modernize-harden

modernize-harden is a skill for Claude Code from MinhThang1009/dotclaude. It costs 52 tokens per session (674 once invoked), scanned A, original, MIT.

A security review for older code that looks for vulnerabilities and prepares a patch for serious findings. It covers issues such as injection, weak access controls, exposed secrets, and unsafe input handling.

In plain words
What is it for?
Scanning legacy code, ranking findings by severity, checking dependencies, and writing findings plus proposed fixes into an analysis directory for review.
Why use it?
It helps identify security risks in legacy code without directly changing the original legacy directory.

Skill for Claude Code

Written for Claude Code: argument-hint in frontmatter. Also seen: mentions subagents; positional $N argument.

Part of the code-modernization plugin — 7 skills, 5 agents shipped together

Good fit Scanning legacy code, ranking findings by severity, checking dependencies, and writing findings plus proposed fixes into an analysis directory for review.

Compare 6 skills from other repositories ↓
Install with agentmods
npx agentmods add skills/minhthang1009/dotclaude/modernize-harden
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 MinhThang1009/dotclaude --skill modernize-harden
Clone the repo
git clone --depth 1 https://github.com/MinhThang1009/dotclaude

Made for: Claude Code.

Or install code-modernization, the plugin that ships this one along with the rest of its 7 skills, 5 agents.

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 modernize-harden

README.md
[![agentmods](https://agentmods.dev/badge/skills/minhthang1009/dotclaude/modernize-harden/github.svg)](https://agentmods.dev/skills/minhthang1009/dotclaude/modernize-harden)
Your own site
<a href="https://agentmods.dev/skills/minhthang1009/dotclaude/modernize-harden"><img src="https://agentmods.dev/badge/skills/minhthang1009/dotclaude/modernize-harden/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 modernize-harden

Your own site · 80×15
<a href="https://agentmods.dev/skills/minhthang1009/dotclaude/modernize-harden"><img src="https://agentmods.dev/badge/skills/minhthang1009/dotclaude/modernize-harden.svg" alt="Reviewed on agentmods" width="80" height="20"></a>
Per session 52 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 674 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 $0.00052 $0.00674
Opus 5 $0.00026 $0.00337
Sonnet 5 $0.00010 $0.00135
Haiku 4.5 $0.00005 $0.00067

Measured 10d ago against content hash b56219cb0857, method: parsed. Prices are Anthropic first-party input rates as of 2026-09-10, from the pricing page.

Security

Grade A, and why

modernize-harden 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 10d 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.

plugins/code-modernization/skills/modernize-harden/SKILL.md · 66 lines

How it starts

The opening of the file, as written. The whole thing — 66 lines — stays where its author put it; the contents beside it link to each section on GitHub.

Run a security hardening pass on legacy/$1: find vulnerabilities, rank them, and produce a reviewable patch for the critical ones.

This command never edits legacy/ — it writes findings and a proposed patch to analysis/$1/. The user reviews and applies (or not).

Scan

Spawn the security-auditor subagent:

"Adversarially audit legacy/$1 for security vulnerabilities. Cover what's relevant to the stack: injection (SQL/NoSQL/OS command/template), broken auth, sensitive data exposure, access control gaps, insecure deserialization, hardcoded secrets, vulnerable dependency versions, missing input validation, path traversal. For each finding return: CWE ID, severity (Critical/High/Med/Low), file:line, one-sentence exploit scenario, and recommended fix. Run any available SAST tooling (npm audit, pip-audit, OWASP dependency-check) and include its raw output."

Triage

Write analysis/$1/SECURITY_FINDINGS.md:

  • Summary scorecard (count by severity, top CWE categories)
  • Findings table sorted by severity
  • Dependency CVE table (package, installed version, CVE, fixed version)

Remediate

For each Critical and High finding, draft a minimal, targeted fix. Do not edit legacy/ — write all fixes as a single unified diff to analysis/$1/security_remediation.patch, with a comment line above each hunk citing the finding ID it addresses (# SEC-001: parameterize the query).

Add a Remediation Log section to SECURITY_FINDINGS.md mapping each finding ID → one-line summary of the proposed fix and the patch hunk that implements it.

Verify

Spawn the security-auditor again to review the patch against the original code:

"Review analysis/$1/security_remediation.patch against legacy/$1. For each hunk: does it fully remediate the cited finding? Does it introduce new vulnerabilities or change behavior beyond the fix? Return one verdict per hunk: RESOLVES / PARTIAL / INTRODUCES-RISK, with a one-line reason."

Add a Patch Review section to SECURITY_FINDINGS.md with the verdicts. If any hunk is PARTIAL or INTRODUCES-RISK, revise the patch and re-review.

Read the full file on GitHub · 66 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. 10d ago First seen · 66 lines · 52 tokens per session scan A b56219cb0857

Subscribe to this mod's changes

modernize-harden is a skill published in the GitHub repository MinhThang1009/dotclaude (20 stars, last pushed 1mo ago), licensed MIT. It adds 52 tokens to every session and 674 once invoked, about $0.0003 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 2026-08-30.

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