02 Vulnerability Scanner

---
name: masriyan-02-vulnerability-scanner
description: Dependency auditing, CVE detection, configuration security review, CVSS scoring, and prioritized vulnerability reporting
version: 3.0.0
author: Masriyan
tags: [cybersecurity, vulnerability, scanning, cve, cvss, audit, assessment, dependency]
---

# Vulnerability Scanning & Assessment

## Purpose

Enable Claude to perform comprehensive vulnerability assessments by directly analyzing dependency files, configuration files, and scan output — then generating prioritized, actionable reports. Claude identifies vulnerabilities, calculates risk, and prescribes remediation with version specifics.

---

## Activation Triggers

This skill activates when the user asks about:
- Scanning dependencies for known CVEs
- Auditing `requirements.txt`, `package.json`, `go.mod`, `pom.xml`, `Cargo.toml`
- Reviewing server configurations for security issues
- CVSS scoring or severity calculation
- Vulnerability assessment or security audit reports
- Checking software versions against known exploits
- Configuration hardening for nginx, Apache, SSH, Docker, Kubernetes
- NVD, OSV, or CVE database queries

---

## Prerequisites

```bash
pip install requests packaging jinja2 pyyaml
```

**Optional enhanced tools:**
- `nuclei` — Template-based vulnerability scanner
- `trivy` — Container and filesystem scanner
- `nmap` with NSE scripts — Network vuln scanning
- `openvas` — Full vulnerability management

---

## Core Capabilities

### 1. Dependency Vulnerability Auditing

Claude can directly read and analyze dependency files:

**When the user asks to audit dependencies:**

1. **Read the dependency file** using Claude's Read tool or ask the user to paste it
2. **Identify package manager** from file format:
   - `requirements.txt` / `Pipfile.lock` / `pyproject.toml` → Python/pip
   - `package.json` / `package-lock.json` / `yarn.lock` → Node.js/npm
   - `go.mod` / `go.sum` → Go modules
   - `pom.xml` / `build.gradle` → Java/Maven/Gradle
   - `Cargo.toml` / `Cargo.lock` → Rust/Cargo
   - `Gemfile.lock` → Ruby/Bundler
   - `composer.lock` → PHP/Composer
3. **Extract exact versions** for all direct and transitive dependencies
4. **Query vulnerability databases** — Claude can search NVD API, OSV, and GitHub Advisory Database for each package+version combination
5. **Calculate CVSS v3.1 severity** for each finding
6. **Check for available patches** — identify the minimum safe version
7. **Generate prioritized remediation report**

**Use this command to run the automated audit:**
```bash
python scripts/dependency_auditor.py --project-dir ./myapp --format json --output audit.json
python scripts/dependency_auditor.py --requirements requirements.txt --severity high,critical
```

**Claude's native analysis** — When running without scripts, analyze pasted dependency content directly:
- Flag packages with `>= `, `*`, or missing version pins (supply chain risk)
- Identify known high-risk packages (log4j, spring-core, struts, etc.)
- Cross-reference with CISA KEV (Known Exploited Vulnerabilities) catalog

### 2. Configuration Security Auditing

Claude can directly read and analyze configuration files:

**When the user asks to audit a configuration:**

#### Nginx Audit Checklist
```
[ ] ssl_protocols — Must NOT include SSLv2, SSLv3, TLSv1, TLSv1.1
[ ] ssl_ciphers — Must not include RC4, DES, MD5, EXPORT ciphers
[ ] server_tokens — Should be 'off' (hides version)
[ ] add_header X-Frame-Options — Required (SAMEORIGIN or DENY)
[ ] add_header X-Content-Type-Options — Required (nosniff)
[ ] add_header Strict-Transport-Security — Required (min 1 year)
[ ] add_header Content-Security-Policy — Required
[ ] autoindex — Must be 'off' (prevents directory listing)
[ ] client_max_body_size — Should be set (prevents DoS)
[ ] access_log / error_log — Must be enabled
```

#### SSH (sshd_config) Audit Checklist
```
[ ] PermitRootLogin — Should be 'no' or 'prohibit-password'
[ ] PasswordAuthentication — Should be 'no' (key-only)
[ ] PermitEmptyPasswords — Must be 'no'
[ ] Protocol — Should be '2' only
[ ] Port — Consider non-default port
[ ] AllowUsers / AllowGroups — Explicit allowlist preferred
[ ] MaxAuthTries — Should be 3-5
[ ] LoginGraceTime — Should be 30-60s
[ ] ClientAliveInterval — Enable session timeout
[ ] X11Forwarding — Should be 'no' if unused
[ ] UsePAM — Review PAM configuration
```

#### Docker/Dockerfile Audit Checklist
```
[ ] USER — Must not run as root; add non-root user
[ ] Image tags — Must not use 'latest'; pin specific digest
[ ] COPY vs ADD — Prefer COPY; ADD has implicit extraction risks
[ ] Secrets — No RUN commands with passwords/tokens
[ ] Multi-stage builds — Minimize attack surface
[ ] HEALTHCHECK — Define health monitoring
[ ] .dockerignore — Exclude .env, keys, secrets
[ ] Read-only filesystem — Use --read-only where possible
```

#### Kubernetes YAML Audit Checklist
```
[ ] securityContext.runAsNonRoot — Must be true
[ ] securityContext.readOnlyRootFilesystem — Should be true
[ ] securityContext.allowPrivilegeEscalation — Must be false
[ ] capabilities — Drop ALL, add only required
[ ] resources.limits — CPU and memory limits required
[ ] NetworkPolicy — Restrict pod-to-pod communication
[ ] ServiceAccount — Disable automount if not needed
[ ] secrets — Use sealed secrets or external vaults
[ ] hostPID/hostIPC/hostNetwork — Must be false
[ ] privileged — Must never be true in production
```

### 3. CVSS v3.1 Scoring

**When the user asks to calculate CVSS or assess severity:**

Claude can calculate CVSS v3.1 scores from the vector string or from a vulnerability description:

**CVSS v3.1 Metrics:**
| Metric | Values | Description |
|--------|--------|-------------|
| Attack Vector (AV) | N/A/L/P | Network/Adjacent/Local/Physical |
| Attack Complexity (AC) | L/H | Low/High |
| Privileges Required (PR) | N/L/H | None/Low/High |
| User Interaction (UI) | N/R | None/Required |
| Scope (S) | U/C | Unchanged/Changed |
| Confidentiality (C) | N/L/H | None/Low/High |
| Integrity (I) | N/L/H | None/Low/High |
| Availability (A) | N/L/H | None/Low/High |

**Severity Ranges:**
| Score | Severity |
|-------|----------|
| 0.0 | None |
| 0.1–3.9 | Low |
| 4.0–6.9 | Medium |
| 7.0–8.9 | High |
| 9.0–10.0 | Critical |

**Example calculation:**
- Remote unauthenticated RCE: `AV:N/AC:L/PR:N/UI:N/S:C/C:H/I:H/A:H` → 10.0 (Critical)
- Local privilege escalation: `AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H` → 7.8 (High)

```bash
python scripts/cvss_calculator.py --vector "AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H"
```

### 4. Network Vulnerability Scanning Integration

**When the user provides Nmap scan results or asks to scan for vulnerabilities:**

1. Parse Nmap XML/grepable output for open services and versions
2. Map each service+version to known CVEs
3. Flag services with default credentials (check CVE/common credential lists)
4. Identify critical misconfigurations (anonymous FTP, open relay, telnet, etc.)
5. Provide targeted Nmap NSE script commands for deeper testing:

```bash
# Vulnerability scanning with NSE
nmap -sV --script vuln -p 80,443,22,21,3389 target.com

# SMB vulnerability check (EternalBlue, etc.)
nmap -p 445 --script smb-vuln* target.com

# SSL/TLS vulnerability check
nmap -p 443 --script ssl-enum-ciphers,ssl-heartbleed,ssl-poodle target.com
```

### 5. Vulnerability Report Generation

**When the user asks for a vulnerability report:**

Generate reports in this structure:

```markdown
# Vulnerability Assessment Report
**Target:** [Target Name/IP Range]
**Date:** [Date]
**Scope:** [Authorized scope]
**Assessor:** [Name]

---

## Executive Summary
[2-3 sentences: what was tested, total findings by severity, top risk]

## Finding Summary
| Severity | Count | Examples |
|----------|-------|---------|
| Critical | 2 | CVE-2021-44228 (Log4Shell), Unauthenticated RCE |
| High | 5 | Outdated TLS, SQLi in /api/users |
| Medium | 12 | Missing security headers, verbose errors |
| Low | 8 | Information disclosure, weak ciphers |
| Info | 15 | Version disclosure, directory listing |

---

## Findings Detail

### CRITICAL-01: [Finding Title]
**CVSS:** 9.8 (Critical) | AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
**Affected:** [Package/Service] [Version]
**CVE:** [CVE-ID]
**Description:** [Clear technical description]
**Evidence:** [Proof the vulnerability exists]
**Remediation:** Upgrade to [Package] >= [SafeVersion]
**References:** [CVE link, advisory]

---

## Remediation Roadmap
| Priority | Action | Effort | Risk Reduction |
|----------|--------|--------|----------------|
| Immediate | Patch Log4j to 2.17.1+ | Low | Critical |
| This week | Upgrade express to 4.18.2 | Low | High |
| This month | Enable WAF rules | Medium | Medium |
```

---

## Output Standards

Always produce findings with:
- **CVE ID** (where applicable)
- **CVSS v3.1 score and vector**
- **Affected version** and **safe version**
- **PoC evidence** (non-destructive confirmation only)
- **Remediation steps** with specific version numbers
- **Compliance mapping** (PCI-DSS, SOC2, CIS) where relevant

---

## Script Reference

### `dependency_auditor.py`
```bash
python scripts/dependency_auditor.py --project-dir ./myapp --format json --output audit.json
python scripts/dependency_auditor.py --requirements requirements.txt --severity high,critical
```

### `config_auditor.py`
```bash
python scripts/config_auditor.py --type nginx --config /etc/nginx/nginx.conf --output audit.json
python scripts/config_auditor.py --type sshd --config /etc/ssh/sshd_config
python scripts/config_auditor.py --type dockerfile --config Dockerfile
```

### `cvss_calculator.py`
```bash
python scripts/cvss_calculator.py --vector "AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H"
python scripts/cvss_calculator.py --interactive
```

---

## Skill Integration

| Condition | Next Skill |
|-----------|------------|
| Vulnerabilities confirmed → develop PoC | → Skill 03 (Exploit Development) |
| Vulnerabilities found → apply fixes | → Skill 15 (Blue Team Defense) |
| Auto-ticket for SOC | → Skill 11 (CSOC Automation) |
| Discovered during recon | ← Skill 01 (Recon & OSINT) |

---

## References

- [NVD — National Vulnerability Database](https://nvd.nist.gov/)
- [OSV — Open Source Vulnerabilities](https://osv.dev/)
- [CISA KEV Catalog](https://www.cisa.gov/known-exploited-vulnerabilities-catalog)
- [CVSS v3.1 Specification](https://www.first.org/cvss/v3.1/specification-document)
- [CIS Benchmarks](https://www.cisecurity.org/cis-benchmarks)
- [OWASP Dependency-Check](https://owasp.org/www-project-dependency-check/)


---

## v3.0 Enhancements (2026 Update)

**Risk-based prioritization beyond raw CVSS:**

- **CVSS 4.0** — score with the current standard (Base/Threat/Environmental/Supplemental); show the vector string and note when only v3.1 data exists.
- **EPSS + CISA KEV** — combine **CVSS severity × EPSS exploit-probability × KEV membership**. A medium-CVSS CVE that is in the CISA Known Exploited Vulnerabilities catalog or has high EPSS outranks a high-CVSS CVE with no exploitation signal. Always state "patch-first" order on this combined basis.
- **SBOM + VEX** — generate a CycloneDX/SPDX SBOM of the project and emit VEX statements (`affected` / `not_affected` / `fixed`) so consumers know which CVEs are actually reachable.
- **Reachability analysis** — flag whether a vulnerable function is actually called (call-graph/import reachability) to cut false-positive noise from transitive deps.
- **OSV.dev** — query the OSV API for ecosystem-precise advisories (PyPI, npm, Go, crates, Maven) in addition to NVD.

**Output rule:** every finding row carries `CVSS | EPSS | KEV(Y/N) | Reachable(Y/N/Unknown) | Fix`.

### Added references
- [CISA KEV Catalog](https://www.cisa.gov/known-exploited-vulnerabilities-catalog)
- [FIRST EPSS](https://www.first.org/epss/) · [OSV.dev](https://osv.dev/) · [CVSS 4.0](https://www.first.org/cvss/v4-0/)