Security Testing?

Another term for static application security testing is white box testing. SAST tools are used earlier in the software development process than DAST tools. Unlike dynamic application security testing, there is no requirement to have a running system before undertaking the security evaluation process.

The vast majority of all SAST tools will perform a comprehensive range of appsec solution tests which involve testing the byte code, the source code, and/or line-by-line of the binaries in order to draw out any potential vulnerabilities in the software prior to publication.

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The core benefits that SAST Tools offer are:

  1. Provide an integral insight into any potential high-risk vulnerabilities with comprehensive threat assessments
  2. Ideal for use during the developmental stages of a software project
  3. Quicker and more frequent capacity for appsec testing compared with manual processes

SAST tools are primarily for use during the developmental stages of a software project, they are more expensive than dynamic application security testing tools, and they are notoriously more challenging to use. Static Application Security tools can find key vulnerabilities during the development phase which can result in significant time and cost savings.

What are the differences between white box and black box testing?

Black Box Testing Explained

Black Box Testing is a particular method of dynamic application software testing which undertakes appsec testing without any knowledge or information regarding the code of a program.

Black box testing can be undertaken by testers who hold no programming or implementation knowledge. It reviews the secure and correct functional testing of an application while it is essentially ready to use.

White Box Testing Explained

White Box Testing is a method of static application software testing where the internal structure of the app is known to the tester, who will typically be a software developer.

Both programming and implementation software knowledge are needed to undertake this type of appsec testing. The majority of the focus is on the internal structure and the code of the app, to verify the performance of the system overall.

What is the best method for application security testing?

As you will already appreciate, both SAST Vs. DAST bring their own benefits and are designed to be performed at different stages in the lifetime of the app. A combined approach to appsec testing tools can provide significant risk mitigation advantages.

Both Static Application Security Tools and Dynamic Application Security Tools have pros and cons, with SAST being carried out earlier in the software development process, and DAST tools being used later on when combined, they serve to complement one another and provide comprehensive appsec testing features.

HAST Definition

Hybrid Application Security Testing or Hybrid Analysis is the official terminology applied to the combination of DAST and SAST. In the appsec world, there are many professionals that carry out penetration testing who are leveraging this approach at present.

One of the difficulties faced when using multiple tools is that each DAST tool and SAST tool will each report using slightly different metrics and ratings, and this can make the combination and comparison of data a little challenging.

What Types of Vulnerabilities Do SAST and DAST Expose?

There are many types of defects that can lead to appsec vulnerabilities. Some examples are listed below:

  1. SQL Injection – External bodies are able to embed DQL commands with user-provided parameters.
  2. Race Conditions – This is essentially a weak synchronization amongst a multitude of threads that could result in a program being unable to terminate indefinitely or for it to never return to a state of control.
  3. Integer Overflows – This is the utilization of insecure integer operations.
  4. Input Validation Defects – These are appsec issues that are typically caused by parameter input issues and trusted user ID problems; both of which can lead to appsec
  5. Buffer Overflows – This is general developer failure whereby they do not correctly specify the bounds for the pointer and array references.
  6. Stack Overflows – Appsec vulnerabilities with code that are a result of mistakes with the use of data buffers.

“Approximately 80% of attacks are directly targeted at the application layer” – Gartner 2018

SAST, DAST, and The Software Development Life Cycle (SDLC)

Whichever sector you operate within or whatever the purpose of your app, the ultimate goal is to ensure a secure web and mobile application development process. The development of an SDLC is one of the most effective ways to attain that goal.

Some of the world’s leading application development companies are posing a major security challenge because of the distinctive patterns that are completely different in nature. In most organizations, there will often be several of these patterns being utilized in tandem.

  • The Sequential Design Process – Waterfall
  • CIDC – Continuous Integration Continuous Development
  • Iterative Development – Agile/DevOps

DAST Tools are suited to Waterfall environments, but due to certain limitations, it is not suited to the more progressive of the listed development methods. Dynamic Application Security Testing tools are unable to be utilized on source codes which prohibits the deployment of security until the later development stages.

SAST Tools have the adaptability required to be performant across all varieties of the Sales Development Lifecycle methodologies.

They are also easily integrated into the app development environment which enables the continuous monitoring of the code. The result of this is enhanced code integrity and faster mitigation of potential vulnerabilities

Does DAST or SAST deliver a better return on investment?

As with all technology-related investments, the organization needs to know what they are going to pay out Vs. the potential ROI. Applications, whether for mobile or the web can be large-scale projects that carry a significant cost.

There are usually four key stages in the development and production of applications:

  • App Coding and Development
  • App Build
  • App Quality Assurance / Testing
  • AppSec
  • App Production

Data Breach costs are significant to any organization of any size. Irrespective of the size of the organization, the cost of rectifying an issue, and the time it takes to detect and fix a problem after production is severe.

The typical cost of rectifying a defect in the build stage could cost as little as $100 to put right. However, as you travel further through the process, this cost increases exponentially; in some cases, the cost to rectify the same issue during the testing phases could be up to $1000, and once the application has been produced could be as much as $7500.

In Conclusion

SAST Solutions have a number of distinctive benefits over DAST tools. Static Application Security Testing can help to fix bugs before the app code is complete. It offers better coverage in terms of the framework and programming languages, and it reduces both costs and risk mitigation times significantly.

SAST tools will also pinpoint the exact location of the vulnerability, whereas DAST tools will not.

Dynamic Application Security Testing will help developers to detect the vulnerabilities; the app developers will still need to go through a time-intensive process in order to find out exactly where the vulnerabilities exist.

As with all time-consuming processes such as this, there is always the cost factor to consider.

The biggest advantage any organization will have over a cyber criminal is direct access to the source code of the app.

SAST tools are able to better leverage this factor, and through the dynamic testing process, they can eradicate app later vulnerabilities.

The most comprehensive approach takes form in HAST, using a combination of SAST and DAST tools at different stages of the app development process.