#!/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: SharedArrayBuffer XSS
"""

DETAILS = {
    "title": "Cross-Site Scripting (XSS) via SharedArrayBuffer",
    "severity": "critical",
    "cvss_score": 8.5,
    "cvss_vector": "CVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:C/C:H/I:H/A:H",
    "reliability": "medium",
    "cwe": ["CWE-79", "CWE-119"],
    "owasp": ["A03:2021"],
    "tags": ["xss", "sharedarraybuffer", "memory", "concurrency", "spectre", "critical"],
    "description": """
SharedArrayBuffer allows sharing memory between threads. XSS vulnerabilities occur when
user input controls buffer contents or indices, leading to memory corruption or arbitrary
code execution. Requires cross-origin isolation headers.

SEVERITY: CRITICAL
Can lead to memory corruption, Spectre attacks, and arbitrary code execution.
Requires Cross-Origin-Opener-Policy and Cross-Origin-Embedder-Policy headers.
""",
    "attack_vector": """
SHAREDARRAYBUFFER INDEX INJECTION:
const buffer = new SharedArrayBuffer(1024);
const view = new Int32Array(buffer);
view[userInput] = 0x41414141;  // XSS if index is out of bounds

SHAREDARRAYBUFFER DATA INJECTION:
const buffer = new SharedArrayBuffer(userInput.length);
const view = new Uint8Array(buffer);
for (let i = 0; i < userInput.length; i++) {
  view[i] = userInput.charCodeAt(i);  // Memory corruption
}

SHAREDARRAYBUFFER WITH WORKER:
const buffer = new SharedArrayBuffer(1024);
const worker = new Worker('data:text/javascript,' + userInput);  // XSS
worker.postMessage(buffer, [buffer]);

SHAREDARRAYBUFFER WITH ATOMICS:
const buffer = new SharedArrayBuffer(1024);
const view = new Int32Array(buffer);
Atomics.store(view, userInput, 0x41414141);  // Out of bounds

SHAREDARRAYBUFFER MEMORY LEAK:
const buffer = new SharedArrayBuffer(1024);
postMessage(buffer, '*');  // Leak to other origins
""",
    "remediation": """
DEFENSE:

1. Validate all array indices before access
2. Bounds check all buffer operations
3. Use TypedArray instead of direct buffer access
4. Implement cross-origin isolation headers
5. Restrict SharedArrayBuffer to trusted origins only

REQUIRED HEADERS:
Cross-Origin-Opener-Policy: same-origin
Cross-Origin-Embedder-Policy: require-corp

SAFE PATTERN:
function safeBufferAccess(buffer, index) {
  const view = new Int32Array(buffer);
  if (index < 0 || index >= view.length) {
    throw new RangeError('Index out of bounds');
  }
  return view[index];
}

VALIDATION:
const maxSize = 1024 * 1024;  // 1MB limit
if (userInput.length > maxSize) {
  throw new Error('Buffer too large');
}

OWASP REFERENCES:
- CWE-79: Cross-site Scripting
- CWE-119: Improper Restriction of Operations within Bounds
- SharedArrayBuffer Specification
- Spectre Mitigation
""",
}
