Open-source plugin · Claude Code

A senior cybersecurity specialist that lives inside Claude Code

Claude Cyber turns Claude into a full-spectrum InfoSec professional — offensive, application security, defensive and governance. Not a prompt pack: an ethical, grounded expert that refuses unauthorized work, cites real data instead of guessing, and can teach any concept from the basics.

$claude plugin marketplace add unicorn-rm/Claude-cyber
$claude plugin install security@claude-cyber
29
Skills
6
Agents
7
Commands
4
Domains
21
References
scope requiredATT&CK T1190Claude Cyber — pentester mascot
01

Why it’s different

Every skill is built on the same spine — it won’t act without authorization, won’t invent a fact, and won’t leave you behind.

Guardrail

Authorization-gated

Before any active offensive step it demands a defined engagement scope. Out-of-scope or unauthorized targets are refused — and it never records authorization you don’t hold.

Grounding

Grounded, never guesses

Every CVE, CVSS, EPSS, CISA KEV, MITRE ATT&CK, CWE and OWASP reference is pulled from authoritative sources, with live-lookup recipes for NVD, EPSS and KEV. It won’t invent a CVE or a score.

Companion

Teaches from zero

Senior depth, but it explains any concept from first principles with plain analogies. Ask it to go deeper or start over — a tool and a companion that meets you at your level.

02

Five layers, one contract

Authorization and grounding wrap everything; methodology, agents and commands sit on top. Every skill follows the same seven-beat contract.

1Authorization gateScope & Rules of Engagement enforced before any active work.
2Grounding layerAuthoritative source registry, “never fabricate” rules, canonical finding schema.
3Methodology skillsSenior know-how per domain — the 29 skills.
4Expert agentsSenior personas that orchestrate the skills.
5Workflow commandsDeliberate entry points for repeatable processes.
The skill contract

What every skill guarantees, in order

senior methodology→explain from basics→grounding · CWE/ATT&CK/OWASP→non-destructive confirmation→tooling & how to read output→remediation / defender view→record on the finding schema
03

Six operators, one Flipper

The mascot appears in role variants — each colour is a security discipline, and each maps 1:1 to an agent you can call by name.

Pentester

Pentester

agent: pentester

Runs authorized offensive engagements end to end. Maps the external and internal attack surface, finds and safely confirms in-scope vulnerabilities, chains them into real impact, and writes each one up on the canonical finding schema — always inside the agreed scope.

Skillsrecon-osintnetwork-pentestweb-exploitationactive-directorycloud-pentestprivilege-escalationpost-exploitation
Commands/recon/triage/cvss
Blue-team defender

Blue-team defender

agent: blue-team-analyst

Defends and investigates. Writes and tunes detections, runs the incident-response lifecycle, does disk and memory forensics, hunts for threats that slipped past tooling, analyzes malware safely, and hardens systems to a baseline — turning findings into durable detections.

Skillsdetection-engineeringincident-responsedfir-forensicsthreat-huntingmalware-analysishardening-baselines
Commands/ir
AppSec reviewer

AppSec reviewer

agent: appsec-reviewer

Secures the code before it ships. Reviews source and pull requests by tracing untrusted input to dangerous sinks, triages SAST/DAST output down to confirmed issues, audits dependencies and crypto usage, and proposes concrete secure fixes.

Skillssecure-code-reviewsast-dast-triagedependency-supply-chainsecure-sdlccryptography
Threat modeler

Threat modeler

agent: threat-modeler

Designs security in, before code exists. Builds data-flow diagrams with trust boundaries, enumerates threats with STRIDE and attack trees, rates them, and hands back a prioritized list of mitigations mapped to requirements and tests.

Skillsthreat-modelingsecure-sdlcrisk-assessment-cvss
Commands/threat-model
Vuln triager

Vuln triager

agent: vuln-triager

Turns a noisy pile of findings into a queue you can act on. Deduplicates and confirms, scores technical severity with CVSS, weights real-world risk with EPSS and CISA KEV plus business context, and assigns a risk-based SLA to each.

Skillsrisk-assessment-cvssvulnerability-managementintel-sources
Commands/triage/cvss
Report writer

Report writer

agent: report-writer

Produces the deliverable a client actually reads. An executive summary in business language, technical findings on the canonical schema with evidence and remediation, a prioritized roadmap, retest results, and mapping to compliance controls.

Skillsreport-writingcompliance-mapping
Commands/report
04

29 skills across four domains

Two backbone skills underlie everything; the rest cover the full lifecycle — offense, application security, defense and governance.

Backboneauthorization-gate — scope & refusalintel-sources — grounding, live lookups, finding schema
Offensive11 skills
  • recon-osint
  • network-pentest
  • web-exploitation
  • api-security
  • active-directory
  • cloud-pentest
  • wireless-attacks
  • mobile-pentest
  • privilege-escalation
  • post-exploitation
  • exploit-dev
AppSec5 skills
  • secure-code-review
  • sast-dast-triage
  • dependency-supply-chain
  • secure-sdlc
  • cryptography
Defensive6 skills
  • detection-engineering
  • incident-response
  • dfir-forensics
  • threat-hunting
  • malware-analysis
  • hardening-baselines
GRC5 skills
  • threat-modeling
  • risk-assessment-cvss
  • compliance-mapping
  • vulnerability-management
  • report-writing
web-exploitation — 15 vulnerability classes
SQLiXSSSSRFIDOR / BOLARCEXXESSTIInsecure deserializationFile uploadRequest smugglingOpen redirectHTTP parameter pollutionRace conditionsGraphQL abuseWAF bypass
05

Skills auto-load. Commands are deliberate.

Skills Automatic

Claude auto-loads the right skill when your request matches — “explain SQL injection” pulls web-exploitation; any CVE mention pulls intel-sources.

Commands Explicit

You type /security:… for deliberate workflows and side-effect actions — /security:engagement writes the scope record.

Agents Either

Claude delegates to a persona automatically, or you name it — “use the pentester agent.”

Typical engagement
/engagement→/recon→domain skills · web / network / AD / cloud→/triage/cvss→/report
Defensive branch
detection-engineering→/ir→dfir-forensics→threat-hunting
06

How it was built

A disciplined spec → plan → build, gated by tests that must stay green on every change.

Method

Spec → plan → build

A brainstorm became a written spec, then a phased implementation plan, then the build — with review checkpoints at every phase.

Quality gate

Structural validator

A dependency-free validate_plugin.py keeps every skill consistent — manifest, frontmatter, required references, mandatory gate + grounding markers, hooks and evals. Green on every change.

Behavior tests

A plugin eval suite

Five cases regression-test the flagship behavior: gate refusal, no-fabrication grounding, teaching-from-basics, KEV-aware triage, full CVSS vectors.

Audit trail

PreToolUse hook

A hook logs executed shell commands to .security/audit.log (UTC + command) for the engagement report.

Attribution

Built on open source

Offensive methodology is adapted from the open-source Claude-Red project (MIT, © 2024–2025 SnailSploit / Kai Aizen), rewritten to Claude Cyber’s gate + grounding + finding schema. See NOTICE.md.

Tech & validation

Markdown, YAML, a little Python

Skills, agents and commands are Markdown + YAML; manifests JSON; the validator Python; the hook shell. Shipped after a full end-to-end engagement test — recon → triage → report.

07

Install in two commands

$claude plugin marketplace add unicorn-rm/Claude-cyber
$claude plugin install security@claude-cyber
#then start a new Claude Code session — plugins load at start
Authorized use only

For pentests with a signed scope, bug bounty within program rules, systems you own, labs, CTFs and research. The authorization-gate refuses unauthorized or out-of-scope targets and never fabricates authorization. Not legal advice.