Security Scan

Analyze code changes (commits, PRs, diffs) using LLM-powered reasoning to detect security vulnerabilities. This skill reads code directly and applies patterns from the repository's threat model to identify issues across all STRIDE categories.

Adapted from Factory AI security-engineer plugin.

Session Phase Tracking

On entry, set the session phase:

PLUGIN_ROOT="${DROID_PLUGIN_ROOT:-${CLAUDE_PLUGIN_ROOT:-$(git rev-parse --show-toplevel 2>/dev/null || pwd)}}"
[ ! -d "$PLUGIN_ROOT/scripts" ] && PLUGIN_ROOT=$(ls -td ~/.claude/plugins/cache/nairon-flux/flux/*/ 2>/dev/null | head -1)
FLUXCTL="${PLUGIN_ROOT}/scripts/fluxctl"
$FLUXCTL session-phase set security_scan

On completion, reset:

$FLUXCTL session-phase set idle

When to Use This Skill

• PR review - Automated security scan on pull requests
• Pre-commit check - Scan staged changes before committing
• Branch comparison - Review security of feature branch changes
• After /flux:work - Verify task implementation is secure
• Code review assistance - Help reviewers spot security issues

Prerequisites

This skill requires:

1. Threat model - .flux/threat-model.md must exist
2. Security config - .flux/security-config.json for severity thresholds

IMPORTANT: If these files don't exist, you MUST generate them first using the flux-threat-model skill before proceeding with the security scan.

Inputs

The skill determines what to scan from the user's request:

Scan Type	How to Specify	Example
PR	"Scan PR #123"	Scan PR #456 for security vulnerabilities
Commit range	"Scan commits X..Y"	Scan commits abc123..def456
Single commit	"Scan commit X"	Scan commit abc123
Staged changes	"Scan staged changes"	Scan my staged changes for security issues
Uncommitted	"Scan uncommitted changes"	Scan working directory changes
Branch comparison	"Scan from X to Y"	Scan changes from main to feature-branch
Last N commits	"Scan last N commits"	Scan the last 3 commits

If no scope is specified, defaults to scanning staged changes.

Instructions

Follow these steps in order:

Step 1: Verify Prerequisites (Auto-Generate if Missing)

Try to read these files:

• .flux/threat-model.md
• .flux/security-config.json

If either file is missing or cannot be read:

1. Inform the user: "The security threat model doesn't exist yet. I'll generate it first - this may take a minute."
2. Invoke the flux-threat-model skill to analyze the repository and create both files
3. Once generation completes, continue with Step 2

Step 2: Get Changed Files

Based on the user's request, get the list of changed files and their diffs using git:

• For PRs: use gh pr diff
• For commits/ranges: use git diff or git show
• For staged changes: use git diff --cached

Read the full content of each changed file for context.

Step 3: Load Threat Model

Read .flux/threat-model.md and .flux/security-config.json to understand:

• The system's architecture and trust boundaries
• Known vulnerability patterns for this codebase
• Severity thresholds for findings

Step 4: Analyze for Vulnerabilities

For each changed file, systematically check for STRIDE threats:

S - Spoofing Identity

• Missing or weak authentication checks
• Session handling vulnerabilities
• Token/credential exposure in code
• Insecure cookie settings

T - Tampering with Data

• SQL Injection: String concatenation/interpolation in SQL queries
• Command Injection: User input in shell commands, eval(), exec()
• XSS: Unescaped user input in HTML/templates
• Mass Assignment: Blind assignment from request to model
• Path Traversal: User input in file paths without validation

R - Repudiation

• Missing audit logging for sensitive operations
• Insufficient error logging
• Log injection vulnerabilities

I - Information Disclosure

• IDOR: Direct object access without ownership verification
• Verbose error messages exposing internals
• Hardcoded secrets, API keys, credentials
• Sensitive data in logs or responses
• Debug endpoints exposed

D - Denial of Service

• Missing rate limiting on endpoints
• Unbounded resource consumption (file uploads, queries)
• Algorithmic complexity attacks (regex, sorting)
• Missing pagination on list endpoints

E - Elevation of Privilege

• Missing authorization checks on endpoints
• Role/permission bypass opportunities
• Privilege escalation through parameter manipulation

Step 5: Assess Each Finding

For each potential vulnerability:

1. Trace data flow: Follow user input from source to sink
2. Check for existing mitigations: Validation elsewhere? Framework protections?
3. Determine severity: CRITICAL, HIGH, MEDIUM, LOW
4. Assess confidence: HIGH (clear pattern), MEDIUM (possible), LOW (suspicious)

Step 6: Generate Report

Create .flux/security/security-findings.json with findings. Present summary to user with:

• Total findings by severity
• STRIDE category breakdown
• Files with issues
• Recommended fixes

CWE Reference

Common CWE mappings for findings:

Vulnerability Type	CWE
SQL Injection	CWE-89
Command Injection	CWE-78
XSS (Reflected/Stored)	CWE-79
Path Traversal	CWE-22
IDOR	CWE-639
Missing Authentication	CWE-306
Missing Authorization	CWE-862
Hardcoded Credentials	CWE-798
Sensitive Data Exposure	CWE-200
Mass Assignment	CWE-915

Gotchas

• This scan produces candidate findings, not final verdicts. Confirm data flow, framework protections, and existing mitigations before escalating severity.
• Avoid pattern matching in isolation. A scary sink without reachable untrusted input is usually noise.
• Keep the output actionable. Too many low-confidence findings train people to ignore the scan entirely.

References

• OWASP Top 10
• CWE Top 25