What is SAST?
Static Application Security Testing or SAST is an Application Security Tool that is frequently used to scan an application’s binary, source, or byte code during the development cycle or code reviews. A white-box testing tool can identify the root cause of vulnerabilities and help in remedying the underlying security defects. Many SAST tools can analyze an application inside-out and it doesn’t require a running system for performing a source code analysis to find security vulnerabilities.
Static application security testing can reduce security vulnerabilities in applications by offering immediate feedback to developers on problems introduced in the source code during the application security testing. So, it educates developers about security flaws when they are working, offering them real-time access to line-of-code navigation and recommendations that allow faster collaborative auditing and vulnerability discovery. A SAST tool helps developers create secure code that is less vulnerable to compromise and leads to the development of a more secure application.
However, SAST tools can’t identify vulnerabilities outside the code. For instance, vulnerabilities found in a third-party API won’t be detected by SAST analyze scan results and would need Dynamic Application Security Testing by the security teams.
How Does Static Code Analysis Work?
Static code analysis is a technique of gauging an approximate program’s runtime behavior in the software systems. In simple words, it is the coding process to predict a program’s output without really executing it to detect vulnerabilities and offers developers potential solutions.
However, the term ‘Static Code Analysis’ is used to refer to an application of the technique instead of the technique itself, which is program comprehension. It is all about understanding the program and finding out the problems in it. In this article, we will talk about this usage of the technique.
Before your system understands and executes a piece of your source code, it will go through a series of complex transformations. To understand the static analysis technique better, let’s check out the SAST scans step in detail.
One of the first things that the compiler does as it tries to understand a piece of source code by breaking it down into parts is called tokens. Tokens are similar to words in a language. So, a token can have either one character, such as (strings, integers, etc.) or reserved keywords of the language. Characters that don’t contribute to the program semantic, such as comments, trailing whitespace, etc. are usually discarded by the scanner.
Python offers tokenize modules in the standard library so that you can play around with the tokens. It helps in identifying vulnerabilities and data breaches for managed services.
By now you have an idea about the vocabulary of the programming language. However, the token by themselves doesn’t reflect the language’s grammar. That’s where the parser comes into play and offers app owners the ability to test code with the correct security expertise.
A parser will take the token, validate their sequence confirming to grammar, and organize them in a structure that looks like a tree. This represents a high-level structure in a program. It is known as Abstract Syntax Tree. Abstract as it abstracts away low-level insignificant details, such as indentation, parenthesis, etc. letting the user focus just on the program’s logical structure. This is what makes it the ideal choice for performing static analysis.
A syntax tree can be complex and large. Hence, it makes it arduous to write a code to analyze it to ensure code security covering the additional security vulnerabilities. What’s good is since it is something that all compiles perform all by themselves, some tooling exists to simplify the whole process.
Python ships using an ast module as a part of the standard library. In case have worked with AST that much, check out how the module works.
- All AST node types are represented through the corresponding data structure in the ast module.
- To build an AST from source code, use ast.parse function.
- To analyze the syntax tree, you need an AST ‘walker’, which is an object to facilitate the traversal of the tree. The ast module provides two walkers.
- ast.NodeTransfomer that allows modification to the input tree
- ast.NodeVisitor that doesn’t allow modification to the input tree
- While traversing a syntax tree, you should just analyze a few interesting nodes. For instance, if you are writing an analyzer that will warn you if you have over 3 nested for loops, you should only visit ast.For nodes.
- To analyze a certain node type, the walker has to implement a special method. It is a method that is often known as the visitor method. So, the Terminology: to visit a node is nothing but only a call to the method.
- These methods are called visit_+<NODE_TYPE>, e.g. for adding a visitor ‘for loops’. The method has to be named ‘visit_For’.
- There is a top-level visit method that recursively visits the input node that is it first visits itself and then the children nodes. Thereafter, the children nodes or the children nodes, and it continues.
Python also has many third-party modules, such as astmonkey, asteroid, astor that offer added abstract modules for making lives easier.
List and a Short Description of Commercial SAST Tools
Here are the top commercial static application security testing tools that you can consider.
Fortify Static Code Analyzer
This application security testing SAST tool has been created by Micro Focus. It can be harder to integrate than other solutions in the software development process. However, it does support build tools, IDE, bug tracking, and code repository.
Once you set it up, the security practitioners or developers will like the application security testing methods offered by this SAST tool. The tool can produce traceable vulnerability information and supports 25 languages for Android and iOS apps. If you want, you can manually clean the false positives without any hassle.
SAST is an integral part of Synopsys Software Integrity Platform portfolio that includes technology collected from Codiscope, Cigital, and Black Duck Software. The portfolio has a wide range of testing technologies, such as SCA, dynamic application security testing, white box testing, and Interactive Application Security Testing. Coverity got an upgrade from Synopsys and that improved its capabilities.
Coverity scanning infrastructure allows the software to scan more vulnerability types across various programming languages. Also, this static analysis tool can perform static code analysis without collating codes for languages, which have an interpretive nature.
Apart from SAST, the tool also supports Software Composition Analysis and Dynamic Application Security Testing. What’s even better is the status of the application across all testing can be checked through one dashboard. This is an app, which has been designed for a developer. It includes an API to customize the software.
So, when it comes across a vulnerability after the static and dynamic analysis, it tries to solve it. In case you are using Jira, Veracode can open tickets with the right development teams if it comes across any security flaws in the code quality. This helps in generating valuable statistical details about the app and the code security quality.
AppScan was recently sold to HCL. It is one of the SAST tools that allow an organization to implement a scalable security strategy, which can point out and remedy the vulnerabilities of an application during the development process. The tool can test mobile, web, and open-source software. In fact, it can also offer reporting and management tools for multi-app, multi-user deployments.
All deployment choices are flexible and have on-premise, hybrid, and cloud offerings. The secure software has been lauded for its lower rate of false positives or its feature to counter any application attack.
List and a Short Description of Open Source SAST Tools
Here are some open-source SAST tools that you can consider using.
Reshift is an open-source developer-first security tool created to work within the existing environment of the developer without slowing down the pipeline. The tool can be integrated with Bitbucket, Github, and Gitlab where it can easily sync projects and scan every build. Moreover, it allows custom security policy settings for various high, moderate, and critical issues where it fails the build in case the threshold exceeds.
Since the focus is on the tool created for developers, Reshift offers ‘automated fixes’ where suggested solutions are listed and developers can accept to develop a pull request, and remedy with a little friction. Its remediation assistance lets development teams who are not security experts get to know about the critical vulnerabilities with real-world impacts, overviews, suggested fixes, and resources.
A development team that works with Node.js can use this static application security testing tool for scanning their source code security. The software comes with a command-line interface that makes it easier to integrate with DevSecOps CI/CD pipelines. It produces outcomes in JSON and supports many programming languages, including C++, Java, PHP, VB, C#, and PL/SQL. There is a configuration file for every language that can be modified for personalized searches and the security assessment framework capable to perform the application security analysis.
It is a free vulnerability scanner that has been designed for Ruby on Rails apps. The software will analyze the Rail app code and identify vulnerabilities at any stage of the development process. Many users have lauded the program for the accuracy and speed of its cans and for offering remediation details that the developers can understand.
It is one of the open-source SAST tools that has been developed under the sponsorship of the University of Maryland. It has been created to catch bugs in Java code through static analysis. However, the application has not been updated in a while. The new 3.0.1 version was released 0n March 2015. The tool scans can classify bugs and vulnerabilities that they find in 4 rankings: of concern, troubling, scary, and scariest. The program is capable of finding defects in 15 categories. However, reports can be personalized. Thus, just a subset of categories is reported on.
Implementing static analysis security testing tools can offer many advantages to a business. It will help in identifying security vulnerabilities. With so many mobile application security testing SAST tools available in the market, it can be difficult to choose one. However, you have to be aware of the languages that these SAST tools support for the software development life cycle.
Also, don’t forget about the false positive rate of these SAST tools. Some SAST tools, such as Findbug are open-source but to use that, a tester should have a complete understanding of the QL language. Thus, the process to implement it might be a little longer to have a secure code for the application. On the other hand, there are some SAST tools that aren’t updated anymore, and the testing team has to be more careful when choosing a tool for static analysis security testing.
If you are looking to implement static application security testing, reach out to us. Get complete peace of mind as we will help you in application security testing with SAST tools to fix security defects.