The Difference Between SCA and Supply Chain Security

Right now, the concept of the software supply chain and securing it is quite trendy. After the 

Tanya Janca
August 22nd, 2023
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Software composition analysis, often called SCA, means figuring out which dependencies your software has, and of those, which contain vulnerabilities. When we create software, we include third party components, often called libraries, plugins, packages, etc. All third-party components are made-up of code that you, and your team, did not write. That said, because you have included them inside of your software, you have added (at least some) of their risk into your product. A ‘supply chain’ means all of the things that you need to create an end product. If you were creating soup, you would need all of the ingredients of the soup, you would need things like pots and pans in order to cook and prepare the ingredients of the soup, you would need a can or a jar to put it in, and likely a label on top to tell everyone what type of soup it is. All of those things would be considered your supply chain. 

Photo by Miltiadis Fragkidis on Unsplash

Imagine inside of your soup one of the ingredients is flour. Chances are that it (wheat) was grown in a field, and then it was harvested, and then it was ground down into flour, and then it might have been processed even further, and only then it was sent to you, so that you could create your soup. All of the steps along the way could have been contaminated, or perhaps the wheat could have rotted, or been otherwise spoiled. You have to protect the wheat all along the way before it gets to you, and once you make the soup, in order to ensure the end product is safe to eat.

Protecting all of the parts along the supply chain, from ensuring that there aren’t terrible chemicals sprayed on the ingredients as they grow, to ensuring that the can or jar that you put the soup into has been properly sterilized, is you securing your supply chain.

When we build software, we need to secure our software supply chain. That means not only ensuring the third-party components that we’re putting into our software are safe to use, but the way we are using them is secure [more on this later]. We also have to ensure how we build the software is safe, and this can mean using version control to store our code, ensuring any CI/CD that we use is protected from people meddling and changing it, and every single other tool we use or process we follow are also safe. 

If you’ve followed my work a long time, I am sure you know that I think this includes a secure system development life cycle (S-SDLC). This means each step of the SDLC (requirements, design, coding, testing and release/deploy/maintain) contains at least one security activity (providing security requirements, threat modelling, design review, secure coding training, static or dynamic analysis, penetration testing, manual code review, logging & monitoring, etc.) A secure SDLC is the only way to be sure that you are releasing secure software, every time. 

Tanya Janca/me

With this in mind, the difference between the two is that SCA only covers third party dependencies, while supply chain security also covers the CI/CD, your IDE (and all your nifty plugins), version control, and everything else you need in order to make your software. It is my hope that our industry learns to secure every single part of the software supply chain, as opposed to only worrying about the dependencies. I want securing these systems to be a habit; I want it to be the norm. I want the default IAM (identity and access management) settings for every CI/CD to be locked down. I want checking your changes into source control to be as natural as breathing. I want all new code check-ins to be scanned for vulnerabilities, including their components. I want us to make software that is SAFE.

If you read my blog, you are likely aware that I recently started working at Semgrep **, a company that creates a static analysis product, and recently released a software supply chain security product. If you’ve seen their SAST product, you know they’re pretty different than all the other similar products on the market, and their new supply chain product is also pretty unique: it tells you if your app is calling the vulnerable part of your dependencies. They call it ‘reachability’. If your app is calling a vulnerable library, but it’s not calling the function inside of that library where the vulnerability lives, you’re usually safe (meaning it’s not exploitable). If you ARE calling the function that is inside your library where the vulnerability is located, there’s a strong likelihood that the vulnerability could be exploitable from within your application (meaning you are probably not safe). We added this to the product to help teams prioritize which bugs to fix, because although we all want to fix every bug, we know there isn’t always time. In summary, if the vulnerability is reachable in your code, you should run, not walk, back to your desk to fix that bug.

Me, again

I have worked with more than one company that had programmers who did not check in their code regularly (or at all) to source control. Let me tell you, every single time it was expensive! Losing years of hard work will break your heart, not just your budget. Supply chain security matters.

Join me in this adventure by starting at your own office! Whether you have a budget or not, there are paid and free tools that can help you check to see if your supply chain is safe! You can also check some of this stuff manually, easily (the IAM settings on your CI/CD are just a few clicks away). Reviewing the setup for your systems, and ensuring you have everything important backed up, will make your future less stressful, trust me. 

You can literally join me on this adventure, by signing up for the Semgrep newsletter! The Semgrep Community is about to launch live free events, including training on topics like this, and we can learn together. The first email goes out next week, don’t miss out!

~ fin ~

Photo by Mika Baumeister on Unsplash

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Semgrep lets security teams partner with developers and shift left organically, without introducing friction. Semgrep gives security teams confidence that they are only surfacing true, actionable issues to developers, and makes it easy for developers to fix these issues in their existing environments.