Patching & Remediation

Overview

The final critical step - our whitebox pentest is only complete with detailed code patches to remediate identified vulnerabilities.

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Patching Process

Apply Patches in Test Environment
             ↓
    Re-test PoC Exploit
             ↓
   Go Through Local Testing
             ↓
  Verify Original Functionality
             ↓
      Document Changes

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Patching

Before Patching

• Understand how vulnerability occurs

• Know exactly what needs to change

• Have test environment ready

Patch Testing Steps

1. Apply patch to test environment

2. Re-run PoC exploit → Should fail now

3. Re-do Local Testing → Ensure remediation at every stage

4. Verify functionality → Original features still work

5. Iterate if issues found

If Vulnerability Still Exists

Issue	Action
Payload not filtered properly	Update patch, test again
New bypass discovered	Strengthen patch
Different input vector works	Expand patch scope

Patch Requirements

• Vulnerability no longer exploitable

• All attack vectors covered

• Original functionality preserved

• No new issues introduced

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Reporting

Report Contents

Section	Description
Exploitation Steps	Detailed steps to reproduce
PoC Script Usage	How to run the exploit
Function Review	Analysis of each vulnerable function
Potential Issues	Other concerns identified
Code Patches	Exact changes required
Secure Coding Tips	Prevention guidance

Patch Documentation Template

## Vulnerability: [Name]

### Location
- File: `/src/controllers/auth.js`
- Function: `validateInput()`
- Lines: 45-52

### Original Code
```javascript
function validateInput(input) {
    return eval(input);  // VULNERABLE
}

Patched Code

function validateInput(input) {
    // Sanitize input before processing
    const sanitized = sanitizeInput(input);
    return JSON.parse(sanitized);  // SAFE
}

Changes Made

1. Removed use of eval()

2. Added input sanitization

3. Used safe JSON parsing instead

Verification Status

• PoC no longer works

• Local testing passed

• Functionality preserved

• Reviewed by senior engineer

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## Patch Verification Status

### Verified Patch

```markdown
### Verification Status: ✅ VERIFIED

The patch has been fully tested and verified as working:
- PoC exploit no longer succeeds
- All attack vectors blocked
- Original functionality maintained
- Tested in environment matching production

Unverified/Partial Patch

### Verification Status: ⚠️ PARTIAL

The patch affects multiple functions and requires further testing:
- Core vulnerability patched
- Some edge cases may need review
- Recommend senior engineer review before production
- Additional testing suggested for: [list areas]

---

Secure Coding Tips

Include in Report

General recommendations to prevent similar vulnerabilities:

Vulnerability Type	Secure Coding Tip
SQL Injection	Use parameterized queries
Command Injection	Avoid shell commands, use safe APIs
XSS	Encode output, use CSP
Code Injection	Never use eval(), use safe alternatives
Path Traversal	Validate and sanitize paths
SSRF	Whitelist allowed destinations

Example Recommendations

## Secure Coding Recommendations

### 1. Input Validation
- Validate all user input on server-side
- Use whitelisting over blacklisting
- Implement strict type checking

### 2. Output Encoding
- Encode output based on context (HTML, JS, URL)
- Use templating engines with auto-escaping

### 3. Least Privilege
- Database accounts with minimal permissions
- Service accounts with restricted access

### 4. Error Handling
- Don't expose stack traces to users
- Log errors securely for debugging

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Report Structure

# Whitebox Penetration Test Report

## Executive Summary
Brief overview of findings and risk level.

## Scope
What was tested and what was excluded.

## Methodology
Process followed (Code Review → Testing → PoC → Patching).

## Findings

### Finding 1: [Vulnerability Name]
- **Severity**: Critical/High/Medium/Low
- **Location**: File and function
- **Description**: What the vulnerability is
- **Impact**: What an attacker could achieve
- **Exploitation**: Step-by-step process
- **PoC**: How to use the exploit script
- **Patch**: Detailed code changes
- **Status**: Verified/Unverified

### Finding 2: ...

## Secure Coding Recommendations
General tips to prevent similar issues.

## Conclusion
Summary and next steps.

## Appendix
- Full PoC scripts
- Detailed code analysis
- Supporting evidence

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Checklist

Patching

• All patches applied to test environment

• PoC no longer works

• Local testing confirms remediation

• Original functionality preserved

• No new issues introduced

Documentation

• Exploitation steps documented

• PoC script usage explained

• Code patches detailed

• Changes clearly described

• Verification status noted

Report

• All findings included

• Severity ratings assigned

• Patches provided

• Secure coding tips included

• Ready for client delivery

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Tips

1. Test patches thoroughly - A broken patch is worse than none

2. Document everything - Developers need exact changes

3. Verify functionality - Don't break the application

4. Provide context - Explain why patch works

5. Think long-term - Tips prevent future issues