application-security
OWASP Top 10 with code examples, SAST/DAST tools, dependency scanning, CSP headers, and input validation patterns. Use when hardening applications, reviewing security posture, or implementing defensive coding practices.
- Installs
- 175
- Last 24h
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Install
Works with every agent the skills CLI supports.
npx skills add https://github.com/travisjneuman/.claude --skill application-security- 01
Install
Run the command in your project. The CLI asks which agents to install for.
- 02
Describe the task
Ask your agent for something this skill covers. It loads application-security automatically when relevant.
- 03
Review the result
The agent follows the SKILL.md steps, scripts and references bundled with the skill.
SKILL.md
The instructions your agent reads when the skill is triggered.
Application Security Skill
Secure coding patterns, vulnerability prevention, and security tooling for web applications.
OWASP Top 10 (2021) with Code Examples
A01: Broken Access Control
// BAD - No authorization check
app.get('/api/users/:id', async (req, res) => {
const user = await db.user.findUnique({ where: { id: req.params.id } });
res.json(user);
});
// GOOD - Verify ownership or role
app.get('/api/users/:id', authenticate, async (req, res) => {
if (req.user.id !== req.params.id && req.user.role !== 'ADMIN') {
return res.status(403).json({ error: 'Forbidden' });
}
const user = await db.user.findUnique({ where: { id: req.params.id } });
res.json(user);
});
A02: Cryptographic Failures
// BAD - Weak hashing
import crypto from 'crypto';
const hash = crypto.createHash('md5').update(password).digest('hex');
// GOOD - Use bcrypt with proper rounds
import bcrypt from 'bcrypt';
const hash = await bcrypt.hash(password, 12);
const isValid = await bcrypt.compare(password, hash);
A03: Injection
// BAD - SQL injection
const query = `SELECT * FROM users WHERE email = '${email}'`;
// GOOD - Parameterized queries (Prisma handles this automatically)
const user = await prisma.user.findUnique({ where: { email } });
// GOOD - Parameterized raw SQL when needed
const users = await prisma.$queryRaw`SELECT * FROM users WHERE email = ${email}`;
A07: Cross-Site Scripting (XSS)
// BAD - Rendering raw HTML
element.innerHTML = userInput;
// GOOD - Use textContent or framework escaping
element.textContent = userInput;
// GOOD - React auto-escapes by default
return <div>{userInput}</div>;
// BAD in React - dangerouslySetInnerHTML
return <div dangerouslySetInnerHTML={{ __html: userInput }} />;
Content Security Policy (CSP)
Recommended Headers
// Next.js middleware
import { NextResponse } from 'next/server';
export function middleware(request: Request) {
const nonce = crypto.randomUUID();
const csp = [
`default-src 'self'`,
`script-src 'self' 'nonce-${nonce}'`,
`style-src 'self' 'unsafe-inline'`,
`img-src 'self' data: https:`,
`font-src 'self'`,
`connect-src 'self' https://api.example.com`,
`frame-ancestors 'none'`,
`base-uri 'self'`,
`form-action 'self'`,
].join('; ');
const response = NextResponse.next();
response.headers.set('Content-Security-Policy', csp);
response.headers.set('X-Content-Type-Options', 'nosniff');
response.headers.set('X-Frame-Options', 'DENY');
response.headers.set('Referrer-Policy', 'strict-origin-when-cross-origin');
response.headers.set('Permissions-Policy', 'camera=(), microphone=(), geolocation=()');
return response;
}
SAST/DAST Tooling
Static Analysis (SAST)
| Tool | Language | Usage |
|---|---|---|
| ESLint security plugins | JS/TS | eslint-plugin-security, @microsoft/eslint-plugin-sdl |
| Semgrep | Multi | semgrep --config=auto . |
| Bandit | Python | bandit -r src/ |
| gosec | Go | gosec ./... |
| cargo-audit | Rust | cargo audit |
Dynamic Analysis (DAST)
| Tool | Purpose | Usage |
|---|---|---|
| OWASP ZAP | Web app scanning | Proxy-based scanner, API scan mode |
| Nuclei | Vulnerability scanning | Template-based scanner |
| Burp Suite | Manual + automated | Professional penetration testing |
Dependency Scanning
# Node.js
npm audit
npm audit fix
# Python
pip-audit
safety check
# Go
govulncheck ./...
# Rust
cargo audit
Input Validation Patterns
Server-Side Validation (Always Required)
import { z } from 'zod';
const CreateUserSchema = z.object({
email: z.string().email().max(255),
name: z.string().min(1).max(100).regex(/^[a-zA-Z\s'-]+$/),
age: z.number().int().min(0).max(150).optional(),
});
function createUser(input: unknown) {
const validated = CreateUserSchema.parse(input);
// validated is now typed and safe
}
Rate Limiting
import rateLimit from 'express-rate-limit';
const authLimiter = rateLimit({
windowMs: 15 * 60 * 1000, // 15 minutes
max: 5, // 5 attempts per window
message: 'Too many login attempts, please try again later',
standardHeaders: true,
legacyHeaders: false,
});
app.use('/api/auth/login', authLimiter);
Security Checklist
- All user input validated server-side
- Parameterized queries for all database operations
- CSP headers configured
- Rate limiting on auth endpoints
- CORS properly restricted
- Secrets in environment variables, not code
- Dependencies scanned for vulnerabilities
- Authentication tokens in httpOnly cookies
- HTTPS enforced in production
- Error messages don't leak internal details
Related Resources
~/.claude/docs/reference/checklists/security-hardening.md- Security hardening checklist~/.claude/agents/security-auditor.md- Security audit agent~/.claude/skills/authentication-patterns/SKILL.md- Auth patterns
Secure by default. Validate at boundaries. Defense in depth.
FAQ
What does the application-security skill do?
OWASP Top 10 with code examples, SAST/DAST tools, dependency scanning, CSP headers, and input validation patterns. Use when hardening applications, reviewing security posture, or implementing defensive coding practices.
How do I install application-security?
Run npx skills add https://github.com/travisjneuman/.claude --skill application-security in your project. The skills CLI detects the agents you use and copies the skill into the right folder. For Claude Code you can also place the skill folder at ~/.claude/skills/application-security/ (personal) or .claude/skills/application-security/ (project).
Which AI agents can use application-security?
Any agent that supports the open Agent Skills format (a folder with a SKILL.md file), including Claude Code, Codex, Cursor, GitHub Copilot, Gemini CLI, Windsurf, Cline, OpenCode and more.
Is application-security safe to install?
No partner security audit is available yet. Skills can run commands and scripts, so read the SKILL.md and any bundled files before installing.
Who maintains application-security?
It is published by travisjneuman in travisjneuman/.claude. It has 175 recorded installs.
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