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.
npx agentmods add rules/kok-o/koko-contextos-agents/securitygit clone --depth 1 https://github.com/kok-o/koko-contextos-agentsWhat 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.
| Model | Per session | Once invoked |
|---|---|---|
| Fable 5 | $0.00005 | $0.01490 |
| Opus 5 | $0.00003 | $0.00745 |
| Sonnet 5 | $0.00001 | $0.00298 |
| Haiku 4.5 | $0.00001 | $0.00149 |
Grade A, and why
security 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 2d 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.
How it starts
The opening of the file, as written. The whole thing — 216 lines — stays where its author put it; the contents beside it link to each section on GitHub.
Skill: Application Security
Application Security
Overview
Enforces zero-trust defense-in-depth, OWASP Top 10 mitigation, cryptographic hardening, and sensitive data leakage protection across all services and routes.
When to Use
Activate whenever writing authentication, authorization, session management, database queries, cryptography, external API integration, or user input handling.
Negative Constraints (What NOT to Do)
- NEVER use standard string comparison (
===) for secrets/hashes: Always usecrypto.timingSafeEqualto prevent timing attacks. - NEVER store sensitive JWT access/refresh tokens in
localStorage: Store tokens inhttpOnly,Secure,SameSite=Strictcookies. - NEVER return raw database/internal error messages or stack traces to the client: Return standardized generic error codes (
INTERNAL_SERVER_ERROR) and log details internally. - NEVER trust client-provided IDs for authorization without tenant/ownership checks: Always verify
where: { id, userId: session.userId }to prevent Insecure Direct Object References (IDOR). - NEVER disable CSRF protection, CORS allow-all (
*), or TLS verification (NODE_TLS_REJECT_UNAUTHORIZED=0) in production: Always enforce strict origin whitelists and HTTPS.
Rules & Patterns
OWASP Top 10
1. Injection (SQL, NoSQL, Command)
- Always use parameterized queries — never concatenate user input into SQL
- Use ORM (Prisma, SQLAlchemy, TypeORM) — they parameterize by default
- Validate and sanitize all user input
2. Broken Authentication
- Use bcrypt/argon2 for password hashing (cost factor ≥ 12)
- JWT: short-lived access tokens (15min), refresh tokens (7 days)
- Rate limit login attempts
- Implement account lockout after N failed attempts
- MFA for sensitive operations
3. Sensitive Data Exposure
- HTTPS everywhere — redirect HTTP to HTTPS
- Encrypt sensitive data at rest (AES-256)
- Never log passwords, tokens, or PII
- Use environment variables for secrets
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.
- 2d ago First seen · 216 lines · 5 tokens per session scan A e5a531e4f853
security is a cursor rule published in the GitHub repository kok-o/koko-contextos-agents (2 stars, last pushed 2d ago), licensed MIT. It adds 5 tokens to every session and 1,490 once invoked, about $0.0000 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 2026-08-31.
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