#!/usr/bin/env python3

"""
Project: BRS-KB (BRS XSS Knowledge Base)
Company: EasyProTech LLC (www.easypro.tech)
Dev: Brabus
Date: 2025-12-26 UTC
Status: Created
Telegram: https://t.me/EasyProTech

Knowledge Base: WebCodecs API XSS
"""

DETAILS = {
    "title": "Cross-Site Scripting (XSS) via WebCodecs API",
    "severity": "high",
    "cvss_score": 7.5,
    "cvss_vector": "CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:H/I:L/A:N",
    "reliability": "high",
    "cwe": ["CWE-79"],
    "owasp": ["A03:2021"],
    "tags": ["xss", "webcodecs", "video", "audio", "encoding", "chrome-94"],
    "description": """
WebCodecs API (Chrome 94+) provides low-level access to video/audio codecs. XSS vulnerabilities
occur when user input controls encoded data, codec configuration, or frame metadata without
validation.

SEVERITY: HIGH
Low-level codec access can lead to memory corruption and arbitrary code execution.
""",
    "attack_vector": """
WEBCODECS VIDEO FRAME DATA:
const decoder = new VideoDecoder({
  output: (frame) => {
    const canvas = document.createElement('canvas');
    canvas.getContext('2d').drawImage(frame, 0, 0);
    document.body.appendChild(canvas);  // XSS if frame contains malicious data
  },
  error: (e) => console.error(e)
});
decoder.configure({ codec: userInput });  // XSS if codec is controlled

WEBCODECS ENCODED CHUNK:
const chunk = new EncodedVideoChunk({
  type: 'key',
  timestamp: 0,
  data: new Uint8Array(userInput)  // XSS if data is malicious
});
decoder.decode(chunk);

WEBCODECS AUDIO DATA:
const decoder = new AudioDecoder({
  output: (audioData) => {
    const text = new TextDecoder().decode(audioData.data);
    document.body.innerHTML = text;  // XSS
  }
});
decoder.configure({ codec: userInput });

WEBCODECS CONFIGURATION:
decoder.configure({
  codec: 'vp8',
  width: userInput,  // XSS if width is controlled
  height: 480
});
""",
    "remediation": """
DEFENSE:

1. Validate all codec configurations
2. Sanitize frame data before rendering
3. Whitelist allowed codecs
4. Validate frame dimensions
5. Implement CSP

SAFE PATTERN:
const allowedCodecs = ['vp8', 'vp9', 'h264'];
if (!allowedCodecs.includes(userInput)) {
  throw new Error('Codec not allowed');
}
decoder.configure({ codec: userInput });

DIMENSION VALIDATION:
const maxWidth = 4096;
const maxHeight = 4096;
if (userInput > maxWidth || userInput > maxHeight) {
  throw new Error('Dimensions too large');
}

OWASP REFERENCES:
- CWE-79: Cross-site Scripting
- WebCodecs API Specification
""",
}
