What Is SAST (Static Application Security Testing)?

What Is SAST?

Let’s start by learning about the basic SAST meaning, i.e., Static Application Security Testing. It’s a type of AppSec testing inspired by the software verification methodology. It doesn’t ask for software execution for its analysis.

At the very core, this technique is based on detailed static & dynamic source-code analysis to find out the existing threats/errors. The code covered here is assembly code, source code, and byte code. It uses a scanner for code inspection and places the scanner at the early stage of the CI pipeline.

The other names are Source-code analysis and White-Box Testing.

As the entire focus of this method is on the inspection of the programmed modules, it’s also called Code Review. 

With continual code inspection, the technique aims to reduce the attack surface and boost the level of solution’s security. 

Mainly, SAST testing has been proven crucial for reducing the impact factor of threats like cross-site scripting, CSRF, and SQL/SQLi injection.

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How Does SAST Work?

Let’s move to the modus operandi of SAST, which is particularly based on code analysis so that any code malfunctioning is easily spotted. As the code analysis proceeds, the prime aim remains to spot the presence of SQL injection, errors, and unsanitized inputs.  

The basic processing steps are:

• Thorough analysis of the software solution
• Code analysis should be performed at each SDLC phase
• There should be a build model supporting the SAST tool
• Analysis should follow the standard rules

Now that you know how extensive code analysis happens using SAST, let us explain the five analysis types used during the process.

• Configuration analysis: It aims at checking app configuration files, ensuring that configuration should be aligned with standard practices and policies.

• Semantic analysis: The concerning entities here are the syntax, resolving code, and identifiers. The procedure involves performing the tokenization of these entities to spot the errors.

• Dataflow analysis: This analysis deals with tracking the data flow and identifying any errors before the code is made live for the app in question.

• Structural analysis: Here, error-finding is possible by analyzing the code structure. It aims to spot errors in design, codes, and variables.

• Control flow analysis: This involves analyzing the flow of operations and ensuring that it’s as per the standard process. If there is any abnormality in the operational flow, it indicates the presence of an error.

Benefits Of SAST In DevOps

The adoption of SAST in DevOps brings a lot of benefits to the table. In this section, we present to you the most promising benefits of SAST.

• Hassle-free development

The prime aim of SAST testing is to work on source code and find out any errors. Developers can deploy this testing approach at the early stage of development. As codes are written, this technique is used. Using IDE plugins and SAST deployment is easier than ever. There is not much effort and hassle to make for its development.

• Displays the exact path of problematic code

Error detection is to the point with this testing approach as it displays the exact location where the problem persists. A source code could be very long, and an error can exist anywhere. SAST highlights the code section where the problem exists. This way, searching for issues and fixation becomes easier than ever.

• There is no need for test cases

Unlike DAST, SAST doesn’t bank upon defining the test cases. The analysis rules are applied to all the codes automatically. There are no exceptions. This way, it’s possible to catch any single existing vulnerability.

• No dependency on the execution  

There is no need to wait for code execution to apply the SAST testing method. Developers can start using SAST when codes are written and formed. So, one doesn’t have to wait for execution.

• Seamless automation

Scanning automation is easy in SAST as there is no GUI interaction while text file scanning happens.  As compared to DAST, SAST automation is also quick because no set-up is required.

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Why Is SAST Important In SDLC?

SAST can be a part of SDLC and improve its viability. Now, let’s understand how it happens.

As we all know that SAST won’t wait for code execution to code reviews. Threat detection begins from the very moment codes are being developed.  

When the testing phase comes in SDLC, codes mostly come out to be perfected, and this phase is passed quickly. This increases the time-to-market. Early SAST deployment cuts down overall development time and shrinks the SDLC. 

For mission-critical applications, SAST enables organizations to speed up the SDLC and deliver the applications in record time. While delivery time is reduced, security is improved as the source, byte, and assembly codes are assessed for loopholes from the very beginning.

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What Vulnerabilities Can a SAST Tool Detect

The key reason behind the huge popularity of SAST is its far-reaching threat detection abilities. It can help AppSec experts to surface many notorious vulnerabilities. Here is what we meant.

• Cross-Site Scripting

A very common cyber vulnerability, cross-site scripting involves tricking a legitimate application used to gain access to that respective application. To make it happen, a bad actor shares a corrupted code in the form of a browser-side script and lures the client to click on it.

SAST prevents its occurrence by inspecting every code and preventing the execution of malicious ones.

• SQL Injections

Up next, we have SQL injections that SAST testing can easily fix. As well all know SAST is a notorious cyber vulnerability that can impact the database. In this vulnerability, the threat actor introduces a corrupted code to the SQL query that is part of an execution-ready request. If successful, this vulnerability can cause serious harm to the database.

SAST testing, you can enjoy fully automated code review and inspection. From the development to the deployment stage, codes are closely inspected, and any malicious element insertion will be spotted immediately.

• Buffer Overflows

This error takes place when an application writes more than usual data and keeps it as a buffer. This buffering takes place to prevent any shortage but soon becomes a headache as it provides data corruption incidences. Threat actors can corrupt the buffered codes, and developers can use them without any security review.

SAST reduces this error’s occurrence by ensuring that codes are created error-free and are reviewed before being consumed.

• Input Validation

This threat involves introducing corrupted input in an application and waiting for its impact. Based on code corruption, this attack can cause great damage. SAST tools are of a great deal of good here. They will help you figure out the corrupted code section and work on it immediately. Hence, the impact of this vulnerability is reduced or completely abolished.

Static Application Security Testing: Advantages And Disadvantages

No technology is perfect and SAST isn’t an exception. It comes with certain pros and cons. Knowing both of them is important.

Let’s talk about the advantages first.

• As it can be deployed at the early stage of SDLC, error detection can be done early.
• It doesn’t tell you that there is an error. It points out the error and tells where the issue exists.
• It’s a non-execution approach.
• It won’t keep you involved with too much configuration to enjoy the automation.

After knowing the advantages, it's time to learn about the disadvantages.

• There are incidences of false positives.
• It’s a little misplaced test and often can highlight the wrong section of the code.
• It’s a language-dependent tool and will not work if the framework and code language are not compatible with the tool’s language and framework.

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Implementation of SAST

SAST is about many good things. But, one has to be careful and try to attain the maximum possible perfection while commencing its implementation. It’s a strategic move that should only be based on a standard format. The approved SAST implementation steps are as mentioned below.

• Select a compatible SAST tool

The primary SAST implementation step is to select the suitable tool that will take care of code reviewing from the very basic stage. Make sure that the tool should be able to work with the code’s language and should be compatible with the framework used.

• Construct the scanning ecosystem

Once you have selected the tool, you must start working on setting up the scanning ecosystem that is mainly concerned with handling the licensing, access control set-up, hiring the right tools, and set-up the role-based access.

• Fine-tune the tool

Pre-build tools will lack a bit to address your scanning requirements without fail. Hence, you must perform basic tool customization. The most common tool tweaking practices are modifying the configuration to ensure there are fewer false positive incidences and integrating the tool directly into the scanning ecosystem.

• Load the application

Now that the tool is all set to perform scanning, you must upload the concerning app. If there is more than one app for scanning, prioritize them. Find out which app needs immediate attention. Apps with high risk should be scanned first. You can upload multiple apps in the order of their risk factor.

Also, make sure that you synchronize the applications regularly. If the code is updated and new features are added, upload the most recent application version to get the best code scanning results.

• Pay attention to the scanning results

Once you have scanning results in your hand, analyze them closely and try to find out false positive incidences, if any.

• Conduct training and govern the tool usage

You must ensure that the code review is going according to the expectations. For this to happen, the team should be trained, and the tool’s penetration and usage should be governed. Try to find out any usage hindrances and arrange team training to fix them.

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How Does SAST Combine With Other Testing Methods?

SAST is not the only testing method that the AppSec world has. There are multiple options, and SAST can be paired with others. At the very basic level, SAST is all about code scanning. Those who are using DAST can combine SAST with DAST and enjoy empowered code security.

DAST is all about input and output inspection. Code review is not at all involved. But, when paired with SAST, DAST performs code inspection and input/output validation as well. They both are so compatible with each other that it’s not erroneous to call each other two faces of one coin.  

But, when these two are combined, testing speed can slow down a bit. For complex apps, DAST is already sluggish, and implementing SAST will make things a bit more slow. There is a fix available. One must deploy SAST at the early stage. Generally, CI/CD pipeline and IDE are perfect for its implementation. Let DAST work at the later stage.

As far as IAST and SAST are concerned, we don’t think that they two get along well. It’s because of an entirely different workflow and test process. IAST is a dynamic approach that tests the codes in real time. 

App remains functional while the code review continues. SAST reviews the code before the execution. So, there is no point in using SAST when IAST is in use, as code will eventually be reviewed as it becomes part of an application.

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5 Tips Before Buying a SAST Tool

A SAST tool is a great way to attain automation and accuracy in a testing strategy. It’s not erogenous to deduce that the success of SAST testing mainly depends on the quality and viability of the SAST tool.  

Thankfully, we have many choices. A wide range of paid and open-source options are available. You need to decide which one is the ideal fit for you. Even though the task seems too tedious, a little diligence can make things possible.

Keep the below-mentioned tips in mind while you select a SAST tool for code testing:

1. Compatibility with the programming language

You need to find out which languages a tool can handle. Often scanners can only scan the codes written in a compatible coding language. For example, a Python-based scanner will only work with Python code. What if your application uses codes written in a different language?

You need to spend some time to analyses which programming codes you have used in your application and which languages for coding the scanner is supporting. Compatibility on this front decides the success of the SAST testing strategy.

2. Don’t hesitate to ask for a demo

Even if a tool claims to be an easy-to-use tool, checking its operational seamlessness matters a lot. Don’t hesitate to check how comfortable your team is while using the tool. Its technical specs should follow the technical competency of the teammates.

The ideal way to figure this out is to conduct a demo. Go for the tools offering a demo facility as it will make things excessively easy.

3. Types of vulnerabilities it can handle

The prime aim of using a SAST security tool is to detect vulnerabilities. A tool that is capable of detecting as many vulnerabilities as possible is indeed a great choice to make. There is no point in using a half-good tool as you have to invest in other options as well. Hence, investigate the loopholes that a tool can easily detect.

4. Level of false positive incidences

A tool offering too much false positive reporting is problematic. With high false positive reporting, your testing will hardly provide any assistance. Hence, you need to make sure that the tool you’re trying to use is providing fewer false positives.

5. Check the license of the tool  

Don’t overlook the licensing aspect of the tool. You need to make sure that the tool you’re trying to use is legally licensed and adheres to the best compliances as well. Some of the factors to check out here are the renting model, flexibility in licensing, and feature customization.

Keep these things in mind, and you will end up having the aid of a quality SAST tool with the least possible hassles.

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Summary

SAST is one of the most preferred source code review and testing methodologies that AppSec experts use to detect multiple kinds of threats. The post covered almost everything related to this technique. Let’s have a quick review.

• SAST is a static process and can be deployed at the early stage of SDLC.  
• Code review and testing can continue with code designing and development.
• The approach is easy to use, can test code from the early stage, doesn’t demand a test case, and can highlight the exact location of problematic code.
• Its proper implementation leads to early SQL injection, CSRF, and input validation sort of vulnerability detection.
• Various SAST tools help automate the entire process and improve accuracy. While you plan to use a tool, make sure that it’s easy to use, provides fewer false positives, and has flexible licensing.

We hope that now you’re aware of every key pointer about SAST. Start your testing journey today with SAST and improve your application security, which is an imperative SDLC aspect.