<!-- Copyright (c) 2026 defconxt. All rights reserved. -->
<!-- Licensed under AGPL-3.0 — see LICENSE file for details. -->
---
name: implementing-input-validation
description: >-
  Design and implement robust input validation using allowlists, type checking, and context-aware sanitization.
domain: cybersecurity
subdomain: secure-coding
tags:
  - input-validation
  - sanitization
  - secure-coding
  - owasp
version: "1.0"
author: defconxt
license: AGPL-3.0
metadata:
  mitre-attack: ["T1190"]
---

# Implementing Input Validation

## Overview

Design and implement robust input validation using allowlists, type checking, and context-aware sanitization.

## Prerequisites

| Requirement | Install |
|---|---|
| Python 3.10+ | With pydantic |
| OWASP guidelines | Reference |
| Linting tools | Code analysis |

## Key Concepts

Input validation is the first defense against injection. Always
validate server-side. Prefer allowlists. Validate type, length,
range, format, and business rules.

## Quick Reference

```bash
from pydantic import BaseModel, constr
node agent.js validate --file app.py --framework pydantic
node agent.js audit --directory src/ --check input-validation
node agent.js report --directory src/
```

## Workflow

1. Identify input entry points
2. Define validation rules
3. Server-side validation
4. Client-side for UX
5. Test malformed inputs
6. Audit for bypass
7. Document rules

## Detection

```yaml
title: Input Validation Detection
id: 83d89874-9f55-40a5-8f79-67a7d732ad7a
status: experimental
description: Detects suspicious activity related to implementing input validation techniques in secure coding context
logsource:
  category: application
  product: webserver
detection:
  selection:
    EventType: error
  condition: selection
level: medium
tags:
  - attack.t1190
  - attack.initial_access
falsepositives:
  - Static analysis tools scanning source code repositories
```

## Verification

- Verify server-side validation
- Confirm allowlists
- Validate type/length checks
- Check no info leaks
- Verify consistency

## References

- OWASP Testing Guide — https://owasp.org/www-project-web-security-testing-guide/
- MITRE ATT&CK — https://attack.mitre.org/
- NIST SP 800-53 — https://csf.tools/reference/nist-sp-800-53/
