Your Supply Chain Is an Attack Surface – Here’s How to Secure It

Supply chains are a favorite target for attackers. Every vendor, partner, and service provider adds new ways into your sensitive systems – many of which traditional defenses never catch. And criminals don’t need CVEs to break through. They find exposures that aren’t in any database and use them to move across connected systems. That’s why patching alone can’t keep up. Protecting critical assets means looking at your environment the way an attacker would – through both your own systems and the external surfaces of your suppliers.

In this blog, I’ll discuss how exposure management changes the game for supply chain security, the role of EASM and threat intelligence, and the practical steps companies can take to secure their supplier relationships.

Why Current Approaches Miss Supply Chain Risk

Traditional vulnerability management creates a critical gap: it scans internal environments…and essentially ignores the external attack surfaces where supply chain compromises begin. And even the internal scan data is sometimes incomplete, often lacking essential elements needed for proper prioritization of remediation, such as interconnections between exposure types.

Security teams are used to monitoring their own networks and applications comprehensively. What they’re not used to looking for is the supplier connections that create the most dangerous exposures – partner portals with weak authentication, vendor management interfaces exposed to the internet, monitoring tools with excessive privileges. These supplier surfaces can easily become the pathways that attackers use to move from compromised vendors into customer environments.

Standard EASM implementations fall short of addressing this challenge. True, they provide external visibility into supplier security posture through direct scanning and monitoring. Yet most platforms aggregate EASM data from third-party vendors rather than integrating it with internal risk context. They generate separate vulnerability reports without showing the complete attack path from external supplier exposures through your environment to critical assets. This means you get disconnected findings rather than a unified attack scenario analysis.

Supply Chain Attacks Bypass Traditional Defenses

This structural weakness explains why recent supply chain attacks have proven so deadly.

The attacks against SolarWinds, Kaseya, and Okta share a common thread: criminals bypassed CVE-based defenses entirely by exploiting supply chain relationships. SolarWinds involved infiltration of the software build process which then delivered malicious updates to thousands of downstream customers. Kaseya attackers compromised the managed service provider platform to reach its clients. Okta’s breach exposed the identity infrastructure that multiple organizations relied upon.

These attacks all succeeded because they targeted the supply chain’s most privileged connection points – the monitoring platforms that oversee customer networks, the management tools that control client systems, the identity providers that authenticate access across organizations. By compromising just one of these points, attackers gained access to hundreds of downstream victims.

Supply chain attackers have learned to exploit the trusted connections between organizations – the vendor integrations that have become mission critical to the way most businesses run. To achieve supply chain security, you need visibility into how these supplier relationships could become attack vectors. To do this, you need to connect technical discovery with the business relationships that can actually drive change.

Establishing a strong third-party risk management (TPRM) governance capability is crucial for an effective supply chain risk program. This involves classifying vendors based on their business dependence and potential impact, which helps prioritize risk management efforts. For instance, a critical supplier of raw materials would receive a higher classification than a non-essential service provider. A robust governance framework must also include documented processes for remediation to address non-compliance and a clear, auditable off-boarding process for when a vendor relationship is terminated. 

Building Supply Chain Defense: The Four-Pillar Framework

External Attack Surface Management (EASM): As discussed, the first pillar of supply chain security is EASM. Organizations use EASM tools to continuously scan third-party external surfaces and identify exposures in real time – misconfigured services, exposed credentials, shadow IT assets, and operational weaknesses that traditional vendor questionnaires miss entirely.

Effective Third-Party Remediation: The second pillar uses technical findings from EASM as the beginnings of business conversations that drive change. When EASM reveals significant exposures at a supplier, security teams need to engage relationship managers to push for remediation. The conversation shifts from “we trust you’re handling security properly” to “here’s exactly what’s broken and how you need to fix it.”

Vendor Leverage and Governance: The effectiveness of these conversations depends on the third pillar: business leverage and organizational structure. Companies with major vendor dependencies can demand security improvements through purchasing power and contract requirements. Smaller organizations face the constraints of limited staff and negotiating power – but can still rely on contract language and technical controls like network segmentation.

Threat Intelligence and Prioritization: The fourth pillar is current threat intelligence about how attackers actually exploit supplier weaknesses. Understanding current attacker TTPs – the specific techniques cybercriminals use to compromise monitoring tools, management platforms, and identity providers – transforms EASM findings from generic vulnerability data into targeted threat scenarios. This creates focused remediation targets that reflect real attack scenarios rather than theoretical severity scores.

Together, these four pillars form a complete operational cycle: EASM discovers supplier exposures, threat intelligence prioritizes them based on current attacker techniques, and business relationships drive remediation across organizational boundaries.

Making Supply Chain Security Work

How do you put this four-pillar framework into practice? Start by deploying EASM tools to scan supplier external surfaces continuously. Establish clear escalation paths from your security team to third-party relationship managers who can drive those important vendor conversations. Build business leverage through contract requirements and vendor dependency assessments. Integrate threat intelligence feeds that reveal current attacker TTPs that are targeting supply chain relationships.

Focus on attack graph modeling rather than vulnerability scores for prioritization. Traditional platforms generate lists of individual weaknesses across disconnected systems – internal vulnerability scans here, EASM findings there, compliance reports elsewhere. Many platforms simply ingest data feeds from other EASM vendors and present them as separate findings rather than integrated attack scenarios. Effective supply chain security maps complete attack paths from supplier exposures to your critical assets. This shows which external vulnerabilities pose real risk to business operations because attackers could actually exploit them.

Measure what matters. Track time from exposure discovery to vendor engagement. Monitor supplier remediation rates. Assess reduction in viable attack paths over time. These metrics reveal whether your program creates real security improvements or just generates more reports.

The Bottom Line

Supply chain security succeeds when organizations can see supplier risks as they emerge and respond before attackers exploit them. The criminals already understand how your vendor relationships create opportunities. Your security program needs to understand these connections just as clearly – and act on that understanding faster than the attackers.