Snowflake Access Guardian

Snowflake Access Guardian

Overview

Turn a sanitized Snowflake authorization inventory into an evidence-backed effective-access trace and a dry-run remediation packet. This is the focused Snowflake counterpart to a generic RBAC explainer: it catches the failure modes that make enterprise reviews expensive—role inheritance that was not followed, direct user and PUBLIC grants, abandoned grantees, ownership control, managed access semantics, secondary-role assumptions, and future-grant precedence.

Prerequisites

• Receipted, sanitized outputs from the bundled historical, session, role, user, database-role, and relevant database/schema future-grant collectors.
• A named principal/object/privilege question, account/role identity, UTC collection timestamp, observation window, and explicit freshness bound. Live Snowflake checks remain the operator's responsibility.
• Timestamped positive (allowed action) and negative (denied action) receipts captured under the same primary/secondary-role context; missing proof is NOT_PROVEN, never an inferred denial.
• Python 3.10+ for the bundled stdlib analyzer. No Snowflake driver or network access is required.

Authentication

This skill's analyzer is offline and deliberately has no authentication flow. If live Snowflake evidence is collected, use the organization's approved Snowflake session/authentication process; never put its credentials in the inventory or report. Use Write only to save a sanitized report or approved local change packet; never to apply Snowflake mutations.

Safety contract

• Read-only by default. The analyzer does not connect to Snowflake and never executes GRANT, REVOKE, GRANT OWNERSHIP, ALTER USER, or policy changes.
• Accept sanitized metadata only. Do not provide passwords, tokens, private keys, raw connection strings, or access-history payloads containing sensitive data.
• Do not infer denial from a missing historical row. Account Usage can lag by up to 120 minutes and has documented object/shared-role omissions.
• Never broaden to ACCOUNTADMIN or automatically grant MANAGE GRANTS to get a more complete snapshot. MANAGE GRANTS can administer grants and is not a read-only privilege, even when this collector executes only SHOW statements.
• Do not infer that a role is unused from one telemetry source. Name the review period, object coverage, and evidence gaps.
• Treat ownership as control-plane authority and future OWNERSHIP as a separate high-risk decision. Never auto-generate executable mutation SQL.

Workflow

1. Establish the principal, target object, privilege, evidence timestamp, review period, and whether the question is about a primary-role or secondary-role session. Read authorization-model.md for path and evidence rules.

2. Collect the delayed account-wide baseline with a role holding Snowflake's SNOWFLAKE.SECURITY_VIEWER database role. Preserve the receipt unchanged:

   python3 "${CLAUDE_SKILL_DIR}/scripts/collect_snowflake_evidence.py" \
     --surface access --connection <existing-readonly-profile> \
     --output ./snowflake-access-historical.json

3. Collect current evidence only for the declared review scope. Capture the session context without changing roles, then collect grants to and grants of each account role, target-user roles, involved database roles, and paired database/schema future grants:

   python3 "${CLAUDE_SKILL_DIR}/scripts/collect_snowflake_evidence.py" \
     --surface access-session --connection <profile> --output ./session.json
   python3 "${CLAUDE_SKILL_DIR}/scripts/collect_snowflake_evidence.py" \
     --surface access-role-current --role DATA_READER \
     --connection <profile> --output ./role-current.json
   python3 "${CLAUDE_SKILL_DIR}/scripts/collect_snowflake_evidence.py" \
     --surface access-role-parents --role DATA_READER \
     --connection <profile> --output ./role-parents.json
   python3 "${CLAUDE_SKILL_DIR}/scripts/collect_snowflake_evidence.py" \
     --surface access-future-database --database ANALYTICS \
     --connection <profile> --output ./future-database.json
   python3 "${CLAUDE_SKILL_DIR}/scripts/collect_snowflake_evidence.py" \
     --surface access-future-schema --schema ANALYTICS.CURATED \
     --connection <profile> --output ./future-schema.json

   Selectors accept only supported one-part or two-part unquoted identifiers; quoted/multipart identifiers need a separately reviewed collection path. Each scoped SHOW uses one Snowflake pipe statement that emits both the allowlisted rows and its execution context. Invocations may use different physical sessions; the analyzer requires equivalent account, user, primary role, role type, and secondary-role state. Saved/offline access JSON is not accepted as current evidence. Read current-evidence-contract.md for every surface and the schema 2.0 bundle. Permission errors, missing declared selectors, a missing current PUBLIC role receipt, cap hits, or an unpaired schema receipt remain blockers.

4. At the controlled local collection boundary, assemble the bundle and record its canonical digest separately. Analyze the exact same bundle with that digest:

   python3 "${CLAUDE_SKILL_DIR}/scripts/analyze_access_evidence.py" \
     --input ./snowflake-access-bundle.json --print-input-sha256
   python3 "${CLAUDE_SKILL_DIR}/scripts/analyze_access_evidence.py" \
     --input ./snowflake-access-bundle.json \
     --trusted-input-sha256 sha256:<separately-recorded-digest> \
     --out ./snowflake-access-report.json

   The receipt analyzer validates templates, selectors, sources, row counts, caps, Snowflake observation timestamps, request-derived coverage, equivalent authorization contexts, and the bundle digest before invoking the graph analyzer. The matching digest is an operator assertion of byte identity, not authentication; computing it from an untrusted copy creates no trust. analyze_access.py remains a diagnostic path for legacy sanitized inventories, but it cannot establish receipted completeness.

5. For each finding, distinguish observed, not proven, and needs live verification. Resolve managed-access, ownership, and future-grant findings with managed-access-and-future-grants.md. The report must retain direct-user paths and every ownership path separately; ownership is control-plane authority, not routine access.

6. Produce a dry-run change packet: current path, intended path, exact proposed principal/privilege/object edge, approver, executor, precondition, reversal, and residual risk. Proposed SQL may be described as a review artifact, but it is not executed by this skill.

7. Require positive and negative verification before an authorized operator applies anything. Use verification-and-rollback.md for receipt fields and rollback boundary. When database- and schema-level future grants overlap, report effective schema precedence and test a disposable object; do not summarize the conflict as a generic duplicate.