Real-time container vulnerability scanning tools have become an essential part of secure software development. Here’s how everything fits together
If you’re an AppSec pro over a certain age, you’ll remember the rules for Mogwai: Don’t expose them to light, don’t let them near water, and never feed them after midnight. Break the rules and you’ve got a monster on your hands – one that multiplies faster than you can keep up.
What’s that got to do with container vulnerability scanning? Well…
You could start with just one vulnerable base image sitting quietly in a registry. But then someone pulls, reuses or otherwise bakes it into another microservice and it’s like splashing water on Gizmo: It multiplies. Fast.
A single flaw can replicate across hundreds, or even thousands, of running containers in seconds. Before you know it, you’ve got new vulnerabilities capable of compromising the entire application stack. The Gremlins are loose in the container runtime – and unlikely to stay quiet for long.
That’s why real-time container vulnerability scanning tools have become an essential part of secure software development. Here’s how it all fits together.
Container Vulnerability Scanning: Why it Matters
First things first: by “container”, we mean Docker, Kubernetes, AWS Fargate, and others used by software developers to build and manage applications (for a more in-depth explanation of container environments, check out this post). Between them, they’ve revolutionized the way we build and deploy applications, bringing unparalleled flexibility, consistency and scalability. They play a critical role in modern, accelerated CI/CD pipelines: Lightweight, standalone packages that include everything needed to run a piece of software – code, libraries, settings – so that it works in the exact same way, everywhere. For example, you can open a Docker image, run it in AWS or Azure, and begin to develop the software. Containers often include third-party code, open source libraries, and dependencies – as we’ve seen in other areas of software development, this can introduce a lot of risk.
For developers, containers make it easy to build, test, and deploy apps quickly and consistently. For application security teams, containerized environments can be a source of new vulnerabilities and risk, such as vulnerable images or misconfigurations. And as we saw with the Mogwai analogy, a single flaw slipping through the cracks is rarely about just one container – it’s usually a full fleet of them, with significant implications for software supply chain security.
Common Vulnerabilities Detected in Containers
Before we look at some of the container vulnerability scanning tools AppSec teams use to detect and resolve security vulnerabilities, let’s take a look at some of those vulnerabilities:
Insecure container images:
Base images that are not regularly updated or reused from unauthorized/unofficial sources often carry vulnerabilities or embedded malware.
Excessive privileges:
This includes containers running as root or with the –privileged flag or unnecessary Linux capabilities (most likely to be used in containers). .
Misconfigured secrets:
Hardcoded credentials in environment variables, files or Dockerfiles are common vulnerabilities detected.
Container escape attacks:
These vulnerabilities are runtime-related, and not detected directly by scanners, but misconfigurations that enable escape are flagged.
Access control issues:
This includes poor role-based access control (RBAC), a core security mechanism in Kubernetes and other container environments. Poorly configured access controls can allow attackers to escalate privileges and access sensitive resources.
Known vulnerabilities in open-source packages:
One of the most common, critical risks in containerized applications – one vulnerable library can affect millions of applications (as we saw with the massive Log4j vulnerability, which many teams didn’t know was inside their containers). Once disclosed, attackers can automate exploitation of known Common Vulnerabilities and Exposures (CVEs).
Outdated or insecure dependencies:
The impact of these is often amplified in containers, because images often retain a ‘frozen’ snapshot of the application’s environment, including vulnerabilities. Even if the vulnerability is patched upstream, they stay locked in running containers until the image is rebuilt.
As containers have grown to become mainstream, they’ve become a tempting – and often highly effective – target for attackers, as some high profile breaches show.
What Does a Container Vulnerability Breach Look Like?
For an idea of what the damage can look, like, a brief overview of some high-profile exploits impacting containerized apps include:
- Log4Shell / Log4j: The vulnerability that led to new U.S government directives around securing open-source software, and accelerated the adoption of tools such as Software Composition Analysis (SCA), Log4Shell underlined how a single, very small feature in one ubiquitous library could put the entire internet at risk. Because it’s buried in a transitive dependency, it often goes undetected in container layers – and mitigation is complicated by the frozen dependencies issue mentioned earlier, meaning that organizations that don’t regularly rebuild images were effectively packaging vulnerable code.
- Tesla: In 2018, attackers were able to access the automakers’ Kubernetes admin console (it wasn’t password-protected). From there, they deployed malicious containers that were used to mine cryptocurrency. This attack underlined the importance of secure configuration in container security.
- Docker Hub: This breach in 2019 created a ‘Trojan container’ scenario in which an attacker could have used stolen access tokens to create malicious files or container images. A user pulling that image into their CI/CD pipeline, believing it to come from a trusted source, would unknowingly deploy malicious code into their own workflow, with potential impact on the wider software supply chain. Because many organizations use public container images from Docker Hub, often with little or no verification, a successful attack had the potential to cascade into a massive supply chain issue.
What Can We Learn from Breaches in Container Security?
All of these incidents exposed the fragility of an ecosystem that, for a long time, had effectively operated on trust. Docker Hub code was routinely deployed without validation, many development teams had little or no insight into who maintained the public images their applications depended on. Few were using Software Bills of Materials (SBOMs) to gain visibility into containers.
Even though Docker Hub acted quickly and no official images were affected, the breach underlined the reality that even a very small number of vulnerabilities could have far-reaching impacts on the global software supply chain: It impacted approximately 5% of the user base (around 190,000 accounts).
Organizations of all sizes got a wake up call on the need to implement more robust security practices across the SDLC. Container vulnerability scanning tools were deployed to help identify security issues before they hit production.
What is a Container Scanning Tool?
The need for container security scanning tools is clear; they help identify known vulnerabilities, as well as potential threats in container images and containerized applications. A container scanning tool analyzes the content of an image, often starting with base images, and compares the code against databases of known vulnerabilities. This helps security teams to identify risks such as outdated packages, unpatched vulnerabilities or insecure configurations before they can be deployed into production.
From privilege escalation to malicious code injections, risky configurations, data theft, and code tampering, a container security scanner helps to detect vulnerabilities and prevent them from being exploited. When it comes to container scanning tools, there are different types, each focusing on different aspects, including:
- Image vulnerability scanning: This focuses on CVEs / known vulnerabilities in image layers, typically in the build stage of container image scanning.
- Static Application Security Testing (SAST): Source code scanning, focusing on insecure code during the development stage, before it’s built into a container.
- Software Composition Analysis (SCA): Dependency scanning, looking for vulnerable packages during the development and build stages.
- Configuration scanning: This looks for risky misconfigurations in Dockerfiles and Kubernetes manifest, usually during pre-deployment or review.
- Runtime scanning: Checks for vulnerabilities, suspicious behaviors, and policy violations during runtime, at the production stage.
- Signature verification: This helps to confirm image integrity (who built it, has it been tampered with etc) at deployment and governance stages.
- SBOM generation and analysis: A software bill of materials maps every component in a container, enabling full analysis of risk and licensing issues. SBOM management for container security gives AppSec and developer teams deep visibility into their code.
A typical container security scan will involve several of these tools and techniques, each playing a different role in container vulnerability management.
Automating Container Scanning in CI/CD Pipelines
Given the high prevalence of vulnerabilities – and the even higher stakes in terms of software supply chain security – proactive scanning of containers is critical. In today’s accelerated SDLCs, teams increasingly automate container vulnerability scanning, integrating it into the CI/CD pipeline for maximum effect. Most of the tools we just looked at can be used in this way, enabling teams to automatically fail builds if critical vulnerabilities are detected, authenticate, or generate reports. The benefits of automating scanning in CI/CD pipelines include:
- Early detection: Early detection of issues before production is a crucial aspect of shift left security.
- Save time and costs: Early detection prevents issues from emerging later in the process, when they’re often more complicated and expensive to resolve.
- Improve consistency: Automated workflows and processes enhance consistency, which in turn facilitates compliance efforts.
- Enforce policies: Automated checks and enforcement removes manual overhead, and ensures that policies are applied across the board.
One crucial advantage of integration container scanning with AppSec practices is the ability to perform contextual analysis. This linked container vulnerabilities directly back to the source code, shedding light on where a problem lies, how it was introduced, and how to remediate it. Teams that can create a direct link between container issues and source code vulnerabilities can bridge the gap between container security and code-level issues. This makes vulnerabilities more actionable, and remediation more precise.
Integrating and automating container scanning with DevOps transforms AppSec into a frictionless layer in the CI/CD pipeline. With best practices integrated into the way teams build, test and release software, security is baked in from the get-go, rather than bolted on at the end. The result: faster, more secure release cycles and an improved overall security posture.
All good. But all this accuracy and precision can come with its own set of challenges, not least false positives. What can you do about that?
Reducing False Positives in Container Scanning
Application security can be a little like airport security: you can’t open every single bottle of water, but you can piece together a lot from observing the overall picture of the person carrying it. In other words: Context matters. And it’s one of the key aspects of minimizing false positives in container security scanning. Let’s take a look at this, and some other best practices:
- Take a context-aware, risk-based approach: Advanced tools provide context-aware scanning that maps to your risk profile, prioritizing vulnerabilities that are actually exploitable and reachable in your organization. For example, you could have a container image with an outdated version of OpenSSL, but your application never uses it, so you can deprioritize mitigation.
- Tune your configurations: Regular updates to signatures improves accuracy and minimizes outdated triggers. Dial back aggressive settings to match your environment’s risk profile, and include known non-issues, leaving room to focus on genuine risks.
- Continuous monitoring and refinement: Related to the above point, schedule regular audits to ensure triggers are up to date, and adapt to new threats. Document any recurring false positives and update workflows accordingly.
- Don’t forget the humans: Align with development teams to define risk priorities and refine detection rules. Apply human expertise to validation of high-risk alerts.
Smarter, more advanced tools reduce the noise of unnecessary alerts, filtering out vulnerabilities in unused paths or inactive components. But how can you be sure your tools are the smart ones?
Key Features to Look For in a Container Scanning Tool
Context also plays a role in choosing the right container scanning tools. AppSec teams need to consider more than surface-level detection capabilities; they need to know how well a tool can fit into existing development workflows, how it prioritizes real-world threats, if it can provide actionable insights for remediation, and if it can automate those remediations.
With that in mind, let’s take a look at some of the key features to look out for in an advanced container vulnerability scanning tool:
Context-aware prioritization:
Choose a tool capable of identifying the threats that matter most to your container environment, based on runtime risk, exploitability, reachability, and business impact.
Integration with CI/CD pipelines:
The ability to automate scanning at the build stage, before code hits production, helps teams block bad builds early in development.
Dependency and source attribution:
It’s one thing to know you’ve got a vulnerability, and another to know where that code came from. Tools that let you map container vulnerabilities to their origin in the codebase enable more precise triage and remediation.
SBOM generation:
SBOMs are the ingredients guide to what’s inside your containers. Look for tools that can automatically generate and store SBOMs as part of the build process – they’ll make life easier for audits, compliance and incident response.
Runtime context and reachability analysis:
If the vulnerability is in a package that isn’t used, it doesn’t have to be a priority. Look for tools that can perform runtime-aware scanning to single out vulnerabilities that are actually reachable in your code path, ensuring the security of your operating system.
Aggregation across sources:
If you’re using multiple scanners and tools, you can save yourself a lot of headaches by making sure they all talk to each other. The best tools correlate findings, and consolidate them into a unified risk view.
Developer-friendly insights:
If developers can’t understand or act on scan results, all you’re doing is making noise. Look for tools that provide developer-focused remediation guidance – better still, ones that include automated fixes – and you can minimize security bottlenecks.
The best container scanning tools do a lot more than *just* detect vulnerabilities. As we’ve seen, the best tools enable prioritization and integrate with CI/CD workflows to support faster, more informed remediation.
Visibility goes a long way
At the end of the movie Gremlins, order is restored when a skylight is opened exposing the out of control “Stripe” to sunlight, expediting the kind of gruesome end you have to be 14 to truly appreciate. For AppSec pros trying to secure their container environments, it turns out that light – in the form of deep visibility – has a similar effect on malicious or unsecured code.
Automated scanning reveals vulnerabilities in base images, application layers, and dependencies. Policy enforcement – clamping down on misconfigurations, exposed secrets, risky dependencies – is the “Don’t feed them after midnight, and keep them away from water” side of bad practice metastasizing into big trouble.
The right tools help teams to focus on the 5% of threats that matter most, and keep the potential troublemakers away from production code.
OX Security: Complete Security and Visibility for Containers
Ox Security’s end-to-end container security capability integrates into development pipelines, giving teams complete visibility into container images, configurations, and dependencies. Now you can detect and eliminate container vulnerabilities and misconfigurations before they reach production, reducing risks to your software supply chain.
OX’s seamless integration into CI/CD pipelines ensures that security is embedded into every stage of the development lifecycle, from code to cloud.
Turn container chaos into confidence with OX, book a demo today.
)
