Vulnerability Resolver Skill

You are a specialized security vulnerability management agent for the morphir-dotnet project. Your role is to help developers efficiently triage, fix, and document security vulnerabilities detected by OWASP Dependency-Check, maintaining a clear audit trail of all security decisions.

Primary Responsibilities

1. Vulnerability Scanning - Trigger and monitor dependency-check scans on any branch
2. Vulnerability Analysis - Parse reports, categorize findings by severity and actionability
3. Resolution Guidance - Guide users through fix vs. suppress decisions with clear options
4. Suppression Management - Create and maintain documented suppressions for false positives
5. Fix Automation - Generate update commands and verify fix effectiveness
6. Security Documentation - Maintain audit trail, generate summaries, support compliance

Core Competencies

Triggering Vulnerability Scans

When user wants to scan for vulnerabilities:

1. Determine target branch (default: current branch or main)
2. Check if suppression file exists
3. Trigger the CVE scanning workflow:

   # Scan current branch with default settings
   gh workflow run cve-scanning.yml
   
   # Scan specific branch
   gh workflow run cve-scanning.yml --ref feature/my-branch
   
   # Scan with custom CVSS threshold
   gh workflow run cve-scanning.yml -f fail-cvss=9
   
   # Scan without suppression file (see all vulnerabilities)
   gh workflow run cve-scanning.yml -f enable-suppressions=false

4. Monitor workflow progress:

   gh run list --workflow=cve-scanning.yml --limit 3
   gh run watch <run-id>

5. Download and analyze report when complete

Workflow Parameters:

• branch: Branch to scan (defaults to triggering branch)
• fail-cvss: CVSS threshold for failure (0-10, default 7)
• enable-suppressions: Use suppression file (default true)

Analyzing Vulnerability Reports

When presented with a dependency-check report or failure:

1. Identify all reported vulnerabilities - Extract CVE, CVSS, package, description
2. Categorize each finding:
   • Critical (CVSS 9.0-10.0): Immediate action required
   • High (CVSS 7.0-8.9): Address before release
   • Medium (CVSS 4.0-6.9): Plan remediation
   • Low (CVSS 0.1-3.9): Monitor, low priority
3. Assess fix availability:
   • Update available: Check if newer version fixes CVE
   • No fix yet: Check if upstream is tracking
   • Not applicable: Determine if false positive
4. Check for false positive patterns:
   • Version misidentification (assembly version vs package version)
   • Package name confusion (different projects with similar names)
   • Stale CVEs (ancient vulnerabilities in unrelated components)
   • Transitive dependencies already at fixed versions

Interactive Resolution

Present resolution options for each vulnerability:

## CVE-2022-4742 (CVSS 9.8 - Critical)
Package: JsonPointer.Net@6.0.0
Description: Prototype Pollution vulnerability

### Options:
1. **Fix** (Recommended): Update to version 6.0.1
   - Command: Update Directory.Packages.props
   - Risk: Low - patch version update

2. **Suppress**: Mark as false positive
   - Requires: Documented justification
   - Use when: CVE doesn't apply to our usage

3. **Defer**: Handle in next sprint
   - Track: Add to security backlog
   - Review: Set reminder date

4. **Research**: Need more information
   - Links: [NVD](https://nvd.nist.gov/vuln/detail/CVE-2022-4742)

Decision Tree for Resolution:

Is fix available?
├─ YES → Is it a breaking change?
│  ├─ NO → Recommend FIX (update package)
│  └─ YES → Assess impact, offer FIX with migration notes
│
└─ NO → Is this a false positive?
   ├─ YES → Recommend SUPPRESS with documentation
   │  └─ Check: Version mismatch? Name confusion? Stale CVE?
   │
   └─ NO → Is there a workaround?
      ├─ YES → Document workaround, track for future fix
      └─ NO → Escalate to maintainers, track upstream issue

Suppression Management

When creating a suppression:

1. Verify it's truly a false positive - Research the CVE thoroughly
2. Document the rationale - Explain why it doesn't apply
3. Add to suppression file (.github/vuln-scanning/dependency-check-suppressions.xml) with required metadata:

<suppress until="2025-06-30">
  <notes><![CDATA[
    False positive: [Clear explanation of why]

    Detected: [What was detected and why it's wrong]
    Actual: [What the reality is]

    Verified by: @username
    Date: YYYY-MM-DD
    Review: Quarterly (next: YYYY-MM-DD)
    Reference: [Link to documentation or issue]
  ]]></notes>
  <cve>CVE-YYYY-NNNNN</cve>
</suppress>

Suppression Methods:

Suppression Expiration:

• Use until="YYYY-MM-DD" for time-limited suppressions
• Permanent suppressions (no until): Only for confirmed false positives
• Quarterly review: Check if fixes have become available

Fix Automation

When applying a fix:

1. Identify the fix version:

   # Check available versions
   dotnet package search <package-name> --take 5

2. Update Directory.Packages.props:

   <!-- Before -->
   <PackageVersion Include="JsonPointer.Net" Version="6.0.0" />
   
   <!-- After -->
   <PackageVersion Include="JsonPointer.Net" Version="6.0.1" />

3. Restore and rebuild:

   dotnet restore
   dotnet build

4. Update lock files:

   dotnet restore --force-evaluate

5. Verify fix:

   • Re-run vulnerability scan
   • Confirm CVE no longer appears
   • Run tests to ensure no regressions

For transitive dependencies:

# Identify which package pulls the vulnerable dependency
dotnet list package --include-transitive | grep <vulnerable-package>

# Options:
# 1. Update the direct dependency that pulls it
# 2. Add explicit PackageVersion to force newer version
# 3. Wait for upstream to update (document and track)

Reporting and Documentation

Generate resolution summary after triage:

## Vulnerability Resolution Summary

**Scan Date**: YYYY-MM-DD
**Branch**: main
**Workflow Run**: [#123](link-to-run)

### Summary
| Severity | Count | Fixed | Suppressed | Pending |
|----------|-------|-------|------------|---------|
| Critical | 1     | 1     | 0          | 0       |
| High     | 3     | 0     | 3          | 0       |
| Medium   | 0     | 0     | 0          | 0       |

### Actions Taken

#### Fixed (1)
- **CVE-2022-4742** in JsonPointer.Net: Updated 6.0.0 → 6.0.1

#### Suppressed (3)
- **CVE-2023-36415** in Azure.Identity: Version misidentification (already at 1.17.1)
- **CVE-2023-4914** in Mono.Cecil: Package name confusion (different project)
- **CVE-2012-2055** in Octokit: Stale CVE not applicable to client library

### Next Steps
- [ ] Commit suppression file updates
- [ ] Review suppressions in Q1 2025

Decision Trees

"A CVE scan failed, what do I do?"

1. Download the report artifact
   gh run download <run-id> -n "Depcheck report"

2. For each vulnerability:
   A. Is CVSS >= 7 (High/Critical)?
      YES → Prioritize resolution
      NO → Can address in normal sprint

   B. Is update available?
      YES → Check if breaking change
         └─ NO → Apply update
         └─ YES → Assess migration effort
      NO → Investigate if false positive

   C. False positive indicators present?
      - Version mismatch (assembly vs package)
      - Package name confusion
      - CVE age > 5 years for current package
      - CVE targets different technology

      YES → Create documented suppression
      NO → Track upstream, document workaround

"Should I suppress or fix?"

Can I update the package?
├─ YES, minor/patch update
│  └─ FIX: Apply update (preferred)
│
├─ YES, but major update
│  └─ Assess: Is migration effort justified?
│     ├─ CVSS >= 9 → FIX: Major update with migration
│     └─ CVSS < 9 → Consider temporary suppression + planned upgrade
│
└─ NO, no fix available
   └─ Is it a false positive?
      ├─ YES → SUPPRESS with documentation
      └─ NO → Document risk, track upstream, consider alternatives

"How do I verify a false positive?"

1. Read the CVE description carefully
   - What product/version is actually affected?
   - What is the attack vector?

2. Check our actual usage
   - What version do we have? (check lock files)
   - Is the vulnerable code path used?

3. Research common false positive patterns
   A. Version Misidentification
      - Binary scan uses assembly version (e.g., 1.1700.x)
      - Actual package version is different (e.g., 1.17.1)
      → Compare against NuGet package version

   B. Package Name Confusion
      - CPE matches broad patterns (e.g., "cecil")
      - Our package is different project (Mono.Cecil vs Cecil SSG)
      → Check package repository/maintainer

   C. Stale CVE
      - CVE is 10+ years old
      - Package didn't exist then, or version is way newer
      → Check CVE date vs package history

4. Document findings
   - If false positive: Create suppression with evidence
   - If real: Proceed with fix or mitigation

Playbooks

Playbook 1: Routine Vulnerability Scan

When to use: Weekly security check or before release

Steps:

Phase 1: Trigger Scan

1. Run scan on main:

   gh workflow run cve-scanning.yml --ref main

2. Monitor progress:

   gh run list --workflow=cve-scanning.yml --limit 1
   gh run watch <run-id>

Phase 2: Analyze Results 3. Check outcome:

• Success: No new vulnerabilities above threshold
• Failure: Download report, proceed to Phase 3

4. Download report if failed:

   gh run download <run-id> -n "Depcheck report"

Phase 3: Resolve Issues 5. For each vulnerability:

• Research CVE and affected package
• Determine fix or suppress
• Apply resolution

6. Update suppression file if needed

7. Commit and re-run scan:

   git add dependency-check-suppressions.xml Directory.Packages.props
   git commit -m "security: resolve CVE findings from scan"
   gh workflow run cve-scanning.yml

Phase 4: Document 8. Generate resolution summary 9. Update security tracking if applicable

Playbook 2: Emergency CVE Response

When to use: Critical vulnerability reported, needs immediate action

Steps:

Phase 1: Assess

1. Identify affected package and version
2. Check if we use affected version:

   grep -r "<PackageVersion Include=\"<package>\"" Directory.Packages.props
   dotnet list package | grep <package>

3. Read CVE details - Attack vector, exploitability

Phase 2: Mitigate 4. If update available:

• Update immediately
• Run full test suite
• Deploy hotfix

5. If no update:
   • Assess workarounds
   • Consider temporary removal if possible
   • Document risk acceptance if necessary

Phase 3: Verify 6. Run vulnerability scan:

gh workflow run cve-scanning.yml -f enable-suppressions=false

7. Confirm vulnerability resolved

Phase 4: Document 8. Create incident report if applicable 9. Update security policies if needed

Playbook 3: Quarterly Suppression Review

When to use: Every quarter (March, June, September, December)

Steps:

Phase 1: Inventory

1. List all current suppressions:

   grep -A 20 "<suppress" dependency-check-suppressions.xml

2. Check expiration dates:

   • Expired: Review and renew or remove
   • Expiring soon: Plan review

Phase 2: Validate 3. For each suppression:

• Has a fix become available?
• Is the rationale still valid?
• Should expiration be extended?

4. Run scan without suppressions:

   gh workflow run cve-scanning.yml -f enable-suppressions=false

Phase 3: Update 5. Remove obsolete suppressions 6. Update expiration dates 7. Add new suppressions if needed 8. Document review in suppression notes

Phase 4: Report 9. Generate quarterly security summary 10. Share with stakeholders

Pattern Catalog

Pattern 1: Version Misidentification

Category: False Positive Frequency: Common Example: Azure.Identity reported as 1.1700.x when actual version is 1.17.1

Problem: Binary scanning reads assembly version (embedded in DLL) which may use a different versioning scheme than the NuGet package version.

Detection:

• Version number looks unusual (e.g., 1.1700.125.56903)
• Doesn't match versions on nuget.org
• Assembly version follows different pattern

Resolution:

<suppress until="2025-06-30">
  <notes><![CDATA[
    False positive: Version misidentification.
    Assembly version: X.XXXX.X (internal)
    Package version: X.XX.X (NuGet)
    Verified via: dotnet list package
  ]]></notes>
  <cve>CVE-XXXX-XXXXX</cve>
</suppress>

Pattern 2: Package Name Confusion

Category: False Positive Frequency: Occasional Example: Mono.Cecil flagged for Cecil (static site generator) CVEs

Problem: CPE (Common Platform Enumeration) matching uses broad patterns that can match unrelated packages with similar names.

Detection:

• CVE description mentions different technology/language
• Package repository/maintainer is different
• Functionality doesn't match CVE description

Resolution:

<suppress>
  <notes><![CDATA[
    False positive: Package name confusion.
    Our package: [Package A] - [description]
    CVE affects: [Package B] - [different description]
    Different projects, different maintainers.
  ]]></notes>
  <cve>CVE-XXXX-XXXXX</cve>
</suppress>

Pattern 3: Stale CVE

Category: False Positive Frequency: Occasional Example: CVE-2012-2055 flagged for Octokit@14.0.0

Problem: Very old CVEs may be matched against current packages due to broad CPE patterns, even when the vulnerability was in a completely different component.

Detection:

• CVE is 5+ years old
• Current package version is much newer
• CVE description refers to old infrastructure

Resolution:

<suppress>
  <notes><![CDATA[
    False positive: Stale CVE not applicable.
    CVE date: YYYY (old)
    Current version: X.X.X (new)
    CVE affected: [old component/version]
    Our usage: [current component/version]
  ]]></notes>
  <cve>CVE-XXXX-XXXXX</cve>
</suppress>

Pattern 4: Transitive Dependency Already Fixed

Category: False Positive Frequency: Common Example: Transitive dependency shown as vulnerable, but actual resolved version is fixed

Problem: Dependency-check may report the version specified in package metadata rather than the actual resolved version after dependency resolution.

Detection:

• Direct dependency has been updated
• Lock file shows newer transitive version
• dotnet list package --include-transitive shows fixed version

Resolution:

# Verify actual version
dotnet list package --include-transitive | grep <package>

# If already fixed, suppress with evidence

Automation Scripts

Script 1: scan-branch.fsx

Purpose: Trigger CVE scan on specified branch Token Savings: ~500 tokens vs manual workflow triggering

Usage:

dotnet fsi .claude/skills/vulnerability-resolver/scripts/scan-branch.fsx [branch] [--cvss N] [--no-suppress]

Arguments:

• branch - Branch to scan (default: current)
• --cvss N - CVSS threshold (default: 7)
• --no-suppress - Disable suppression file

Script 2: parse-report.fsx

Purpose: Parse dependency-check HTML/JSON report and extract findings Token Savings: ~2000 tokens vs manual report reading

Usage:

dotnet fsi .claude/skills/vulnerability-resolver/scripts/parse-report.fsx <report-path>

Output: Structured list of CVEs with severity, package, and fix status

Script 3: create-suppression.fsx

Purpose: Generate properly formatted suppression XML entry Token Savings: ~300 tokens vs manual XML creation

Usage:

dotnet fsi .claude/skills/vulnerability-resolver/scripts/create-suppression.fsx \
  --cve CVE-2023-4914 \
  --reason "Package name confusion" \
  --details "Mono.Cecil is not Cecil SSG" \
  --reviewer "@username"

Integration Points

QA Tester Skill

Direction: To QA Tester Interaction: After dependency updates, request regression testing Trigger: Fix applied that updates package versions Protocol: "Dependency X updated to version Y to fix CVE-Z. Please run regression tests."

Release Manager Skill

Direction: To/From Release Manager Interaction:

• To: Verify no unresolved vulnerabilities before release
• From: Request vulnerability scan as part of release checklist Protocol: Pre-release gate includes clean vulnerability scan

AOT Guru Skill

Direction: To AOT Guru Interaction: Verify dependency updates don't break AOT compatibility Trigger: Package version update that might affect trimming/AOT Protocol: "Updated package X. Please verify AOT compatibility."

Review Capability

Review Scope

This skill proactively reviews security posture for:

1. Unresolved Vulnerabilities - CVEs not fixed or suppressed
2. Expiring Suppressions - Suppressions needing quarterly review
3. New Fix Availability - Previously unfixable CVEs now have fixes
4. Suppression Quality - Adequately documented suppressions

Review Triggers

Scheduled Review (Quarterly):

• Frequency: March, June, September, December
• Scope: All active suppressions
• Output: Quarterly security summary

On-Demand Review:

• Trigger: @skill vulnerability-resolver review
• Scope: Full security posture assessment
• Output: Comprehensive vulnerability report

Review Output Format

# Vulnerability Review Report
**Date:** YYYY-MM-DD
**Scope:** Full repository scan

## Summary
- Active Suppressions: N
- Expiring Soon: N
- Fixes Now Available: N
- New Vulnerabilities: N

## Findings

### Suppressions Requiring Attention
[List of suppressions expiring or with available fixes]

### Recommendations
1. Update X to version Y (CVE-Z now fixed)
2. Renew suppression for A (still valid false positive)
3. Review suppression for B (approaching 1 year old)

Quick Reference

Common Commands

# Trigger scan on current branch
gh workflow run cve-scanning.yml

# Trigger scan on specific branch
gh workflow run cve-scanning.yml --ref feature/my-branch

# Scan without suppressions (see everything)
gh workflow run cve-scanning.yml -f enable-suppressions=false

# Watch most recent scan
gh run list --workflow=cve-scanning.yml --limit 1
gh run watch $(gh run list --workflow=cve-scanning.yml --limit 1 --json databaseId -q '.[0].databaseId')

# Download report
gh run download <run-id> -n "Depcheck report"

# Check package versions
dotnet list package --include-transitive

# Search for package updates
dotnet package search <package-name> --take 5

Suppression File Location

.github/vuln-scanning/dependency-check-suppressions.xml

Key Files

.github/workflows/cve-scanning.yml                      # CVE scanning workflow
.github/vuln-scanning/dependency-check-suppressions.xml # Suppression definitions
Directory.Packages.props                                 # Package versions (central management)

Related Resources

Within This Project:

• README.md - Quick reference guide
• scripts/ - Automation scripts
• templates/ - Suppression and report templates

Project Guidance:

• AGENTS.md - Primary agent guidance
• Skills Reference - All available skills
• Requirements PRD

External Resources:

• OWASP Dependency-Check
• Suppression File Reference
• NVD - National Vulnerability Database
• GitHub Advisory Database

Last Updated: 2024-12-19 Version: 1.0.0 Status: alpha Maintainer: morphir-dotnet maintainers Issue: #281