Web Application Security Testing

Web Application Security Testing is a skill for Claude Code from Masriyan/Claude-Code-CyberSecurity-Skill. It costs 30 tokens per session (3,831 once invoked), scanned B, original, MIT.

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 — 20 skills shipped together

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.

agentmods
npx agentmods add skills/masriyan/claude-code-cybersecurity-skill/09-web-security
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 20 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 Web Application Security Testing

README.md
[![agentmods](https://agentmods.dev/badge/skills/masriyan/claude-code-cybersecurity-skill/09-web-security.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.svg" alt="Measured on agentmods" height="20"></a>
Per session 30 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 3,831 The whole file, excluding the scripts and references it only reads on demand.
Security scan B 2 findings. Scan, not verified.
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 $0.00030 $0.03831
Opus 5 $0.00015 $0.01916
Sonnet 5 $0.00006 $0.00766
Haiku 4.5 $0.00003 $0.00383

Measured 6d ago against content hash de9b7717cf69, method: parsed. Prices are Anthropic first-party input rates as of 2026-09-06, from the pricing page.

Security

Grade B, and why

Web Application Security Testing 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 · 459 lines

How it starts

The opening of the file, as written. The whole thing — 459 lines — stays where its author put it; the contents beside it link to each section on GitHub.

Web Application Security Testing

Purpose

Enable Claude to assist with comprehensive web application security assessments covering OWASP Top 10, injection testing, API security, authentication analysis, and client-side security. Claude analyzes application behavior, generates test payloads, reviews source code, and produces structured vulnerability reports.

Authorization Required: All testing must be performed on authorized targets only. Confirm scope and written authorization before testing.


Activation Triggers

This skill activates when the user asks about:

  • OWASP Top 10 testing or assessment methodology
  • SQL injection, XSS, SSRF, SSTI, command injection testing
  • API security testing (REST, GraphQL, SOAP)
  • Authentication bypass, session management flaws
  • Web application firewall (WAF) bypasses for authorized testing
  • CORS, CSP, or security header analysis
  • OAuth/OIDC security review
  • JWT analysis or manipulation
  • Burp Suite or OWASP ZAP usage guidance
  • Web vulnerability report writing

Prerequisites

pip install requests beautifulsoup4 urllib3 lxml

Recommended tools:

  • Burp Suite Community/Pro — Web proxy and scanner
  • OWASP ZAP — Open-source web scanner
  • sqlmap — Automated SQL injection (authorized use only)
  • Nikto — Web server scanner
  • ffuf / feroxbuster — Web fuzzer
  • jwt_tool — JWT analysis and manipulation

Core Capabilities

1. OWASP Top 10 Assessment

When the user asks to assess for OWASP Top 10 vulnerabilities:

# Vulnerability Claude's Assessment Approach
A01 Broken Access Control Test IDOR, path traversal, forced browsing, privilege escalation
A02 Cryptographic Failures Audit TLS, check sensitive data exposure, weak algorithms
A03 Injection Test all inputs for SQLi, NoSQLi, OS command, LDAP, SSTI
A04 Insecure Design Review architecture for missing security controls
A05 Security Misconfiguration Check defaults, error disclosure, directory listing, debug mode
A06 Vulnerable Components Audit third-party libraries and framework versions
A07 Auth & ID Failures Test session management, brute force, MFA, credential storage
A08 Software & Data Integrity Check update mechanisms, deserialization, CI/CD security
A09 Logging & Monitoring Failures Verify logging coverage and alerting
A10 SSRF Test URL parameters, webhooks, import functionality

Read the full file on GitHub · 459 lines

Files

What ships with it

4 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 First seen · 459 lines · 30 tokens per session scan B de9b7717cf69

Subscribe to this mod's changes

Web Application Security Testing is a skill published in the GitHub repository Masriyan/Claude-Code-CyberSecurity-Skill (395 stars, last pushed 2d ago), licensed MIT. It adds 30 tokens to every session and 3,831 once invoked, about $0.0002 per session on Opus 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.

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