Open Source Attack Surface Management (ASM) Guide

In an age where organizations are facing difficulties with complex digital environments, Attack Surface Management (ASM) is becoming a key component in modern cybersecurity strategies. At its core, ASM is the continuous activity of discovering, recording, classifying, and monitoring all digital assets that may be abused by threat actors. These could be public-facing web applications, internal networks, public cloud resources, and, critically, open-source components stitched or compiled into the organization’s technology stack.

When companies rely on open-source libraries, frameworks, and tools to accelerate development and reduce expenses, they must also contend with the security risks associated with those dependencies. Open-source attack surface management is a more significant concern than ever following the older SolarWinds and the more recent Log4j incident, where vulnerabilities were found in an open-source component, which resulted in the widespread attack on a number of enterprises.

What is Open Source Attack Surface Management?

Open-source attack surface management refers to the practice of identifying, monitoring, and mitigating risks due to open-source components within the technology infrastructure of any organization.

While traditional ASM focuses on perimeter and externally visible assets, Open-source ASM digs deeper into the software supply chain and looks into the libraries, frameworks, and packages that constitute the building blocks of modern applications. This realization acknowledges that vulnerabilities are not exclusive to an organization’s own code but rather are inherent across the extensive ecosystem of third-party open-source dependencies on which applications depend.

Traditional ASM is typically centered around discovering and monitoring network endpoints, domains, IP addresses, and other externally exposed assets. Open Source ASM expands this view further inward, looking at the composition of applications themselves. It involves creating and updating a complete software bill of materials (SBOM), collecting version information and known vulnerabilities in dependencies, as well as understanding the spider web of relationships among software components.

Why is Open Source ASM Important?

Open-source software is the backbone of modern enterprise technology stacks. By some estimates, upwards of 90% of commercial applications contain open-source components, and the average application contains hundreds of open-source libraries. This mass adoption has generated efficiencies and spurred innovation, but it has also significantly enlarged the attack surface that organizations need to protect.

The expanding attack surface

Open-source dependencies have serious implications in terms of security. The vulnerability tracked as Log4j (CVE-2021-44228) acted as a wake-up call for many organizations, impacting millions of devices and driving massive patching efforts globally. Correlatively, incidents such as the event-stream npm package compromission showcase how actors with malicious intent can utilize the popularity of open-source libraries as the vector for supply chain attacks against downstream users.

The visibility challenge

Most organizations do not have broad visibility of their open-source impact. Often, development teams introduce new dependencies without security review, which leads to the creation of so-called “shadow dependencies” with the security team unaware. This poor visibility results in vulnerabilities going unaddressed long after fixes have been made available, exposing organizations to easily avoidable attacks.

Regulatory and compliance pressures

Regulatory frameworks demand organizations increasingly maintain accurate software components inventories and fix known vulnerabilities quickly. From GDPR to sector-specific regulations like PCI DSS, compliance requires healthy open-source management practices that fit perfectly with Open Source ASM principles.

Key Components of Open Source Attack Surface Management

A structured approach is required for effective open-source ASM that uses technology and processes and infuses them into the organization. The key components enable organizations to work smart to discover, prioritize, and remediate risks from open-source dependencies.

Software inventory

Open Source ASM begins with a potentially complete and accurate list of all software assets. That involves keeping detailed Software Bills of Materials (SBOMs), which detail every open-source component employed, its version, licensing information, and provenance. Standardized formats, such as CycloneDX and SPDX, allow developers to describe these dependencies in an independent way, making them more visible, easier to analyze, and easier to share with other parties.

Continuous vulnerability monitoring

Regularly scanning codebases and comparing them against vulnerability databases such as the National Vulnerability Database (NVD), GitHub Security Advisories, and language-specific vulnerability feeds. Monitoring for CVEs is insufficient, it must correlate vulnerabilities to how an organization is actually using systems to determine what is truly exploitable.

Risk-based prioritization framework

Aware that not all vulnerabilities are created equal, they need to be prioritized in order to allocate resources effectively. The prioritization should be based on many aspects, i.e., vulnerability in degrees (CVSS scores), exploitability in the environment, how accessible the vulnerable component is, overall business impact, or mitigation available.

Seamless integration with development pipelines

Integrating Open Source ASM into the CI/CD pipeline changes ASM from a periodic manual activity into an automated, continuous process. Checking for vulnerable dependencies with pre-commit hooks, scans during automated build time, and container image analysis prevents bad dependencies from ever reaching production.

Remediation & mitigation strategies

Clearly defined remediation workflows are also part of an ecosystem for dealing with found vulnerabilities. Remediation strategies would consist of upgrading to patched versions, applying virtual patching solutions (WAF or RASP), using alternative components, or applying compensating controls when a patch is not available.

Common Threats Addressed by Open Source ASM

Open-source attack surface management evaluates threats across a diverse range of security vulnerabilities that target or leverage open-source components. By understanding these threats, organizations will be better able to implement countermeasures.

Exploitation of known vulnerabilities

As a path of least resistance into otherwise well-protected systems, attackers often target known vulnerabilities in popular open-source components. The ongoing risk was highlighted in the 2017 Equifax breach in which attackers took advantage of a known but unpatched vulnerability in Apache Struts that had been patched for months but not rolled out to Equifax’s systems. The same pattern continues across industries, as common open-source vulnerabilities such as Log4j, Spring4Shell, and OpenSSL become prime targets for attackers due to their implementational scale.

Supply chain compromises

The software supply chain is a top target for sophisticated attackers because they can hit multiple victims with a single attack vector. The SolarWinds incidents proved the damage such attacks can do, while smaller incidents, such as the manipulation of the event-stream npm package, proved that attackers are starting to zero in on open-source packages used by their targeted victims. Other types of such attacks rely on code being injected into legitimate packages or repositories, build server compromise, or developer account hijacking.

Dependency confusion attacks

Dependency confusion is a type of supply chain attack that exploits the behavior of package managers when they encounter naming collisions between public and private repositories. Attackers are able to register public packages that have names that are identical to an organization’s internal packages, and the build systems will automatically pull the public version, the malicious version. This attack vector started garnering attention back in 2021 when researcher Alex Birsan showed how effective it was against multiple large-volume organizations.

Abandoned package Risks

As open source projects grow, certain packages are no longer maintained or deprecated by their original developers. These “dead” dependencies pose a major security risk because they no longer receive security updates or bug fixes, so any newly discovered exploit leaves organizations open to attack. In some cases, bad actors have taken over abandoned packages to inject malware.

License compliance violations

License compliance issues are not exactly security threats, but they can represent major legal and financial threats to open-source software users. Some licenses come with requirements that may contradict an organization’s profit model or intellectual property strategy. Unfortunately, the unintended inclusion of code that is packaged under an incompatible license can expose a business to claims of copyright infringement, compelled disclosure of the code in its production software chain, and costly remediation efforts.

Challenges in Open Source ASM

Open-source ASM poses many challenges for organizations that are implementing it. With the continued acceleration of open-source component usage, security teams need to find a way to address these challenges to protect their organization from vulnerabilities that can lead to data breaches and a disruption of services that can lead to financial losses or regulatory fines.

Complexity of dependencies

Modern applications have deeply nested dependency structures where a single application may be dependent on hundreds or thousands of direct and transitive dependencies. This creates a “dependency pool” wherein security teams can no longer tell what their software is made of. These layers create a complex web of relationships, and an accurate understanding of the implications of vulnerabilities throughout an organization is very challenging; a critical vulnerability in a hyper-technical third or fourth-level dependency could cascade through many systems in the organization.

Limited overall visibility

Most organizations do not have a complete software bill of materials (SBOM), so you cannot identify all open-source components being used across their environment. The visibility gap is only increasing due to decentralized development practices, shadow IT, and the DevOps tendency to increase the pace of software deployment. Components can be added from a variety of sources, package managers, container images, copied from a web page, or software provided by vendors, resulting in blind spots in security monitoring.

Lack of resources and technical constraints

Implementing effective open-source ASM requires specialized tools and skilled personnel, both of which may be in short supply. Many organizations lack dedicated resources for managing open-source security, and instead, they distribute responsibility across already-strained development and security teams. The technical challenges of scanning containerized applications, serverless functions, and dynamically compiled code further complicate detection efforts.

Integration with development workflows

Retrofitting security practices into established development workflows creates friction that can impede the adoption of open-source ASM. Developers focused on feature delivery may resist additional security gates that slow down their release cycles or require a rework of existing implementations. Traditional security tools often generate high volumes of findings without context, leading to alert fatigue and diminished effectiveness.

Top Open Source Tools for Attack Surface Management

Open-source attack surface management is underpinned by a plethora of tools that assist organizations in discovering, monitoring, and addressing vulnerabilities in their open-source components.

CrowdStrike Falcon

CrowdStrike Falcon extends beyond its core endpoint protection capabilities to offer robust features for managing open-source security risks. The platform’s application security module provides continuous scanning of development environments to identify vulnerable open-source components early in the development lifecycle.

RiskIQ

Now part of Microsoft, RiskIQ offers powerful attack surface discovery capabilities that help organizations identify their external-facing assets, including those relying on vulnerable open-source components. The platform’s Internet Intelligence Graph maps an organization’s internet-exposed infrastructure, detecting outdated systems, misconfigured services, and applications running known vulnerable components. RiskIQ excels at discovering shadow IT and forgotten assets that often escape internal inventories but remain accessible to attackers.

Palo Alto Xpanse

Xpanse provides comprehensive external attack surface management with specialized capabilities for open-source vulnerability detection. The platform continuously monitors internet-exposed assets to identify systems running vulnerable open-source software, from web servers and applications to network services and IoT devices. Xpanse’s strength lies in its ability to discover unknown or forgotten assets across cloud providers, subsidiaries, and recently acquired companies, places where vulnerable open-source components often hide.

Nuclei Cloud

Nuclei Cloud leverages the popular open-source Nuclei vulnerability scanner to provide continuous monitoring of an organization’s external attack surface for vulnerable open-source components. The platform uses template-based scanning to detect specific vulnerability patterns across web applications, APIs, and infrastructure components. What makes Nuclei particularly valuable for open-source ASM is its extensive template library that includes checks for common open-source vulnerabilities and its community-driven approach that ensures rapid coverage for newly discovered issues.

Best Practices for Open Source ASM

The best practices listed below will help organizations create a sound open-source ASM program that balances risk reduction with innovation..

Categorize based on risk

Go beyond raw CVSS scores by creating a standard approach to vulnerability prioritization. Take into account things like: Is the vulnerable functionality actually used? Is the component directly accessible to external users? Is data processed by the component sensitive? Are compensating controls in place? Create documentation for this framework and enforce similar application throughout all teams. The good news is that automated tools can automatically enrich vulnerability data with context-specific risk information.

Embed security in developer processes

Integrate open source ASM into current developer tools and practices to make security a natural extension of the development process. You can do this in various ways, like by building IDE plugins that inform developers about vulnerable components as they are writing the code. Use build systems to automatically check dependencies before packaging applications. Formulate concise remediation guidance that allows developers to fix them quickly without needing to be security specialists themselves.

Governance policies and standards

Establish formal open-source usage policies that map risk tolerances to acceptable licenses and minimum maintainer requirements for dependencies. Apply these policies to automate checks in the CI/CD pipeline through technical controls. Form a governance committee that includes security, legal, and development representatives and that manages exceptions and policy evolution. These governance frameworks allow for a common risk management approach across the entire organization while also granting flexibility for business-critical applications through a well-documented exceptions process.

Invest in automating vulnerability remediation

Minimize human involvement in the remediation process to streamline the response to discovered weaknesses. Where permitted, the tools can create pull requests that reactively update vulnerable dependencies with safe alternatives. Have templates for common remediation patterns to enable developers to find the quickest fix for different types of vulnerabilities. Implementing automated tests to ensure that new changes do not break existing features.

Track the dependency supply chain

Take a wider view to evaluate the security posture of your open-source supply chain. Asses your dependencies on a per package basis based on maintainer activity, the quality of the code, the security of the code, and the community support. Stay alert for strange activity in dependency repositories, such as the addition of new maintainers, unusual commit patterns, or surprise changes to permissions that could reveal compromise. Download packages securely, verifying their integrity using checksums or signatures.

Introducing SentinelOne for Attack Surface Management

As cyber threats continue to evolve, SentinelOne has become one of the leading solutions for end-to-end attack surface management. Through its platform, SentinelOne offers organizations a single pane of glass that provides visibility and insight throughout their digital footprint.

Across cloud environments, on-premises infrastructure, endpoints, and IoT devices, the solution automatically finds and inventories assets, including ones with open source components. Such organization-wide visibility is key to identifying where vulnerable open-source components might be hiding in the organization. With its Singularity platform, SentinelOne correlates activity across silos, and stitches together a comprehensive view of the attack surface where potential exploits might be hiding, eliminating the blind spots where vulnerable dependencies might exist.

What sets SentinelOne apart from the competition is its real-time vulnerability detection and prioritization. It regularly checks for new vulnerability disclosures related to your detected open-source components and instantly correlates those with your environment. Instead of running point-in-time scans, SentinelOne provides persistent monitoring, alerting security teams as soon as a new vulnerability affects their environment. This time-based intelligence empowers organizations to substantially decrease their mean time to remediate (MTTR) for critical open-source vulnerabilities.

Conclusion

Open-source attack surface management is a significant development in the adoption of security practices by modern organizations. With businesses relying more and more on open-source components to help speed innovation and reduce development times, they also need to contend with the unique security challenges those dependencies raise. The right Open Source ASM with visibility, monitoring, and remediation capabilities allows development velocity to be balanced with the need to manage these risks.

The threats saga of open-source ASM, from exploitation of known vulnerabilities to supply chain attacks, illustrates why this discipline has become a must-have to ensure mature security programs. However, organizations that adopt strong open-source ASM practices drastically shrink their attack surface and time to exposure to new vulnerabilities and create more opportunity for resiliency against new threats.