aws-iam

Cross-account AccessDenied errors occur when trust policies, permission policies, or resource-based policies lack the required principal access for STS assume-role flows. This analysis maps the failing action to the exact missing authorization across identity, resource, and session policy layers.

An Organizations SCP acts as a guardrail through explicit deny precedence during AWS IAM policy evaluation. If an SCP denies an action, it overrides all identity-based, resource-based, and permission boundary policies, blocking authorization regardless of allowed permissions.

AWS IAM kms:* permissions fail when the KMS key policy or grant constraints restrict access. This debugging isolates the failing layer by checking KMS key policies and grants separately from IAM identity-based policies to find the minimum missing authorization.

Debug AWS IAM AccessDenied errors by applying an explicit-deny-first analysis across identity-based, resource-based, permission boundary, session policy, SCP, and KMS key policy layers. This isolates the exact principal, action, resource, and policy-layer causing the authorization failure.

Design cross-account STS assume-role authorization by mapping the required principal, action, and resource across trust and permission policies. This ensures correct AWS IAM access by validating both the trusting and trusting account policy relationships.

Permission boundaries override AWS IAM identity-based policies when the boundary restricts actions that the identity policy allows. The effective permissions are the intersection of the boundary and identity policy, combined with explicit deny checks from SCPs and resource policies.