Counter third-party risk with continuous vendor monitoring

Third-party risk has quietly become one of the largest and least-predictable attack surfaces. Organizations today rely on hundreds or thousands of vendors for cloud services, software, data processing, logistics and operations, yet many security programs still assess vendor risk once a year using static questionnaires. That model no longer matches the modern threat landscape. 

Recent real-world incidents have made the limitations of point-in-time vendor assessments painfully clear. In the 2023 MOVEit file transfer compromise, for example, a single vulnerability in a widely used third-party platform led to mass data breaches across hundreds of organizations, including financial institutions, healthcare providers and government agencies. Many affected customers had previously approved the vendor through standard risk reviews, but none had real-time visibility into emerging vulnerabilities, exploit activity or downstream exposure. 

This pattern repeats across supply chain attacks, SaaS misconfigurations, breached credentials and ransomware events. Plus, organizations change vendors routinely. And infrastructure evolves, security controls drift, new subcontractors are added and attackers move faster than annual reviews. 

It's time to consider continuous vendor monitoring, which helps close the gap by shifting third-party risk management from a compliance exercise to an operational security control. 

What to look for in continuous vendor monitoring 

Not all continuous vendor monitoring products are created equal. Security teams should focus on capabilities that provide signals, not noise. 

Look specifically for capabilities that deliver the following: 

• External attack surface intelligence. Continuous visibility into a vendor's exposed assets, vulnerabilities, misconfigurations and known exploit activity, without relying solely on vendor self-reporting. 

• Breach and incident monitoring. Detection of public breach disclosures, ransomware claims, leaked credentials and dark web activity tied to vendors or their infrastructure. 

• Security posture indicators. Ongoing assessment of factors such as patch hygiene, encryption practices, email security posture, certificate management and DNS hygiene. 

• Fourth-party risk awareness. Insight into critical subcontractors and dependencies, especially for SaaS and MSPs, where risk cascades quickly. This becomes even more critical with the use of AI applications and services. 

• Risk scoring with context. Scores should be explainable, trend-based and adjustable -- not numbers that can't support decision-making. 

• Integration into security workflows. APIs, SIEM and security orchestration, automation and response integration, ticketing hooks and governance, risk and compliance alignment are essential to translate findings into action. 

Challenges in continuous vendor monitoring 

Despite their promise, continuous vendor monitoring platforms introduce challenges that security teams must plan for, including the following: 

• Alert fatigue and false positives. External scanning can generate large volumes of findings that lack business context. Without tuning and prioritization, teams might end up ignoring the tool. 

• Misalignment with procurement and legal. Security teams might detect risk signals that procurement or legal teams are unprepared to act on, especially if contracts lack right-to-audit or remediation clauses. 

• Overreliance on scores. Treating risk scores as absolute truth can lead to poor decisions. Scores should inform risk discussions, not replace them. 

• Coverage gaps. Smaller vendors, niche SaaS providers or private infrastructure can be difficult to monitor externally, requiring compensating controls or direct engagement. 

• Ownership ambiguity. Without clear accountability, alerts can fall between security, vendor management and business owners. 

Future of continuous vendor monitoring 

Continuous vendor monitoring will increasingly merge with broader exposure management and identity-risk programs. Expect tighter integration with attack surface management, SaaS security posture management and nonhuman identity governance. Regulators and auditors will also raise expectations, shifting from "Did you assess the vendor?" to "How quickly did you detect and respond to vendor risk?" 

Perhaps most importantly, third-party risk will become a board-level resilience issue and not just a security concern. Organizations that treat vendor monitoring as a living, operational capability will be better positioned to absorb inevitable supply chain incidents without cascading business impact. In today's environment, continuous vendor monitoring is no longer about predicting every breach, it's about shortening the time between vendor failure and organizational response. 

Dave Shackleford is founder and principal consultant at Voodoo Security, as well as a SANS analyst, instructor and course author, and GIAC technical director.