How should security teams detect transitive access to sensitive cloud resources in Google Cloud?

Why This Matters for Security Teams

In Google Cloud, sensitive resource exposure is often not about a single broad role, but about who can reach a service account, who can impersonate it, and what that service account can touch once used. That makes transitive access a higher-risk problem than direct IAM review suggests. The practical concern is not just entitlement sprawl, but hidden paths that turn ordinary identities into effective administrators. The OWASP Non-Human Identity Top 10 treats over-privileged non-human identities as a recurring failure mode, and NHIMG research shows how often teams discover these issues only after exposure has already spread.

Security teams also need to account for delegated trust in adjacent systems. A human, group, workload, or external principal may not have direct access to a bucket, dataset, or project, but may still be able to act as the service account that does. That is why cloud IAM review must extend beyond direct bindings into impersonation chains, inherited permissions, and service account delegation. NHIMG’s Ultimate Guide to NHIs — Key Challenges and Risks is useful here because it frames the identity layer as the control plane, not just the credential store. In practice, many security teams encounter transitive access only after a post-incident review, rather than through intentional entitlement analysis.

How It Works in Practice

The most reliable approach is to map access as a graph, not as a static list. Start with the target resource, then identify every direct IAM binding and every inherited binding from folder or organization scope. In Google Cloud, that means tracing principals that can read, write, administer, or set policy on the resource, then asking one more question for each principal: can it impersonate a service account that has broader rights?

From there, enumerate service accounts and resolve their effective permissions. Use Policy Analyzer and Cloud Asset Inventory to find which identities can act as a service account, including users, groups, other service accounts, and workload identities. Then inspect chained impersonation. A user may not be able to reach the resource directly, but may be able to impersonate service account A, which can impersonate service account B, which can finally access the sensitive dataset or secret. That pattern is a classic NHI issue, and the NHI Lifecycle Management Guide is relevant because service account trust should be reviewed across creation, delegation, rotation, and decommissioning.

• Review direct IAM bindings on the resource first, then move upward through project, folder, and organization inheritance.
• Identify every principal with service account impersonation capability.
• Check whether groups or workforce identities can indirectly reach the same service account.
• Repeat until the path ends or reaches an external trust boundary.

For governance, align the findings with NIST SP 800-53 Rev 5 Security and Privacy Controls and use NIST Cybersecurity Framework 2.0 to structure discovery, analysis, and response. These controls tend to break down when organisations have many nested projects and permissive service account delegation because the impersonation graph becomes too large to review manually.

Common Variations and Edge Cases

Tighter transitive-access review often increases operational overhead, requiring organisations to balance coverage against change velocity. That tradeoff matters in Google Cloud because some environments rely heavily on automation, short-lived pipelines, and cross-project service accounts.

One common edge case is workload-to-workload access in CI/CD. A pipeline service account may not have direct resource rights, but it can mint tokens, call other APIs, and chain into another identity with broader permissions. Another is group membership drift, where a user joins a group that can impersonate a service account long after the original access review. Current guidance suggests treating these as identity-path problems, not just IAM-policy problems, but there is no universal standard for this yet. Teams should therefore combine policy analysis with event logging and periodic graph review.

High-value resources also require special attention when permissions are inherited through organization policies or when external identities are involved. The Top 10 NHI Issues research is a useful reminder that over-privilege and poor lifecycle control usually travel together. For implementation discipline, the OWASP view is reinforced by the OWASP Non-Human Identity Top 10, especially where service accounts are reused across environments. In practice, transitive access review is hardest when impersonation is enabled broadly and resource ownership is fragmented across many teams.

Related resources from NHI Mgmt Group

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• How should security teams implement policy-based access controls for ERP systems that contain sensitive personal and financial data?
• How should security teams govern access when users can bind the organisation to a cloud security service agreement?
• How should security teams manage privileged access in SAP S/4HANA environments that span on premises, cloud, and hybrid deployments?