Exploitability is the Missing Puzzle Piece of SCA (Software Composition Analysis)

Open-source libraries allow developers to move faster, leveraging existing building blocks instead of diverting resources to building in-house. By leaning on existing open-source packages, engineers can focus on complex or bespoke elements of their products, using package managers and open-source maintainers to make it easy to pull everything together.

However, you can't deny that building software using open source makes your applications more vulnerable to security risks. In an open-source library, attackers have direct access to code, and can search for current and historical vulnerabilities, as well as any issues and tickets managed on websites such as GitHub or GitLab. This helps threat actors to quickly find packages that are vulnerable and launch an attack.

This is where Software Composition Analysis (SCA) comes in, with the purpose of scanning packages and uncovering vulnerabilities. SCA compiles and manages a catalog of software packages, alongside details such as their versions and components, helping engineering teams to quickly identify risk.

Today, with so many problems that can surface at the same time — it's no longer enough.

Understanding the Level of Risk by Exploitability

Imagine someone giving you a list of weaknesses in your home. You have a faucet that is disconnected, and two smoke alarms that need replacing. Four of your locks aren't strong enough, in fact — one doesn't work at all. You may immediately pick up the phone to a plumber and a locksmith — as you can't live without running water, and you're worried about opening yourself up to the risk of a burglary.

However, if you knew that the faucet in question was in the back yard — which you haven't used in years, and the faulty lock is on the en-suite bathroom rather than your front door, your priorities may change. In fact, if you knew that it was your kitchen that didn't have a functioning smoke alarm, voiding your insurance, that may well jump to the top of the list of priorities, and become the first problem you fix.

This is exactly what understanding exploitability provides in Software Composition Analysis — the visibility to recognize where you should be prioritizing efforts, and which vulnerabilities translate to business impact. If you have a library of functions and you don't use the vulnerable ones, the level of exploitability is far lower than it might first appear. If you can disable a feature so it's no longer utilized, then the vulnerability it holds is not as readily exploitable, which means it's no longer critical to fix as quickly as possible.

Prioritization, Compliance and Urgency

Of course, the best practice is to only use secure packages — and our recommendation will always be to upgrade unsecure components and packages. However, we also recognize that in reality, not everything can be done at once.

Most teams have thousands of items on their to-do lists, and are continually tasked with prioritizing efforts and intelligent resource allocation. Focusing on exploitability can ensure:

• Prioritization: Where should efforts be expended first? Tempering risk with exploitability gives you the chance to be granular about when and how you should fix a weak package.
• Compliance: Many regulations have different requirements for critical vulnerabilities compared with what you do when facing more moderate threats. Exploitability helps teams to understand their responsibilities in terms of reporting.
• Relevance: In some cases, vendors determine something is weak or exploitable and there is no fix at all. Understanding exploitability lets you make an informed decision about whether you can still use it, with an accurate understanding of risk.

Using Exploitability Metrics to Get the Full Picture

So, how do developers obtain visibility into exploitability? One powerful approach is using a platform that supports metrics such as the Exploit Prediction Scoring System (EPSS). This weighs the likelihood of being exploited based on factors such as availability and vendor response. For example, if this is a new exploit without a fix, the EPSS score is very high, while an exploit that has been around for years and has a fix would score much lower. With EPSS, you can understand the temporal status of an exploit, which will be highest for widely used zero-day exploits before a fix has been found, compared with when an exploit is uncovered and disclosed by a responsible researcher for example.

Alongside the baseline CVSS and additional metrics such as Known Exploited Vulnerabilities (KEV), at Checkmarx we work to fine-tune exploitability so that your teams can focus attention where it's needed the most.

Taking it further, the ability to visualize what we call the Exploitable Path flags exactly what's being used by each package, so that you can understand your immediate risk better in terms of exposure. If you're not using a vulnerable element, or your specific configuration is not vulnerable, you can prioritize elsewhere. While the best fix may still be to update or disable, you have all the information you need to manage your own risk.

For today's development teams, prioritization is a complex task, and competing necessities are a constant reality. At Checkmarx, we take SCA further than a simple catalog of packages and vulnerabilities, and provide the essential insight and visibility into whether a vulnerability is exploitable in your environment.

For a deeper dive into how exploitability analysis can optimize your remediation efforts, download the FREE Tolly Report commissioned by Checkmarx, a global leader in application security testing. This independent evaluation compares Checkmarx SAST and SCA solutions against leading competitors, showcasing how Checkmarx delivers unmatched accuracy. Read the report now to learn how Checkmarx empowers you to effectively prioritize vulnerability remediation.