arnesto: Skill for Claude Code

.agents/skills/xp-security-analysis/SKILL.md

xp-security-analysis is a skill for Claude Code, Codex from saski/arnesto. It costs 37 tokens per session (275 once invoked), scanned A, original, Unlicense.

A security-review guide for examining code, system design, or architecture for realistic weaknesses. It uses common security practices such as OWASP and threat modeling, which means thinking through how an attacker could misuse a system.

In plain words
What is it for?
Use it for security reviews, risk assessments, attack-scenario analysis, and concrete fixes for issues such as injection, broken access control, or unsafe configuration.
Why use it?
It helps find practical vulnerabilities, unsafe assumptions, exposed secrets, and other risks before they cause production damage.

Skill for Claude CodeCodex

Written for no agent in particular: nothing here depends on one. Also seen: installed under .agents/ (shared by several agents).

This is saski/arnesto's own configuration. It tells Claude Code and Codex how to work on arnesto itself, so it is not a mod to install elsewhere. Copy it as a starting point and replace the rules that are about this project. Everything arnesto configures →

Reuse

Borrowing it

Nothing to install: this file belongs to saski/arnesto. Take a copy, put it at the same path in your own repository, and replace the rules that are about this project with yours.

Copy the file
curl -O https://raw.githubusercontent.com/saski/arnesto/main/.agents/skills/xp-security-analysis/SKILL.md
Clone the repo
git clone --depth 1 https://github.com/saski/arnesto

Made for: Claude Code, Codex.

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 xp-security-analysis

README.md
[![agentmods](https://agentmods.dev/badge/skills/saski/arnesto/xp-security-analysis.svg)](https://agentmods.dev/skills/saski/arnesto/xp-security-analysis)
Your own site
<a href="https://agentmods.dev/skills/saski/arnesto/xp-security-analysis"><img src="https://agentmods.dev/badge/skills/saski/arnesto/xp-security-analysis.svg" alt="Measured on agentmods" height="20"></a>
Per session 37 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 275 The whole file, excluding the scripts and references it only reads on demand.
Security scan A 0 findings. A grade says what 26 rules found in the file — not that it is safe.
Origin original No closer match found 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 $0.00037 $0.00275
Opus 5 $0.00018 $0.00138
Sonnet 5 $0.00007 $0.00055
Haiku 4.5 $0.00004 $0.00028

Measured 3d ago against content hash ca7523ce6c96, method: parsed. Prices are Anthropic first-party input rates as of 2026-09-06, from the pricing page.

Security

Grade A, and why

xp-security-analysis scanned grade A with 0 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 3d ago.

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.

Nothing flagged

None of the 26 patterns this scan looks for appear in this file: no shell pipes, no recursive deletes, no credential paths, no hidden text, no instruction-override or anti-refusal phrasing, no agent-config snooping. That is not a guarantee, it is the absence of the things that are checkable.

.agents/skills/xp-security-analysis/SKILL.md · 28 lines

What it actually says

Security Expert — Deep, Pragmatic Risk Analysis

Act as a senior security expert with experience in OWASP, threat modeling, cloud security, secure engineering, and production risk assessment. Your goal is to identify real, practical vulnerabilities and recommend simple, high-value mitigations without adding unnecessary complexity.

Task

Analyze the code, architecture, or system from a security perspective, focusing on:

  • Attack surface and weak entry points
  • Insufficient validation, untrusted inputs, injection vectors
  • Dependency risks, secret/credential exposure, unsafe configuration
  • Common failure modes: insecure deserialization, session issues, broken authorization, etc.
  • Behavior under stress, unexpected conditions, or malformed data

Deliverables

Provide:

  1. Identified risks, clearly described and prioritized
  2. Realistic exploitation scenarios showing how each risk could impact production
  3. Concrete, lightweight mitigations to reduce risk without adding friction
  4. Ongoing defensive practices to keep the system secure over time

Stay pragmatic: minimal complexity, maximum clarity, high reliability.

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. 3d ago First seen · 28 lines · 37 tokens per session scan A ca7523ce6c96

Subscribe to this mod's changes

xp-security-analysis is a skill published in the GitHub repository saski/arnesto (5 stars, last pushed today), licensed Unlicense. It adds 37 tokens to every session and 275 once invoked, about $0.0002 per session on Opus 5. A static security scan graded it A with 0 findings. No closer match exists in the catalogue, so it is treated as the original; first seen 2026-09-03.