Dfyx Code Security Review

dfyx-code-security-review

Skill by ara.so — Security Skills collection.

A professional code security audit skill designed for AI coding agents, implementing a five-phase standardized audit protocol with dual-track analysis (Sink-driven, Control-driven, Config-driven) to systematically discover and validate security vulnerabilities in source code.

Overview

dfyx_code_security_review provides expert-level white-box static analysis capabilities covering:

• 9 Languages: Java, Python, Go, PHP, JavaScript/Node.js, C/C++, .NET/C#, Ruby, Rust
• 10 Security Dimensions: Injection, Authentication, Authorization, Deserialization, File Operations, SSRF, Cryptography, Configuration, Business Logic, Supply Chain
• 14 Frameworks: Spring Boot, Django, Flask, FastAPI, Express, Koa, Gin, Laravel, Rails, ASP.NET Core, Rust Web, NestJS/Fastify, MyBatis, ProcessWire

Installation

Clone the repository and integrate with your AI coding agent:

# Clone the project
git clone https://github.com/EastSword/skill-dfyx_code_security_review.git

# For Claude Code
cp -r skill-dfyx_code_security_review ~/.claude/skills/

# Install Python dependencies (optional, for standalone scripts)
cd skill-dfyx_code_security_review
pip install -r requirements.txt

Core Methodology

Five-Phase Audit Protocol

Phase 1: Reconnaissance & Mapping (10%)
    ├─ Technology stack identification
    ├─ Architecture diagram generation
    └─ Attack surface enumeration

Phase 2: Parallel Pattern Matching (30%)
    ├─ Sink-driven scanning (dangerous functions)
    ├─ Control-driven scanning (missing security controls)
    └─ Config-driven scanning (misconfigurations)

Phase 3: Deep Taint Tracking & Practical Testing (40%)
    ├─ Data flow analysis
    ├─ Path-sensitive analysis
    └─ POC generation and verification

Phase 4: Validation & Attack Chain Construction (15%)
    ├─ Vulnerability validation
    ├─ Attack chain analysis
    └─ Exploitability assessment

Phase 5: Structured Reporting (5%)
    ├─ Vulnerability documentation
    ├─ Remediation guidance
    └─ Risk prioritization

Dual-Track Audit Model

Security Dimensions

Scan Modes

Usage Patterns

Basic Audit Request

Trigger an audit using natural language:

"Audit this codebase for security vulnerabilities"
"Perform a deep security review of this Spring Boot project"
"Find SQL injection and authentication issues"

The agent will respond with:

[MODE] deep
[RECON] 874 files, Spring Boot 1.5 + Shiro 1.6 + JPA + Freemarker
[PLAN] 5 Agents, D1-D10 coverage, estimated 125 turns
[SCOPE] Focus areas: Authentication, SQL Injection, Deserialization
Confirm to start audit? (yes/no)

Code Examples

SQL Injection Detection (Java)

Vulnerable Code:

// UserController.java
@GetMapping("/user/search")
public List<User> searchUser(@RequestParam String username) {
    String sql = "SELECT * FROM users WHERE username = '" + username + "'";
    return jdbcTemplate.query(sql, new UserRowMapper());
}

Detection Process:

1. [SINK] Identified dangerous sink: jdbcTemplate.query()
2. [SOURCE] Traced user input: @RequestParam username
3. [DATAFLOW] username → sql concatenation → jdbcTemplate.query()
4. [VALIDATION] No PreparedStatement, no input validation
5. [VULNERABILITY] SQL Injection (Critical)

Remediation:

// Fixed version
@GetMapping("/user/search")
public List<User> searchUser(@RequestParam String username) {
    String sql = "SELECT * FROM users WHERE username = ?";
    return jdbcTemplate.query(sql, new Object[]{username}, new UserRowMapper());
}

Command Injection Detection (Python)

Vulnerable Code:

# utils.py
import subprocess

def ping_host(host):
    cmd = f"ping -c 4 {host}"
    result = subprocess.call(cmd, shell=True)
    return result

Detection Process:

1. [SINK] Identified dangerous sink: subprocess.call(shell=True)
2. [SOURCE] Traced user input: host parameter
3. [DATAFLOW] host → f-string interpolation → subprocess.call()
4. [VALIDATION] No input sanitization, shell=True enables injection
5. [VULNERABILITY] Command Injection (Critical)

Remediation:

# Fixed version
import subprocess
import shlex

def ping_host(host):
    # Validate host format
    if not re.match(r'^[a-zA-Z0-9.-]+$', host):
        raise ValueError("Invalid host format")
    
    # Use list instead of shell
    result = subprocess.call(['ping', '-c', '4', host])
    return result

Authorization Bypass Detection (Node.js)

Vulnerable Code:

// routes/api.js
router.get('/admin/users', (req, res) => {
    // Missing authorization check
    const users = db.getAllUsers();
    res.json(users);
});

router.delete('/admin/user/:id', (req, res) => {
    // Missing authorization check
    db.deleteUser(req.params.id);
    res.json({success: true});
});

Detection Process:

1. [CONTROL] Enumerated admin endpoints: /admin/users, /admin/user/:id
2. [CHECK] Searched for middleware: auth.isAdmin, requireAdmin
3. [MISSING] No authorization middleware found
4. [VALIDATION] Direct access possible without admin role
5. [VULNERABILITY] Missing Authorization (High)

Remediation:

// Fixed version
const requireAdmin = (req, res, next) => {
    if (!req.user || req.user.role !== 'admin') {
        return res.status(403).json({error: 'Forbidden'});
    }
    next();
};

router.get('/admin/users', requireAdmin, (req, res) => {
    const users = db.getAllUsers();
    res.json(users);
});

router.delete('/admin/user/:id', requireAdmin, (req, res) => {
    db.deleteUser(req.params.id);
    res.json({success: true});
});

Deserialization Vulnerability (Java)

Vulnerable Code:

// DataProcessor.java
public Object processData(String base64Data) {
    byte[] data = Base64.getDecoder().decode(base64Data);
    ObjectInputStream ois = new ObjectInputStream(
        new ByteArrayInputStream(data)
    );
    return ois.readObject(); // Unsafe deserialization
}

Detection Process:

1. [SINK] Identified dangerous sink: ObjectInputStream.readObject()
2. [SOURCE] Traced user input: base64Data parameter
3. [DATAFLOW] base64Data → Base64 decode → readObject()
4. [GADGET] Checked classpath for known gadget chains (Commons-Collections)
5. [VULNERABILITY] Unsafe Deserialization → RCE (Critical)

Remediation:

// Fixed version using safe alternatives
public Map<String, Object> processData(String jsonData) {
    ObjectMapper mapper = new ObjectMapper();
    // Use JSON instead of Java serialization
    return mapper.readValue(jsonData, 
        new TypeReference<Map<String, Object>>(){});
}

// OR use whitelist if serialization is required
public Object processData(String base64Data) {
    byte[] data = Base64.getDecoder().decode(base64Data);
    ValidatingObjectInputStream vois = new ValidatingObjectInputStream(
        new ByteArrayInputStream(data)
    );
    // Whitelist allowed classes
    vois.accept(SafeClass.class, AnotherSafeClass.class);
    return vois.readObject();
}

Path Traversal Detection (PHP)

Vulnerable Code:

// download.php
<?php
$file = $_GET['file'];
$path = "/var/www/uploads/" . $file;
if (file_exists($path)) {
    header('Content-Type: application/octet-stream');
    readfile($path);
}
?>

Detection Process:

1. [SINK] Identified file operation: readfile()
2. [SOURCE] Traced user input: $_GET['file']
3. [DATAFLOW] $_GET['file'] → concatenation → readfile()
4. [VALIDATION] No path sanitization, allows "../" sequences
5. [ATTACK] Payload: ?file=../../../etc/passwd
6. [VULNERABILITY] Path Traversal (High)

Remediation:

// Fixed version
<?php
function sanitizeFilename($filename) {
    // Remove directory traversal sequences
    $filename = str_replace(['../', '..'], '', $filename);
    // Only allow alphanumeric, dash, underscore, dot
    $filename = preg_replace('/[^a-zA-Z0-9._-]/', '', $filename);
    return basename($filename);
}

$file = sanitizeFilename($_GET['file']);
$path = "/var/www/uploads/" . $file;

// Verify file is within allowed directory
$realpath = realpath($path);
if ($realpath && strpos($realpath, '/var/www/uploads/') === 0 && file_exists($realpath)) {
    header('Content-Type: application/octet-stream');
    readfile($realpath);
} else {
    http_response_code(404);
    echo "File not found";
}
?>

Standalone Script Usage

For command-line execution:

# Full scan
python scripts/code_scan.py /path/to/project --mode deep --output results.json

# Quick scan (CI/CD)
python scripts/code_scan.py /path/to/project --mode quick

# Focus on specific dimensions
python scripts/code_scan.py /path/to/project --dimensions D1,D2,D3

# Secret detection only
python scripts/secret_finder.py /path/to/project

# Dependency vulnerability check
python scripts/dependency_analyzer.py /path/to/project

# Generate report
python scripts/report_generator.py --input results.json --output report.md

Python API Usage

from scripts.code_scan import SecurityScanner
from scripts.data_flow_analyzer import DataFlowAnalyzer

# Initialize scanner
scanner = SecurityScanner(project_path='/path/to/project', mode='deep')

# Run scan
results = scanner.scan()

# Analyze specific vulnerability
dfa = DataFlowAnalyzer(project_path='/path/to/project')
flow = dfa.trace_taint(
    source='request.getParameter("id")',
    sink='jdbcTemplate.query(sql)',
    file='UserController.java'
)

# Generate report
scanner.generate_report(results, output_file='security_report.md')

Configuration

Environment Variables

# Set audit mode
export DFYX_AUDIT_MODE=deep  # quick|standard|deep

# Enable Docker verification
export DFYX_DOCKER_VERIFY=true

# Set report output format
export DFYX_REPORT_FORMAT=markdown  # markdown|json|html

# Configure parallel agents
export DFYX_AGENTS=5

# Set vulnerability severity threshold
export DFYX_MIN_SEVERITY=medium  # low|medium|high|critical

Custom Rules Configuration

Create custom_rules.yaml:

custom_rules:
  - id: CUSTOM_001
    name: "Internal API Key Exposure"
    pattern: 'INTERNAL_API_KEY\s*=\s*["'][^"']+["']'
    severity: critical
    language: [python, javascript]
    
  - id: CUSTOM_002
    name: "Unsafe Eval Usage"
    pattern: '\beval\s*\('
    severity: high
    language: [javascript, python]
    
  - id: CUSTOM_003
    name: "Missing CSRF Protection"
    pattern: '@PostMapping.*\n(?!.*@CsrfToken)'
    severity: medium
    language: [java]

Load custom rules:

python scripts/code_scan.py /path/to/project --rules custom_rules.yaml

Report Structure

Generated Report Sections

1. Executive Summary

   • Total vulnerabilities by severity
   • Critical findings summary
   • Risk score

2. Vulnerability Details

   • Code location with line numbers
   • Data flow diagram
   • Exploitation POC
   • Remediation code examples

3. Attack Chain Analysis

   • Multi-stage attack scenarios
   • Combined vulnerability exploitation

4. Dependency Analysis

   • Known CVEs in dependencies
   • Outdated package versions
   • License compliance

5. Secrets Detection

   • API keys, passwords in code
   • Hard-coded credentials
   • Environment leakage

Common Patterns

Pattern 1: SQL Injection in ORM

# Django vulnerable pattern
def search_users(request):
    query = request.GET.get('q')
    # Raw SQL with format string - VULNERABLE
    users = User.objects.raw(
        f"SELECT * FROM users WHERE name LIKE '%{query}%'"
    )
    return render(request, 'users.html', {'users': users})

# Fixed version
def search_users(request):
    query = request.GET.get('q')
    # Use parameterized query
    users = User.objects.raw(
        "SELECT * FROM users WHERE name LIKE %s",
        [f'%{query}%']
    )
    return render(request, 'users.html', {'users': users})

Pattern 2: JWT Authentication Bypass

// Vulnerable JWT validation
function verifyToken(token) {
    try {
        // Using 'none' algorithm vulnerable to bypass
        const decoded = jwt.decode(token, {complete: true});
        if (decoded.payload.admin) {
            return decoded.payload;
        }
    } catch(e) {
        return null;
    }
}

// Fixed version
function verifyToken(token) {
    try {
        // Verify signature with secret
        const decoded = jwt.verify(token, process.env.JWT_SECRET, {
            algorithms: ['HS256'] // Whitelist allowed algorithms
        });
        if (decoded.admin === true) {
            return decoded;
        }
    } catch(e) {
        return null;
    }
}

Pattern 3: IDOR in REST API

// Vulnerable controller
@GetMapping("/api/orders/{orderId}")
public Order getOrder(@PathVariable Long orderId) {
    // Missing authorization check - any user can access any order
    return orderService.findById(orderId);
}

// Fixed version
@GetMapping("/api/orders/{orderId}")
public Order getOrder(@PathVariable Long orderId, 
                      @AuthenticationPrincipal User currentUser) {
    Order order = orderService.findById(orderId);
    
    // Verify order belongs to current user
    if (!order.getUserId().equals(currentUser.getId()) && 
        !currentUser.isAdmin()) {
        throw new AccessDeniedException("Cannot access this order");
    }
    
    return order;
}

Pattern 4: XXE in XML Parsing

// Vulnerable XML parser
public Document parseXML(String xmlString) {
    DocumentBuilderFactory factory = DocumentBuilderFactory.newInstance();
    DocumentBuilder builder = factory.newDocumentBuilder();
    return builder.parse(new InputSource(new StringReader(xmlString)));
}

// Fixed version
public Document parseXML(String xmlString) {
    DocumentBuilderFactory factory = DocumentBuilderFactory.newInstance();
    
    // Disable external entities
    factory.setFeature("http://apache.org/xml/features/disallow-doctype-decl", true);
    factory.setFeature("http://xml.org/sax/features/external-general-entities", false);
    factory.setFeature("http://xml.org/sax/features/external-parameter-entities", false);
    factory.setExpandEntityReferences(false);
    
    DocumentBuilder builder = factory.newDocumentBuilder();
    return builder.parse(new InputSource(new StringReader(xmlString)));
}

Pattern 5: Race Condition in Balance Transfer

# Vulnerable transfer function
def transfer_money(from_account, to_account, amount):
    # Race condition: multiple concurrent transfers can overdraw
    balance = get_balance(from_account)
    if balance >= amount:
        time.sleep(0.1)  # Simulate processing delay
        decrease_balance(from_account, amount)
        increase_balance(to_account, amount)
        return True
    return False

# Fixed version with transaction lock
from django.db import transaction

@transaction.atomic
def transfer_money(from_account, to_account, amount):
    # Use select_for_update to lock row
    account = Account.objects.select_for_update().get(id=from_account)
    
    if account.balance >= amount:
        account.balance -= amount
        account.save()
        
        recipient = Account.objects.select_for_update().get(id=to_account)
        recipient.balance += amount
        recipient.save()
        return True
    return False

Troubleshooting

Issue: High False Positive Rate

Solution:

# Enable stricter validation
export DFYX_VALIDATION_MODE=strict

# Require POC generation for all findings
export DFYX_REQUIRE_POC=true

# Run with actual testing verification
python scripts/code_scan.py /path/to/project --verify-with-tests

Issue: Missing Framework-Specific Vulnerabilities

Solution:

# Enable framework-aware analysis
python scripts/code_scan.py /path/to/project --framework spring-boot

# Add framework-specific rules
python scripts/code_scan.py /path/to/project --rules resources/rules/spring_security_rules.yaml

Issue: Slow Scan Performance

Solution:

# Use quick mode for CI/CD
python scripts/code_scan.py /path/to/project --mode quick

# Increase parallel agents
export DFYX_AGENTS=10

# Exclude test files
python scripts/code_scan.py /path/to/project --exclude "**/test/**,**/tests/**"

Issue: Cannot Trace Complex Data Flow

Solution:

# Enable enhanced taint analysis
python scripts/code_scan.py /path/to/project --enhanced-taint

# Increase analysis depth
export DFYX_TAINT_DEPTH=10

# Manual data flow analysis
python scripts/data_flow_analyzer.py \
    --source "HttpServletRequest.getParameter" \
    --sink "Runtime.exec" \
    --file "VulnerableController.java"

Anti-Hallucination Mechanisms

The skill implements strict evidence requirements:

1. Code Evidence: Must provide exact file path and line numbers
2. Data Flow Path: Must trace complete source → sink path
3. POC Generation: Must demonstrate actual exploitability
4. Docker Verification: Optional containerized validation

# Enable all anti-hallucination checks
export DFYX_ANTI_HALLUCINATION=true
export DFYX_REQUIRE_EVIDENCE=true
export DFYX_DOCKER_VERIFY=true

Integration with CI/CD

GitHub Actions

name: Security Audit
on: [push, pull_request]

jobs:
  security-scan:
    runs-on: ubuntu-latest
    steps:
      - uses: actions/checkout@v3
      
      - name: Setup Python
        uses: actions/setup-python@v4
        with:
          python-version: '3.10'
      
      - name: Install dfyx
        run: |
          git clone https://github.com/EastSword/skill-dfyx_code_security_review.git
          cd skill-dfyx_code_security_review
          pip install -r requirements.txt
      
      - name: Run Security Scan
        run: |
          python skill-dfyx_code_security_review/scripts/code_scan.py . \
            --mode quick \
            --output results.json \
            --min-severity high
      
      - name: Upload Results
        uses: actions/upload-artifact@v3
        with:
          name: security-report
          path: results.json

GitLab CI

security-audit:
  stage: test
  image: python:3.10
  script:
    - git clone https://github.com/EastSword/skill-dfyx_code_security_review.git
    - cd skill-dfyx_code_security_review && pip install -r requirements.txt
    - cd .. && python skill-dfyx_code_security_review/scripts/code_scan.py . --mode quick
  artifacts:
    paths:
      - security_report.md
    expire_in: 1 week

Advanced Features

Attack Chain Analysis

The skill automatically identifies vulnerability combinations:

Attack Chain #1: Admin Account Takeover
├─ [Step 1] IDOR in /api/user/{id} (No authorization check)
├─ [Step 2] User enumeration via timing attack
├─ [Step 3] Password reset token prediction (weak randomness)
└─ [Impact] Full admin account compromise

POC:
1. Enumerate admin user ID: GET /api/user/1 (returns admin profile)
2. Trigger password reset: POST /api/reset-password {userId: 1}
3. Predict token using timestamp + user ID
4. Reset admin password: POST /api/confirm-reset {token: predicted}

Business Logic Vulnerability Detection

# Example: Discount code reuse vulnerability
@app.route('/apply-discount', methods=['POST'])
def apply_discount():
    code = request.json['code']
    # Missing: check if code already used by this user
    discount = DiscountCode.query.filter_by(code=code).first()
    if discount:
        session['discount'] = discount.percentage
        return {'success': True}

Detection:

[BUSINESS_LOGIC] Missing state validation
├─ Endpoint: /apply-discount
├─ Issue: No check for duplicate discount code usage
├─ Impact: User can apply same discount code multiple times
└─ Fix: Add user-code usage tracking table

WooYun Case Database

The skill includes 1000+ real-world vulnerability cases from WooYun (2010-2016):

# Search WooYun cases for similar vulnerabilities
python scripts/code_scan.py /path/to/project --with-wooyun-cases

# Output will reference similar cases
# "Similar to WooYun-2016-12345: Dedecms SQL Injection in article.php"

Best Practices

1. Pre-Audit Checklist

   • Ensure complete source code access
   • Identify all entry points (APIs, forms, file uploads)
   • Document authentication mechanisms
   • List third-party dependencies

2. During Audit

   • Confirm each finding with POC
   • Test in isolated environment
   • Document data flow with diagrams
   • Prioritize by exploitability + impact

3. Post-Audit

   • Validate all remediation code
   • Re-scan after fixes
   • Add to regression test suite
   • Update threat model

License

MIT License - Free for security research and educational purposes only.

Resources

• Documentation: resources/knowledge/ (13 knowledge base documents)
• Rule Sets: resources/rules/ (vulnerability detection patterns)
• WooYun Cases: resources/wooyun/wooyun_cases_by_vulnerability_type.md
• Templates: templates/report-templates/ (standard report formats)
• Examples: examples/ (audit examples and POCs)

For issues or contributions, visit: https://github.com/EastSword/skill-dfyx_code_security_review