What is blue-team-defender?

A defensive security agent that reviews reported vulnerabilities and applies fixes and hardening measures. It focuses on protecting applications, APIs, authentication, authorisation, and user sessions.

Use it to triage security issues, fix application and API vulnerabilities, add security headers and rate limits, improve login and session security, and document the work.

It turns security findings into code changes and regression tests, helping prevent the same vulnerabilities from returning. It also addresses common weaknesses such as missing access checks, unsafe input handling, and weak rate limits.

blue-team-defender — Agent for Claude Code by lucasrosati

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.

Clone the repo

git clone --depth 1 https://github.com/lucasrosati/claude-security-agents

Made for: Claude Code.

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.

README.md

[![agentmods](https://agentmods.dev/badge/agents/lucasrosati/claude-security-agents/blue-team-defender/github.svg)](https://agentmods.dev/agents/lucasrosati/claude-security-agents/blue-team-defender)

Your own site

<a href="https://agentmods.dev/agents/lucasrosati/claude-security-agents/blue-team-defender"><img src="https://agentmods.dev/badge/agents/lucasrosati/claude-security-agents/blue-team-defender/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.

Your own site · 80×15

<a href="https://agentmods.dev/agents/lucasrosati/claude-security-agents/blue-team-defender"><img src="https://agentmods.dev/badge/agents/lucasrosati/claude-security-agents/blue-team-defender.svg" alt="Reviewed on agentmods" width="80" height="20"></a>

Per session 42 Only the description is in the session, so the agent can decide to use it. The body loads when it is invoked.

When invoked 1,165 The whole file, excluding the scripts and references it only reads on demand.

Security scan A 0 findings. A grade says what 26 rules found in the file — not that it is safe.

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.

Model	Per session	Once invoked
Fable 5.1	$0.00042	$0.01165
Opus 5.5	$0.00017	$0.00466
Sonnet 5.5	$0.00008	$0.00233
Haiku 4.5	$0.00004	$0.00117

Measured 2mo ago against content hash 0c6749eba389, method: parsed. Prices are Anthropic first-party input rates as of 2026-10-07, from the pricing page.

Security

Grade A, and why

blue-team-defender 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 2mo 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.

agents/blue-team-defender.md · 142 lines

How it starts

The opening of the file, as written. The whole thing — 142 lines — stays where its author put it; the contents beside it link to each section on GitHub.

You are the Blue Team Defender for this project.

Identity

Senior Security Engineer specialized in defense, hardening, and compliance
Deep knowledge of GDPR, LGPD, HIPAA, OWASP
Focused on practical fixes that don't break functionality

Workflow

Triage: classify vulnerabilities by severity and impact
Reverse Engineering: understand the attack vector of each vuln
Fix: implement the fix in code
Test: add regression tests for each fix
Hardening: apply general security improvements
Documentation: generate complete report

Areas of Remediation

1. Authentication & Authorization

Implement rate limiting on login/signup/reset
Fix JWT (validation, expiration, refresh rotation)
Fix IDOR (verify ownership on each request)
Ensure role validation on all protected routes
Password hashing with bcrypt/argon2 (adequate cost)
Session invalidation on logout/password change

2. API Security

Add authentication to exposed endpoints
Implement object-level authorization
Block mass assignment (whitelist accepted fields)
Add input validation with zod/joi on all endpoints
Rate limiting per endpoint and per user
Remove enumeration (generic responses on auth)

3. Input Validation & Injection

Parameterized queries (never string concatenation)
Input sanitization with DOMPurify or similar
Path traversal validation
SSRF protection (URL/IP whitelist)
Strict Content-Type validation
Output encoding against XSS

4. File Uploads

Type validation via magic bytes (don't trust extensions)
File size limits
Rename files on upload (never use original name)
Private storage by default
Malware scanning if applicable
Serve files via signed URLs with expiration

5. Data Security & Compliance

Remove hardcoded secrets → move to env vars
Encrypt sensitive data at rest
Audit logging for access to sensitive data
Sanitize logs (never log PII, tokens, passwords)
Secure token storage (httpOnly, secure, sameSite)
Implement data retention policy
Consent management for sensitive data

Read the full file on GitHub · 142 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.

2mo ago First seen · 142 lines · 42 tokens per session scan A 0c6749eba389

Subscribe to this mod's changes

blue-team-defender is an agent published in the GitHub repository lucasrosati/claude-security-agents (24 stars, last pushed 6mo ago), licensed MIT. It adds 42 tokens to every session and 1,165 once invoked, about $0.0002 per session on Opus 5.5. 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 2026-08-30.

Claude Code Security agents ai-agents blue-team cybersecurity devtools

blue-team-defender next to 6 agents from other repositories
Mod	Type	Stars	Last push	Licence	Scan	Tokens	Works with
blue-team-defenderlucasrosati/claude-security-agents	Agent	24	6mo ago	MIT	A	42	Claude Code
detection-engineerroodlicht/accans-sec-skills	Agent	4	5mo ago	none	A	63	Claude Code
threat-modelerroodlicht/accans-sec-skills	Agent	4	5mo ago	none	A	43	Claude Code
autopilotguib1/red-team-docker	Agent	1	7mo ago	none	A	84	Claude Code
web3-auditorguib1/red-team-docker	Agent	1	7mo ago	none	A	101	Claude Code
validatorguib1/red-team-docker	Agent	1	7mo ago	none	A	64	Claude Code
recon-rankerguib1/red-team-docker	Agent	1	7mo ago	none	A	57	Claude Code