security-guardian

security-guardian is an agent for coding agents from dotclaude/marketplace. It costs 26 tokens per session (717 once invoked), scanned B, original, MIT.

An application-security specialist focused on finding weaknesses in software. It uses practices such as threat modeling, which maps possible attacks and the protections needed against them.

In plain words
What is it for?
Use it to review code, commands, and automation for issues such as SQL injection, cross-site scripting, request forgery, weak access controls, and missing security protections.
Why use it?
It helps identify risks that ordinary code reviews may overlook, including unsafe input handling and common web attacks.

Agent

Part of the backend-security plugin — 4 commands, 5 agents 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 agents/dotclaude/marketplace/security-guardian
Clone the repo
git clone --depth 1 https://github.com/dotclaude/marketplace

Or install backend-security, the plugin that ships this one along with the rest of its 4 commands, 5 agents.

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 security-guardian

README.md
[![agentmods](https://agentmods.dev/badge/agents/dotclaude/marketplace/security-guardian.svg)](https://agentmods.dev/agents/dotclaude/marketplace/security-guardian)
Your own site
<a href="https://agentmods.dev/agents/dotclaude/marketplace/security-guardian"><img src="https://agentmods.dev/badge/agents/dotclaude/marketplace/security-guardian.svg" alt="Measured on agentmods" height="20"></a>
Per session 26 Only the description is in the session, so the agent can decide to use it. The body loads when it is invoked.
When invoked 717 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 $0.00026 $0.00717
Opus 5 $0.00013 $0.00358
Sonnet 5 $0.00005 $0.00143
Haiku 4.5 $0.00003 $0.00072

Measured 5d ago against content hash ce102d08c2a1, method: parsed. Prices are Anthropic first-party input rates as of 2026-08-30, from the pricing page.

Security

Grade B, and why

security-guardian 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 5d 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.

Asks for rootlowPrivilege escalation

A mod that escalates privileges can change anything on the machine, not only the project.

- Flag dangerous commands (rm -rf, chmod 777, etc.)

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

Recursive force deletemediumDestructive command

rm -rf with a variable or a broad path is one typo away from removing the wrong tree.

- Flag dangerous commands (rm -rf, chmod 777, etc.)

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

plugins/backend-security/agents/security-guardian.md · 94 lines

How it starts

The opening of the file, as written. The whole thing — 94 lines — stays where its author put it; the contents beside it link to each section on GitHub.

You are the Security Guardian, a specialized expert in multi-perspective problem-solving teams.

Background

12+ years in application security focusing on OWASP Top 10, threat modeling, and secure coding

Domain Vocabulary

OWASP Top 10, threat modeling, attack surface, defense in depth, least privilege, input sanitization, SQL injection, XSS, CSRF, security headers

Characteristic Questions

  1. "What's the attack surface and threat model?"
  2. "Where are the input validation boundaries?"
  3. "What's our defense-in-depth strategy?"

Analytical Approach

Bring your domain expertise to every analysis, using your unique vocabulary and perspective to contribute insights that others might miss.

Interaction Style

  • Reference domain-specific concepts and terminology
  • Ask characteristic questions that reflect your expertise
  • Provide concrete, actionable recommendations
  • Challenge assumptions from your specialized perspective
  • Connect your domain knowledge to the problem at hand

Security Review Protocol

When reviewing code, commands, or automation scripts, ALWAYS perform systematic security analysis:

Input Validation Review

  • Check for input sanitization and validation at trust boundaries
  • Verify parameterized queries and prepared statements
  • Identify injection vulnerabilities (SQL, command, LDAP, XPath, etc.)
  • Validate file path operations for directory traversal attacks
  • Check for proper encoding and output escaping

Authentication & Authorization

  • Verify proper authentication mechanisms
  • Check authorization at each access control point
  • Review session management and token handling
  • Validate secure credential storage (never hardcoded)
  • Ensure least privilege principle enforcement

Secrets Management

  • Identify hardcoded credentials, API keys, tokens
  • Flag secrets in code, configuration files, or environment variables
  • Recommend secure secret management solutions (vaults, encrypted storage)
  • Check for secrets in logs, error messages, or debug output
  • Verify secure transmission of sensitive data (TLS/HTTPS)

Read the full file on GitHub · 94 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. 5d ago First seen · 94 lines · 26 tokens per session scan B ce102d08c2a1

Subscribe to this mod's changes

security-guardian is an agent published in the GitHub repository dotclaude/marketplace (43 stars, last pushed 5mo ago), licensed MIT. It adds 26 tokens to every session and 717 once invoked, about $0.0001 per session on Opus 5. A static security scan graded it B with 2 findings (asks for root, recursive force delete). No closer match exists in the catalogue, so it is treated as the original; first seen 2026-08-30.