09-web-security

09-web-security is a skill for Claude Code from Masriyan/Claude-Code-CyberSecurity-Skill. It costs 29 tokens per session (4,044 once invoked), scanned B, original, no licence file.

A set of procedures for testing the security of websites and APIs against common weaknesses listed by OWASP, a nonprofit security organization. It requires authorization before testing.

In plain words
What is it for?
It is for testing injections, authentication, sessions, APIs, browser-side protections, and security headers, then producing structured vulnerability reports.
Why use it?
It helps security testers check application behavior and code systematically instead of relying on ad hoc tests.

Skill for Claude Code

Written for Claude Code: shipped in a Claude Code plugin.

Part of the cybersecurity plugin — 22 skills shipped together

Good fit It is for testing injections, authentication, sessions, APIs, browser-side protections, and security headers, then producing structured vulnerability reports.

Compare 6 skills from other repositories ↓
Install with agentmods
npx agentmods add skills/masriyan/claude-code-cybersecurity-skill/09-web-security
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 Masriyan/Claude-Code-CyberSecurity-Skill --skill 09-web-security
Clone the repo
git clone --depth 1 https://github.com/Masriyan/Claude-Code-CyberSecurity-Skill

Made for: Claude Code.

Or install cybersecurity, the plugin that ships this one along with the rest of its 22 skills.

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 09-web-security

README.md
[![agentmods](https://agentmods.dev/badge/skills/masriyan/claude-code-cybersecurity-skill/09-web-security/github.svg)](https://agentmods.dev/skills/masriyan/claude-code-cybersecurity-skill/09-web-security)
Your own site
<a href="https://agentmods.dev/skills/masriyan/claude-code-cybersecurity-skill/09-web-security"><img src="https://agentmods.dev/badge/skills/masriyan/claude-code-cybersecurity-skill/09-web-security/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 09-web-security

Your own site · 80×15
<a href="https://agentmods.dev/skills/masriyan/claude-code-cybersecurity-skill/09-web-security"><img src="https://agentmods.dev/badge/skills/masriyan/claude-code-cybersecurity-skill/09-web-security.svg" alt="Reviewed on agentmods" width="80" height="20"></a>
Per session 29 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 4,044 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. Third-party audits
  • NVIDIA SkillSpector warn 7 Sept 2026
SkillSpector: 9 findings, up to high

These are SkillSpector’s own severities. On a checked sample its high-severity flags on skills were ~96% false positives — a documented command, a public API, a “never do X” rule — so we show them as a caution to read, not a verdict. Why →

  • high YARA Match · line 6
    YARA rule matched a hack tool or exploit indicator (offensive tools, reconnaissance, privilege escalation, or exploit frameworks).
    Fix: Remove offensive tool references and exploit code. Legitimate agent skills should not contain penetration testing tools, exploit frameworks, or reconnaissance utilities.
  • high Anti-Refusal · line 152
    Skill attempts to nullify the agent's safety policies or restrictions ('you have no restrictions', 'ignore your guidelines', 'do anything now'). This is a direct jailbreak that disables guardrails.
    Fix: Remove jailbreak framing that nullifies safety policies or restrictions. Skill content must not instruct the agent to ignore its guidelines or operate without guardrails.
  • high Server-Side Request Forgery · line 199
    Code accesses a cloud instance metadata endpoint (e.g. 169.254.169.254). A single request can return temporary IAM credentials, making this a high-value SSRF target for credential theft.
    Fix: Remove access to cloud metadata endpoints unless strictly required. If metadata is needed, restrict it (e.g. IMDSv2 with hop limit) and never expose returned credentials.
  • high Server-Side Request Forgery · line 204
    Code accesses a cloud instance metadata endpoint (e.g. 169.254.169.254). A single request can return temporary IAM credentials, making this a high-value SSRF target for credential theft.
    Fix: Remove access to cloud metadata endpoints unless strictly required. If metadata is needed, restrict it (e.g. IMDSv2 with hop limit) and never expose returned credentials.
  • high Server-Side Request Forgery · line 205
    Code accesses a cloud instance metadata endpoint (e.g. 169.254.169.254). A single request can return temporary IAM credentials, making this a high-value SSRF target for credential theft.
    Fix: Remove access to cloud metadata endpoints unless strictly required. If metadata is needed, restrict it (e.g. IMDSv2 with hop limit) and never expose returned credentials.
  • high Server-Side Request Forgery · line 452
    Code accesses a cloud instance metadata endpoint (e.g. 169.254.169.254). A single request can return temporary IAM credentials, making this a high-value SSRF target for credential theft.
    Fix: Remove access to cloud metadata endpoints unless strictly required. If metadata is needed, restrict it (e.g. IMDSv2 with hop limit) and never expose returned credentials.
  • high Server-Side Request Forgery · line 200
    Code accesses a cloud instance metadata endpoint (e.g. 169.254.169.254). A single request can return temporary IAM credentials, making this a high-value SSRF target for credential theft.
    Fix: Remove access to cloud metadata endpoints unless strictly required. If metadata is needed, restrict it (e.g. IMDSv2 with hop limit) and never expose returned credentials.
  • high Server-Side Request Forgery · line 452
    Code accesses a cloud instance metadata endpoint (e.g. 169.254.169.254). A single request can return temporary IAM credentials, making this a high-value SSRF target for credential theft.
    Fix: Remove access to cloud metadata endpoints unless strictly required. If metadata is needed, restrict it (e.g. IMDSv2 with hop limit) and never expose returned credentials.
  • medium Excessive Agency · line 281
    Skill enables autonomous high-impact decisions without human-in-the-loop verification. Critical operations (destructive commands, financial transactions, data deletion) should require explicit user confirmation.
    Fix: Add human-in-the-loop confirmation for destructive, irreversible, or high-impact operations. Never auto-execute commands that modify files, send data, or alter system state.
How audits are shown
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 $0.00029 $0.04044
Opus 5.5 $0.00012 $0.01618
Sonnet 5.5 $0.00006 $0.00809
Haiku 4.5 $0.00003 $0.00404

Measured 6d ago against content hash 2f412b01af05, method: parsed. Prices are Anthropic first-party input rates as of 2026-10-07, from the pricing page.

Security

Grade B, and why

09-web-security 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 6d ago.

The scan reads SKILL.md. This mod also ships 2 executable files (scripts/api_security_tester.py, scripts/owasp_scanner.py), listed below but not scanned — reading those needs a real analyzer, not pattern matching.

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.

http://169.254.169.254/ # AWS metadata

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.

requests.get(url, headers={"Origin": "https://evil.com"})
skills/09-web-security/SKILL.md · 480 lines

The source is not reproduced here

A licence we could not identify

The repository carries a LICENSE file, but it is custom or dual enough that GitHub cannot name it and neither can this catalogue. Unknown terms are not permission, so the body is not copied here. Read the licence at the source and decide for yourself.

Read it on GitHub

Files

What ships with it

3 files beside SKILL.md in the same directory: the scripts, references and assets a skill reads on demand. Not counted in the per-session cost; read them before you install if any of them is executable.

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. 6d ago Changed 2f412b01af05
  2. 11d ago Changed · +21 lines · -1 tokens per session ad4a881e6629
  3. 1mo ago Changed 1be873e2f1f9
  4. 1mo ago First seen · 459 lines · 30 tokens per session scan B de9b7717cf69

Subscribe to this mod's changes

09-web-security is a skill published in the GitHub repository Masriyan/Claude-Code-CyberSecurity-Skill (518 stars, last pushed 7d ago), with no licence file. It adds 29 tokens to every session and 4,044 once invoked, about $0.0001 per session on Opus 5.5. A static security scan graded it B with 2 findings (cloud metadata endpoint, makes network calls). No closer match exists in the catalogue, so it is treated as the original; first seen 2026-08-30.