Topic starter
06/01/2026 4:32 pm
TL;DR: Google Cloud uses different IAM permission representations for allow policies, deny policies, and audit logs, and only about 5,000 of roughly 12,000 grantable permissions have a V2 deny-policy form, according to Sonrai Security. That mismatch makes centralised denial harder to reason about and pushes cloud IAM teams to validate policy syntax, logging, and troubleshooting workflows together.
Editorial analysis by NHI Mgmt Group, based on content published by Sonrai Security: “Why GCP’s Two IAM APIs Matter More Than You Think”.
By the numbers:
- Nearly 2,000 Google-managed pre-defined roles are available for use, according to Sonrai Security research.
Key questions
Q: Where does GCP IAM deny policy enforcement fail in practice?
A: It fails wherever a permission has no IAM v2 representation, because deny policies can only reference the v2 form.
Q: Why do GCP IAM permission mismatches create operational risk for cloud teams?
A: Because the same action can show up as one string in allow policy work, another in deny policy text, and a third in audit logs.
Q: What are the signs that a GCP deny policy is not covering everything it should?
A: A common signal is that a permission is still grantable through a role binding but cannot be expressed in deny form, or that an error log shows a permission name developers cannot find in the policy file.
Practitioner guidance
- Audit V2 deny-policy coverage Inventory the permissions you rely on for central restriction and identify which ones still lack an IAM v2 representation.
- Build a permission translation map Create a controlled mapping between IAM v1 names in logs and IAM v2 names in deny policies so engineers can trace one permission across allow, deny, and audit workflows without manual guesswork.
- Test deny-policy troubleshooting end to end Validate whether teams can reproduce a denied action, inspect the log entry, and identify the exact deny policy without relying on ad hoc translation or tribal knowledge.
Bottom line: GCP IAM v1 and v2 use different permission representations, and that split makes deny-policy enforcement harder to reason about at scale.
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This topic was modified 2 days ago by NHI Mgmt Group
11/10/2026 3:31 am
Permission representation drift is now an authorization control issue. When allow policy syntax, deny policy syntax, and audit evidence all use different identifiers for the same underlying permission, governance teams lose a single authoritative view of effective access. That makes policy reasoning dependent on translation discipline rather than on policy intent alone. The practitioner conclusion is that representation consistency must be treated as part of access control design.
A few things that frame the scale:
- 92% of organisations expose NHIs to third parties, raising concerns about supply chain security, according to the Ultimate Guide to NHIs.
- 97% of NHIs carry excessive privileges, increasing unauthorised access and broadening the attack surface, according to the Ultimate Guide to NHIs.
A question worth separating out:
Q: How should teams investigate an access denial in GCP when the log and policy names do not match?
A: Start by translating the logged IAM v1 permission into the corresponding IAM v2 deny-policy form, then check whether the service even supports that v2 representation. If the mapping is inconsistent, the issue may be representation mismatch rather than a malformed rule.
👉 Read our full editorial: GCP IAM v1 and v2 permissions create hidden deny-policy gaps