Why SAST and DAST are Crucial for The Security of Web and Mobile Applications?

Posted DateFebruary 18, 2021
Posted Time 5   min Read

A huge chunk of cyber risks faced by businesses is a result of attackers exploiting known vulnerabilities in the applications. These loopholes could have been introduced via gaps in patch management, and bad coding practices.

You probably ask yourself, is it hard to develop secure code? Yes, it is quite difficult. In fact, you’re asking the wrong question. The appropriate question to ask would be: How do I ensure I get visibility into the security risks of the application at all stages and take steps to mitigate it?  By reframing the question in this manner, the right set of tools and approaches at different stages in the SDLC can be put to best use.

For many enterprises, the answer to this question is still yes since the security vulnerabilities can be at any stage of software development. The good news is you can defend a huge amount of risk scenarios by using application security testing tools as an integral part of the SDLC. WAF, RASP, SAST, DAST & IAST are significant technologies, which can be used to guarantee secure application. Each of these technologies has its own role and is used in a specific phase of the SDLC.

Among them, SAST (Static Application Security Testing) and DAST (Dynamic Application Security Testing) are two different security testing tools, which adopt a unique approach to solve app security issues. Let’s depict the strengths and weaknesses of these approaches and why to use both for thorough and accurate security testing.

What is Static Application Security Testing?

SAST is also known as white-box testing, which tests the inner workings of applications – testing occurs from the inside. SAST tools test the source code and highlight the flaws/vulnerabilities in the code, evaluate the code resilience, and help developers to fix those vulnerabilities earlier in the software development life cycle.

The SAST can be performed in various stages of SDLC hence it is easier for the developers to discover the root cause of the issue within the source at a faster rate. As it is dedicated to discovering source code issues, they are usually used in Agile and DevOps environments. SAST tool doesn’t analyze the apps from a functional point of view, which requires the tools to test the app from the attacker’s perspective.

Advantages of SAST Tools

  • Fixing vulnerabilities is less expensive as it uncovers them earlier
  • Highly scalable security testing solution
  • It is ideal to detect vulnerabilities, which can be discovered automatically like SQL injection flaws
  • Determines the exact location of a flaw, it aids developers to locate weakness and address them promptly
  • Offer real-time visibilities of threats with graphical representation and will be able to identify risks such as buffer and memory leak risks better than a DAST based approach
  • Supports automation

Limitations of SAST Tools

  • SAST tools work on abstract models of application logic and data flow, hence there is more chance of false positives
  • They are often difficult to use
  • SAST tools demand access to the source code, byte code, or binaries of the application – the details that most companies hesitant to share with app testers or managed security service providers
  • Tied to the above point, the setup is more intrusive and has a dependency on the IDE and the language on which code is developed for the tool to be effective
  • They can’t determine flaws in the run-time environment like vulnerabilities that might be uncovered in 3rd party interface
  • Not capable to check the call or argument values or do behavioral based run time testing with checks on character limits, and junk data behavior

What is Dynamic Application Security Testing?

DAST also known as black box testing, discovers security vulnerabilities in web apps from the outside. This tool is used at the end of the development cycle to find the run-time vulnerabilities and environmental issues. Dynamic testing methodology stimulates realistic attacks to detect loopholes beyond the application’s source code. It implements fault injection methods like XSS, SQL injection, etc to add malicious data to the given application to examine its behavior.

This approach evaluates the server configuration and authentication issues, checks for logic misconfigurations, detects 3rd party component flaws, attempts breaking the encryption from outside, etc. This customizable and flexible security testing tool can be used for vulnerability assessment of apps of all sizes.

Advantages of DAST Tools

  • DAST tools don’t require implementation and deployment details of applications to scan for vulnerabilities
  • The only testing approach of Web APIs
  • With stimulating the actions of hackers, discovers a wide range of vulnerabilities, which may be missed by other application security testing techniques
  • Language independent
  • Evaluates resource usage and memory consumption
  • Checks the entire system and application
  • Tests for cross-site scripting, SQL injection, and cookie manipulation attacks
  • Understands arguments and function call

Limitations of DAST Tools

  • Identification a bit later in the SDLC cycle, but this can be mitigated by having this run also as an integral part of the QA cycle
  • It will be limited in detecting source code related issues and checks on risks such as buffer overflow, parameter references during function calls
  • Limited to test only web applications and services
  • Could have slightly higher false-positive risks, but can be mitigated by also doing a POC along with automated results

SAST vs DAST: Difference between SAST and DAST Testing Tools

1 Takes the application developer approach Takes the hacker’s approach
2 Tests application issues Test environment and runtime problems
3 Supports evaluations of real-time systems, Sequential design process environment, and mobile apps on embedded devices Supports evaluations of web apps & services, databases, caches, and servers
4 Detects both client-side and server-side vulnerabilities with high accuracy Analyzes only requests and response as such the hidden flaws like design flaws goes unnoticed

Using Both SAST and DAST Tools

No single security tools will detect all types of security problems. It is best to prepare for a combination of tools. By automating the test for source code flaws, spotting security flaws can become a routine. SAST is the common beginning point for initial code analysis, which helps to fix the common vulnerabilities and aids developers to make sure code adheres to industry standards. Not all cybersecurity risks are detectable at the development stage, particularly when the code is unavailable.

Most risks are only unearthed when the app is in use; hence, there is a need for DAST testing tools, which check a running app before scanning it. Thereby all the exposed access points and inputs within the app are uncovered, which then subsequently tested by the scanner for a range of weaknesses. It also assesses how the interaction of different components within the app affects security – an important factor, which reduces the attack surface of your application.

The right combination of application security testing tools can reduce time to market and cut down the cost of development, maintenance as well as remediation. Static Application security testing and Dynamic Application security testing can be used together. The outputs of DAST can be used to refine the rules of SAST testing, boosting early vulnerability identification. As a result, you can use SAST as the primary method for threat discovery and DAST for a verification check before the application is pushed to production.

Security Testing with Indusface

Indusface offers a comprehensive suite of cloud-based solutions for application security testing, which simplifies the cybersecurity management process. Combining with automation, Indusface’s SaaS-based security service seamlessly integrates security into development and enhances web application security without requiring additional equipment and staffs.

Ending Notes

Implementing SAST testing is a great approach to reduce the number of vulnerabilities, which are appearing in new code, but once a large application is running with its complete modules, configuration parameters and dependencies, nobody can be 100 percent confident about what is going on inside. That’s why DAST security testing is mandatory.

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