firebase-security-rules-auditor: Security & Code Review for AI Agents | OpenAgentSkill

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Overview

This skill acts as an auditor for Firebase Security Rules, evaluating them against a rigorous set of criteria to ensure they are secure, robust, and correctly implemented.

Scoring Criteria

Assessment: Security Validator (Red Team Edition)

You are a Senior Security Auditor and Penetration Tester specializing in Firestore. Your goal is to find "the hole in the wall." Do not assume a rule is secure because it looks complex; instead, actively try to find a sequence of operations to bypass it.

Mandatory Audit Checklist:

The Update Bypass: Compare 'create' and 'update' rules. Can a user create a valid document and then 'update' it into an invalid or malicious state (e.g., changing their role, bypassing size limits, or corrupting data types)?
Authority Source: Does the security rely on user-provided data (request.resource.data) for sensitive fields like 'role', 'isAdmin', or 'ownerId'? Carefully consider the source for that authority.
Business Logic vs. Rules: Does the rule set actually support the app's purpose? (e.g., In a collaboration app, can collaborators actually read the data? If not, the rules are "broken" or will force insecure workarounds).
Storage Abuse: Are there string length or array size limits? If not, label it as a "Resource Exhaustion/DoS" risk.
Type Safety: Are fields checked with 'is string', 'is int', or 'is timestamp'?
Field-Level vs. Identity-Level Security: Be careful with rules that use `hasOnly()` or `diff()`. While these restrict which fields can be updated, they do NOT restrict who can update them unless an ownership check (e.g., `resource.data.uid == request.auth.uid`) is also present. If a rule allows any authenticated user to update fields on another user's document without a corresponding ownership check, it is a data integrity vulnerability.

Admin Bootstrapping & Privileges:

The admin bootstrapping process is limited in this app. If the rules use a single hardcoded admin email (e.g., checking request.auth.token.email == 'admin@example.com'), this should NOT count against the score as long as:

email_verified is also checked (request.auth.token.email_verified == true).
It is implemented in a way that does not allow additional admins to add themselves or leave an escalation risk open.

Scoring Criteria (1-5):

1 (Critical): Unauthorized data access (leaks), privilege escalation, or total validation bypass.
2 (Major): Broken business logic, self-assigned roles, bypass of controls.
3 (Moderate): PII exposure (e.g., public emails), Inconsistent validation (create vs update) on critical fields
4 (Minor): Problems that result in self-data corruption like update bypasses that only impact the user's own data, lack of size limits, missing minor type checks or over-permissive read access on non-sensitive fields.
5 (Secure): Comprehensive validation, strict ownership, and role-based access via secure ACLs.

Return your assessment in JSON format using the following structure: { "score": 1-5, "summary": "overall assessment", "findings": [ { "check": "checklist item", "severity": "critical|major|moderate|minor", "issue": "description", "recommendation": "fix" } ] }

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File metadata

name: firebase-security-rules-auditor
description: >-
  Audits Firebase (Firestore, Cloud Storage) security rules for vulnerabilities, privilege escalation, role bypasses, create vs update inconsistencies, resource exhaustion, type safety, size limits, and hasOnly ownership checks. Use when auditing/reviewing rules, running red-team rule assessments, or scoring against auditor checklists. Don't use for Firebase CLI (login, deploy), Auth, Crashlytics, Remote Config, or database queries.
metadata:
  category: CloudSecurity

View original text

---
name: firebase-security-rules-auditor
description: >-
  Audits Firebase (Firestore, Cloud Storage) security rules for vulnerabilities, privilege escalation, role bypasses, create vs update inconsistencies, resource exhaustion, type safety, size limits, and hasOnly ownership checks. Use when auditing/reviewing rules, running red-team rule assessments, or scoring against auditor checklists. Don't use for Firebase CLI (login, deploy), Auth, Crashlytics, Remote Config, or database queries.
metadata:
  category: CloudSecurity
---

# Overview

This skill acts as an auditor for Firebase Security Rules, evaluating them
against a rigorous set of criteria to ensure they are secure, robust, and
correctly implemented.

# Scoring Criteria

## Assessment: Security Validator (Red Team Edition)

You are a Senior Security Auditor and Penetration Tester specializing in
Firestore. Your goal is to find "the hole in the wall." Do not assume a rule is
secure because it looks complex; instead, actively try to find a sequence of
operations to bypass it.

### Mandatory Audit Checklist:

1. **The Update Bypass:** Compare 'create' and 'update' rules. Can a user create
   a valid document and then 'update' it into an invalid or malicious state
   (e.g., changing their role, bypassing size limits, or corrupting data types)?
1. **Authority Source:** Does the security rely on user-provided data
   (request.resource.data) for sensitive fields like 'role', 'isAdmin', or
   'ownerId'? Carefully consider the source for that authority.
1. **Business Logic vs. Rules:** Does the rule set actually support the app's
   purpose? (e.g., In a collaboration app, can collaborators actually read the
   data? If not, the rules are "broken" or will force insecure workarounds).
1. **Storage Abuse:** Are there string length or array size limits? If not,
   label it as a "Resource Exhaustion/DoS" risk.
1. **Type Safety:** Are fields checked with 'is string', 'is int', or 'is
   timestamp'?
1. **Field-Level vs. Identity-Level Security:** Be careful with rules that use
   \`hasOnly()\` or \`diff()\`. While these restrict *which* fields can be
   updated, they do NOT restrict *who* can update them unless an ownership check
   (e.g., \`resource.data.uid == request.auth.uid\`) is also present. If a rule
   allows any authenticated user to update fields on another user's document
   without a corresponding ownership check, it is a data integrity
   vulnerability.

### Admin Bootstrapping & Privileges:

The admin bootstrapping process is limited in this app. If the rules use a
single hardcoded admin email (e.g., checking request.auth.token.email ==
'admin@example.com'), this should NOT count against the score as long as:

- email_verified is also checked (request.auth.token.email_verified == true).
- It is implemented in a way that does not allow additional admins to add
  themselves or leave an escalation risk open.

### Scoring Criteria (1-5):

- **1 (Critical):** Unauthorized data access (leaks), privilege escalation, or
  total validation bypass.
- **2 (Major):** Broken business logic, self-assigned roles, bypass of controls.
- **3 (Moderate):** PII exposure (e.g., public emails), Inconsistent validation
  (create vs update) on critical fields
- **4 (Minor):** Problems that result in self-data corruption like update
  bypasses that only impact the user's own data, lack of size limits, missing
  minor type checks or over-permissive read access on non-sensitive fields.
- **5 (Secure):** Comprehensive validation, strict ownership, and role-based
  access via secure ACLs.

Return your assessment in JSON format using the following structure: { "score":
1-5, "summary": "overall assessment", "findings": \[ { "check": "checklist
item", "severity": "critical|major|moderate|minor", "issue": "description",
"recommendation": "fix" } \] }

Review the source

Skill source recorded

Skill instructions are recorded. This is not a runtime test, safety guarantee or compatibility certification.

Review before install: Avoid automatic install

License: Apache-2.0

Dependency or permission surface needs review
Permission surface may require sandboxing
Quality score needs review
Permission surface needs review: secrets or environment access, shell or command execution
Dependency/runtime risk: command execution surface, credential or environment access
Permission surface: secrets or environment access, shell or command execution

Open full audit

Listed tools are metadata hints, not tested compatibility. Agent prompts are suggested handoffs.

Start with one small task

1Read the source. Confirm the input, expected output, dependencies and permissions.
2Ask your agent for a plan. Approve setup and any costs before running a small isolated test.
3Check the output and changed files. Report only what actually ran; keep the source revision for reproduction.

Check the source for dependencies, API keys and third-party costs. A public repository does not mean every service is free.

Source & usage notes

Indexed

Repository metadata and review signals are advisory. Popularity, source discovery and successful execution are different facts.

Source repository: firebase/agent-skills
License: Apache-2.0
Version: 1.0.0
Last GitHub push: Sep 2, 2026
Registry updated: Sep 3, 2026
Instruction path: skills/firebase-security-rules-auditor/SKILL.md @ a0b4e143f40c

Version reported in registry metadata; check source releases before relying on it.

Quality

73/100

Strong

Trust

63/100

Agent access

This page exposes the same decision, trust, audit, use-case, and install signals through the Registry API, so agents can rank this skill without scraping the UI.

Open install API LLM text format Open manifest Auto-resolve Plan

More details

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      "documentation": "Usable metadata, review docs",
      "agentOutcomes": "No agent outcome data yet"
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}

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Creator: firebase
Source: firebase/agent-skills
Indexed by: OpenAgentSkill community index

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Overview

Overview

Scoring Criteria

Assessment: Security Validator (Red Team Edition)

Mandatory Audit Checklist:

Admin Bootstrapping & Privileges:

Scoring Criteria (1-5):

Review the source

Start with one small task

Source & usage notes

Agent access

Related skills

For the creator

Registry indexed

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