Security First
Prevent vulnerabilities before they happen by forcing early security framing and secure-by-default design patterns.
Free
Works with the AI tools you already use
security-first
Example session with this skill installed
I need to implement a new file upload feature for our S3 bucket. Users will authenticate via JWT. Can you help me plan the implementation?
- Read your context and instructions
- Compiled the security-first
Trust Boundary: User-provided JWT vs S3 Bucket.
Assumptions: We assume the 'org_id' in the token is verified by the gateway.
Risk: Path traversal in file uploads.
Design: Using UUIDs for storage; enforcing internal-only ACLs.
Verification: Unit test with '../' in filename must fail.
Connects securely to your tools. The creator never sees your data.
About this skill
What it does
Security First is a preventive guardrail designed to bake security into the development lifecycle before the first line of code is even written. Instead of performing retrospective audits, this skill forces your AI agent to identify trust boundaries, surface security assumptions, and define verification steps during the planning phase.
Why use this skill
Standard LLMs often prioritize functionality over safety, frequently suggesting insecure defaults or overlooking edge cases like untrusted input and session handling. This skill shifts security "left" by requiring a structured analysis of the attack surface relevant to your specific task. It ensures that authentication, authorization, and data handling are treated as first-class requirements rather than afterthoughts.
Supported workflows
- Trust Boundary Mapping: Identifies actors, privileges, and sensitive data flows.
- Secure Defaults: Enforces the principle of least privilege and minimum secure design.
- Attack Surface Reduction: Evaluates webhooks, file storage, and infrastructure exposure.
- Pre-implementation Verification: Defines the exact tests needed to prove security properties.
The Output
The result is a concise, actionable security brief tailored to your current task. It avoids generic OWASP dumps in favor of specific risks, explicit assumptions, and a concrete verification plan to guide the coding process.
How to install
Works the same in every agent - Claude, Cursor, Codex, Copilot and 20+ more.
- 1
Download the ZIP
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- 2
Unzip into your skills folder
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- 3
Ask your agent to use it
Restart the agent if it was already running. It picks the skill up automatically - no config needed.
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Click the path to copy it. Create the folder if it does not exist yet.
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