Third-Party Access Risks and Zero-Trust Mitigation Best Practices

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Third-party vendors are fast becoming the weakest link in enterprise security. Recent lawsuits against Adidas America and the University of Chicago Medical Center (UCMC), alongside a multimillion-dollar settlement involving AT&T, underscore a new reality: organizations are being held accountable not just for their own security, but for the failures of their vendors.

The point of breach in each case was not the company’s own infrastructure, but external service providers customer service centers, debt collectors, or cloud vendors. These incidents illustrate how third-party identity risks can cascade into operational disruption, legal liability, and reputational harm.

The 7 Types of Third-Party Access Risks

An analysis of recent high-profile cases reveals seven recurring categories of third-party identity security risks:

1. Unauthorized access – Example - Adidas vendor breach (2025) where compromised call-center credentials exposed customer PII.

2. Secrets exposure – Example - Sisense breach (2024) caused by leaked GitLab credentials granting access to cloud storage.

3. Over-privileged access – Example - Okta/Sitel breach (2022) where vendor admin rights enabled attackers to infiltrate core systems.

4. Lack of visibility and control – Example - SolarWinds attack (2020) highlighting how hidden supply-chain software risks can cascade across thousands of customers.

5. Compliance and regulatory risk – Example - UChicago Medical Center breach (2025) where weak vendor oversight led to HIPAA violations.

6. Supply-chain and cascading breaches – Example - Target HVAC breach (2013) where a minor vendor compromise caused a massive retail breach.

7. Privilege abuse / insider action – Example - Blackbaud ransomware breach (2020) where attackers exploited privileged vendor accounts to steal data.

These cases map directly to NIST CSF 2.0 “ID.SC” supply-chain controls and ISO 27001:2022 Annex A third-party clauses, showing how governance failures around credentials, entitlements, and oversight translate into systemic risk.

Zero Trust Mitigation:  Best Practices

To reduce exposure, organizations must assume third-party identities are already compromised and enforce continuous verification.

• Limit and Monitor Access – Apply least privilege, time-bound entitlements, and access recertification.

• Strong IAM Controls – Require MFA, enforce RBAC, and protect sensitive access with Privileged Access Management (PAM).

• Zero Trust Principles – Validate every vendor request; segment access to prevent lateral movement.

• Due Diligence and Continuous Oversight – Vet vendors upfront, then monitor compliance and behavior continuously.

• Risk-Based Vendor Prioritization – Focus the tightest controls on vendors with the most sensitive data exposure.

• Unified Visibility – Maintain an up-to-date inventory of vendor accounts, credentials, and entitlements across SaaS, cloud, and on-prem systems.

The Unosecur Advantage

Unosecur addresses third-party access governance with:

• Unified Identity Fabric – Maps every vendor, human, and machine identity across AWS, Azure, GCP, SaaS, and AD in minutes.

• Just-in-Time (JIT) Access – MFA-gated, auto-expiring entitlements for contractors and suppliers, fully session-recorded.

• Real-Time ITDR – Behavioral analytics mapped to MITRE ATT&CK detect lateral-movement tactics and instantly revoke risky sessions.

• Automated Entitlement Reviews – Rightsizing and pruning of vendor privileges runs continuously in the background.

• Audit-Ready Reporting – One-click evidence for ISO 27001, SOC 2, GDPR, and HIPAA.

This shifts third-party governance from manual and reactive to continuous and automated, delivering measurable assurance to both security teams and regulators.

Bottom Line

Third-party breaches are no longer “somebody else’s problem.” Courts, regulators, and customers are holding primary organizations accountable. By implementing Zero Trust identity practices, enforcing least privilege, and continuously monitoring vendor activity, companies can transform third-party access from a blind spot into a managed, auditable, and defensible part of their security posture.