security-and-hardening

security-and-hardening is a skill for Claude Code, Cursor from mamahoos/dot-files. It costs 113 tokens per session (6,393 once invoked), scanned B, a copy of security-and-hardening, MIT.

A security guide for software that accepts outside data, manages accounts, stores sensitive information, or connects to other services. It treats inputs as untrusted and requires deliberate checks around access and secrets.

In plain words
What is it for?
Use it to threat-model and harden features involving user input, login sessions, file uploads, webhooks, external APIs, payments, or personal data.
Why use it?
It helps expose and reduce vulnerabilities before attackers can exploit weak input handling, authentication, authorization, or data protection.

Skill for Claude CodeCursor

Written for Claude Code and Cursor: disable-model-invocation in frontmatter, but also installed under .cursor/. Also seen: positional $N argument.

Good fit Use it to threat-model and harden features involving user input, login sessions, file uploads, webhooks, external APIs, payments, or personal data.

Compare 6 skills from other repositories ↓
Install with agentmods
npx agentmods add skills/mamahoos/dot-files/security-and-hardening
Install

Getting it into your agent

One page per mod, every tool's command on it. A separate URL per tool would split the same page into five that compete with each other.

Any agent
npx skills add mamahoos/dot-files --skill security-and-hardening
Clone the repo
git clone --depth 1 https://github.com/mamahoos/dot-files

Made for: Claude Code, Cursor.

Wrote this? Show the measurements

A badge with what this costs and how it scanned, read live from this page, so it follows the numbers instead of freezing them. Markdown for a README, HTML for a documentation site or a project page.

agentmods badge for security-and-hardening

README.md
[![agentmods](https://agentmods.dev/badge/skills/mamahoos/dot-files/security-and-hardening/github.svg)](https://agentmods.dev/skills/mamahoos/dot-files/security-and-hardening)
Your own site
<a href="https://agentmods.dev/skills/mamahoos/dot-files/security-and-hardening"><img src="https://agentmods.dev/badge/skills/mamahoos/dot-files/security-and-hardening/github.svg" alt="Measured on agentmods" height="20"></a>

Or the 80×15 button, for a site that already has a row of RSS and ATOM ones. Only the verdict fits; the numbers stay here.

agentmods 80×15 button for security-and-hardening

Your own site · 80×15
<a href="https://agentmods.dev/skills/mamahoos/dot-files/security-and-hardening"><img src="https://agentmods.dev/badge/skills/mamahoos/dot-files/security-and-hardening.svg" alt="Reviewed on agentmods" width="80" height="20"></a>
Per session 113 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 6,393 The whole file, excluding the scripts and references it only reads on demand.
Security scan B 2 findings. A grade says what 26 rules found in the file — not that it is safe.
Origin 100% copy Near-identical to another mod in the catalogue.
Token cost

What it costs to keep this loaded

Counted locally with the o200k_base tokenizer, which is exact for GPT models; Claude uses its own tokenizer and its counts differ. Treat this as one consistent yardstick across the catalogue rather than a bill. Prices are per million input tokens.

ModelPer sessionOnce invoked
Fable 5.1 $0.00113 $0.06393
Opus 5 $0.00056 $0.03197
Sonnet 5 $0.00023 $0.01279
Haiku 4.5 $0.00011 $0.00639

Measured today against content hash c2129d14d7aa, method: parsed. Prices are Anthropic first-party input rates as of 2026-09-09, from the pricing page.

Security

Grade B, and why

security-and-hardening scanned grade B with 2 findings against 26 rules in 11 categories — prompt injection, anti-refusal, data exfiltration, privilege escalation, supply chain, agent snooping, system-prompt leakage, SSRF and excessive agency — measured today.

A static scan of the body, not an audit. Every finding is printed with the line that produced it so you can judge whether it matters here. A mod is markdown that instructs an agent; that is exactly why what it instructs is worth reading.

Cloud metadata endpointmediumServer-side request forgery

One request to 169.254.169.254 can return temporary IAM credentials.

The `range() !== 'unicast'` check covers loopback, link-local `169.254.169.254` (cloud metadata, the #1 SSRF target), private, and unique-local ranges across IPv4 and IPv6.

Downgraded: this mod is about security review, or the phrase is quoted, so it is likely naming the pattern rather than instructing it.

Makes network callslowCapability

Not a fault in itself. Listed so you know the mod talks to something, and to what.

await fetch(req.body.webhookUrl);
Origin

This is a copy

100% identical to security-and-hardening — 1 line differ, which has more behind it and is treated as the original. This page carries a canonical link to it rather than competing with it.

home/.cursor/skills/security-and-hardening/SKILL.md · 526 lines

How it starts

The opening of the file, as written. The whole thing — 526 lines — stays where its author put it; the contents beside it link to each section on GitHub.

Security and Hardening

Overview

Security-first development practices for web applications. Treat every external input as hostile, every secret as sacred, and every authorization check as mandatory. Security isn't a phase — it's a constraint on every line of code that touches user data, authentication, or external systems.

When to Use

  • Building anything that accepts user input
  • Implementing authentication or authorization
  • Storing or transmitting sensitive data
  • Integrating with external APIs or services
  • Adding file uploads, webhooks, or callbacks
  • Handling payment or PII data

Process: Threat Model First

Controls bolted on without a threat model are guesses. Before hardening, spend five minutes thinking like an attacker:

  1. Map the trust boundaries. Where does untrusted data cross into your system? HTTP requests, form fields, file uploads, webhooks, third-party APIs, message queues, and LLM output — plus the local values that look internal because the OS handed them to you: another process's command line or environment, filenames on a shared volume, a path in a job payload. Trust follows who wrote a value, not which channel delivered it. Every boundary is attack surface.
  2. Name the assets. What's worth stealing or breaking? Credentials, PII, payment data, admin actions, money movement.
  3. Run STRIDE over each boundary — a quick lens, not a ceremony:
Threat Ask Typical mitigation
Spoofing Can someone impersonate a user/service? Authentication, signature verification
Tampering Can data be altered in transit or at rest? Integrity checks, parameterized queries, HTTPS
Repudiation Can an action be denied later? Audit logging of security events
Information disclosure Can data leak? Encryption, field allowlists, generic errors
Denial of service Can it be overwhelmed? Rate limiting, input size caps, timeouts
Elevation of privilege Can a user gain rights they shouldn't? Authorization checks, least privilege

Read the full file on GitHub · 526 lines

Changes

What this file has done since we first saw it

Hashed on every crawl. A supply-chain change to an agent config is a question of when, not whether, so the history is kept rather than the latest state alone.

  1. today Changed · +23 tokens per session c2129d14d7aa
  2. 3d ago Changed · +11 lines e22bb1eb27ad
  3. 6d ago Changed · +14 lines · +25 tokens per session 9c11cdd59cf6
  4. 10d ago First seen · 501 lines · 65 tokens per session scan B 16722c4b5226

Subscribe to this mod's changes

security-and-hardening is a skill published in the GitHub repository mamahoos/dot-files (4 stars, last pushed today), licensed MIT. It adds 113 tokens to every session and 6,393 once invoked, about $0.0006 per session on Opus 5. A static security scan graded it B with 2 findings (cloud metadata endpoint, makes network calls). It is 100% identical to security-and-hardening, differing in 1 line, and is treated as a copy.

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