Initial commit : docs (specs, data-model, architecture, roadmap)
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Gwadaking
426
.claude/validate-commands.js
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426
.claude/validate-commands.js
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#!/usr/bin/env bun
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/**
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* Claude Code "Before Tools" Hook - Command Validation Script
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*
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* This script validates commands before execution to prevent harmful operations.
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* It receives command data via stdin and returns exit code 0 (allow) or 1 (block).
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*
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* Usage: Called automatically by Claude Code PreToolUse hook
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* Manual test: echo '{"tool_name":"Bash","tool_input":{"command":"rm -rf /"}}' | bun validate-command.js
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*/
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// Comprehensive dangerous command patterns database
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const SECURITY_RULES = {
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// Critical system destruction commands
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CRITICAL_COMMANDS: [
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"del",
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"format",
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"mkfs",
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"shred",
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"dd",
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"fdisk",
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"parted",
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"gparted",
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"cfdisk",
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],
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// Privilege escalation and system access
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PRIVILEGE_COMMANDS: [
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"sudo",
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"su",
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"passwd",
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"chpasswd",
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"usermod",
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"chmod",
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"chown",
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"chgrp",
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"setuid",
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"setgid",
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],
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// Network and remote access tools
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NETWORK_COMMANDS: [
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"nc",
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"netcat",
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"nmap",
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"telnet",
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"ssh-keygen",
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"iptables",
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"ufw",
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"firewall-cmd",
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"ipfw",
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],
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// System service and process manipulation
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SYSTEM_COMMANDS: [
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"systemctl",
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"service",
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"kill",
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"killall",
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"pkill",
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"mount",
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"umount",
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"swapon",
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"swapoff",
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],
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// Dangerous regex patterns
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DANGEROUS_PATTERNS: [
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// File system destruction - block rm -rf with absolute paths
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/rm\s+.*-rf\s*\/\s*$/i, // rm -rf ending at root directory
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/rm\s+.*-rf\s*\/\w+/i, // rm -rf with any absolute path
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/rm\s+.*-rf\s*\/etc/i, // rm -rf in /etc
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/rm\s+.*-rf\s*\/usr/i, // rm -rf in /usr
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/rm\s+.*-rf\s*\/bin/i, // rm -rf in /bin
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/rm\s+.*-rf\s*\/sys/i, // rm -rf in /sys
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/rm\s+.*-rf\s*\/proc/i, // rm -rf in /proc
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/rm\s+.*-rf\s*\/boot/i, // rm -rf in /boot
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/rm\s+.*-rf\s*\/home\/[^\/]*\s*$/i, // rm -rf entire home directory
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/rm\s+.*-rf\s*\.\.+\//i, // rm -rf with parent directory traversal
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/rm\s+.*-rf\s*\*.*\*/i, // rm -rf with multiple wildcards
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/rm\s+.*-rf\s*\$\w+/i, // rm -rf with variables (could be dangerous)
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/>\s*\/dev\/(sda|hda|nvme)/i,
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/dd\s+.*of=\/dev\//i,
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/shred\s+.*\/dev\//i,
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/mkfs\.\w+\s+\/dev\//i,
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// Fork bomb and resource exhaustion
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/:\(\)\{\s*:\|:&\s*\};:/,
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/while\s+true\s*;\s*do.*done/i,
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/for\s*\(\(\s*;\s*;\s*\)\)/i,
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// Command injection and chaining
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/;\s*(rm|dd|mkfs|format)/i,
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/&&\s*(rm|dd|mkfs|format)/i,
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/\|\|\s*(rm|dd|mkfs|format)/i,
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// Remote code execution
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/\|\s*(sh|bash|zsh|fish)$/i,
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/(wget|curl)\s+.*\|\s*(sh|bash)/i,
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/(wget|curl)\s+.*-O-.*\|\s*(sh|bash)/i,
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// Command substitution with dangerous commands
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/`.*rm.*`/i,
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/\$\(.*rm.*\)/i,
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/`.*dd.*`/i,
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/\$\(.*dd.*\)/i,
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// Sensitive file access
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/cat\s+\/etc\/(passwd|shadow|sudoers)/i,
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/>\s*\/etc\/(passwd|shadow|sudoers)/i,
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/echo\s+.*>>\s*\/etc\/(passwd|shadow|sudoers)/i,
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// Network exfiltration
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/\|\s*nc\s+\S+\s+\d+/i,
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/curl\s+.*-d.*\$\(/i,
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/wget\s+.*--post-data.*\$\(/i,
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// Log manipulation
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/>\s*\/var\/log\//i,
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/rm\s+\/var\/log\//i,
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/echo\s+.*>\s*~?\/?\.bash_history/i,
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// Backdoor creation
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/nc\s+.*-l.*-e/i,
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/nc\s+.*-e.*-l/i,
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/ncat\s+.*--exec/i,
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/ssh-keygen.*authorized_keys/i,
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// Crypto mining and malicious downloads
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/(wget|curl).*\.(sh|py|pl|exe|bin).*\|\s*(sh|bash|python)/i,
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/(xmrig|ccminer|cgminer|bfgminer)/i,
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// Hardware direct access
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/cat\s+\/dev\/(mem|kmem)/i,
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/echo\s+.*>\s*\/dev\/(mem|kmem)/i,
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// Kernel module manipulation
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/(insmod|rmmod|modprobe)\s+/i,
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// Cron job manipulation
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/crontab\s+-e/i,
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/echo\s+.*>>\s*\/var\/spool\/cron/i,
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// Environment variable exposure
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/env\s*\|\s*grep.*PASSWORD/i,
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/printenv.*PASSWORD/i,
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],
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// Paths that should never be written to
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PROTECTED_PATHS: [
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"/etc/",
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"/usr/",
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"/bin/",
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"/sbin/",
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"/boot/",
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"/sys/",
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"/proc/",
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"/dev/",
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"/root/",
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],
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};
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// Allowlist of safe commands (when used appropriately)
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const SAFE_COMMANDS = [
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"ls",
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"dir",
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"pwd",
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"whoami",
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"date",
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"echo",
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"cat",
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"head",
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"tail",
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"grep",
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"find",
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"wc",
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"sort",
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"uniq",
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"cut",
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"awk",
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"sed",
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"git",
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"npm",
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"pnpm",
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"node",
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"bun",
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"python",
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"pip",
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"cd",
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"cp",
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"mv",
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"mkdir",
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"touch",
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"ln",
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];
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class CommandValidator {
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constructor() {
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this.logFile = "/Users/melvynx/.claude/security.log";
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}
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/**
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* Main validation function
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*/
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validate(command, toolName = "Unknown") {
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const result = {
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isValid: true,
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severity: "LOW",
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violations: [],
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sanitizedCommand: command,
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};
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if (!command || typeof command !== "string") {
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result.isValid = false;
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result.violations.push("Invalid command format");
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return result;
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}
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// Normalize command for analysis
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const normalizedCmd = command.trim().toLowerCase();
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const cmdParts = normalizedCmd.split(/\s+/);
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const mainCommand = cmdParts[0];
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// Check against critical commands
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if (SECURITY_RULES.CRITICAL_COMMANDS.includes(mainCommand)) {
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result.isValid = false;
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result.severity = "CRITICAL";
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result.violations.push(`Critical dangerous command: ${mainCommand}`);
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}
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// Check privilege escalation commands
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if (SECURITY_RULES.PRIVILEGE_COMMANDS.includes(mainCommand)) {
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result.isValid = false;
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result.severity = "HIGH";
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result.violations.push(`Privilege escalation command: ${mainCommand}`);
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}
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// Check network commands
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if (SECURITY_RULES.NETWORK_COMMANDS.includes(mainCommand)) {
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result.isValid = false;
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result.severity = "HIGH";
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result.violations.push(`Network/remote access command: ${mainCommand}`);
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}
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// Check system commands
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if (SECURITY_RULES.SYSTEM_COMMANDS.includes(mainCommand)) {
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result.isValid = false;
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result.severity = "HIGH";
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result.violations.push(`System manipulation command: ${mainCommand}`);
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}
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// Check dangerous patterns
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for (const pattern of SECURITY_RULES.DANGEROUS_PATTERNS) {
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if (pattern.test(command)) {
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result.isValid = false;
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result.severity = "CRITICAL";
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result.violations.push(`Dangerous pattern detected: ${pattern.source}`);
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}
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}
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// Check for protected path access (but allow common redirections like /dev/null)
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for (const path of SECURITY_RULES.PROTECTED_PATHS) {
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if (command.includes(path)) {
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// Allow common safe redirections
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if (
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path === "/dev/" &&
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(command.includes("/dev/null") ||
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command.includes("/dev/stderr") ||
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command.includes("/dev/stdout"))
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) {
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continue;
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}
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result.isValid = false;
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result.severity = "HIGH";
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result.violations.push(`Access to protected path: ${path}`);
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}
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}
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// Additional safety checks
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if (command.length > 2000) {
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result.isValid = false;
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result.severity = "MEDIUM";
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result.violations.push("Command too long (potential buffer overflow)");
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}
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// Check for binary/encoded content
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if (/[\x00-\x08\x0B\x0C\x0E-\x1F\x7F-\xFF]/.test(command)) {
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result.isValid = false;
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result.severity = "HIGH";
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result.violations.push("Binary or encoded content detected");
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}
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return result;
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}
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/**
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* Log security events
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*/
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async logSecurityEvent(command, toolName, result, sessionId = null) {
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const timestamp = new Date().toISOString();
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const logEntry = {
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timestamp,
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sessionId,
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toolName,
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command: command.substring(0, 500), // Truncate for logs
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blocked: !result.isValid,
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severity: result.severity,
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violations: result.violations,
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source: "claude-code-hook",
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};
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try {
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// Write to log file
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const logLine = JSON.stringify(logEntry) + "\n";
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await Bun.write(this.logFile, logLine, { createPath: true, flag: "a" });
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// Also output to stderr for immediate visibility
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console.error(
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`[SECURITY] ${
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result.isValid ? "ALLOWED" : "BLOCKED"
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}: ${command.substring(0, 100)}`,
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);
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} catch (error) {
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console.error("Failed to write security log:", error);
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}
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}
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/**
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* Check if command matches any allowed patterns from settings
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*/
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isExplicitlyAllowed(command, allowedPatterns = []) {
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for (const pattern of allowedPatterns) {
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// Convert Claude Code permission pattern to regex
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// e.g., "Bash(git *)" becomes /^git\s+.*$/
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if (pattern.startsWith("Bash(") && pattern.endsWith(")")) {
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const cmdPattern = pattern.slice(5, -1); // Remove "Bash(" and ")"
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const regex = new RegExp(
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"^" + cmdPattern.replace(/\*/g, ".*") + "$",
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"i",
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);
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if (regex.test(command)) {
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return true;
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}
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}
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}
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return false;
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}
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}
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/**
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* Main execution function
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*/
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async function main() {
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const validator = new CommandValidator();
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try {
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// Read hook input from stdin
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const stdin = process.stdin;
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const chunks = [];
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for await (const chunk of stdin) {
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chunks.push(chunk);
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}
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const input = Buffer.concat(chunks).toString();
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if (!input.trim()) {
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console.error("No input received from stdin");
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process.exit(1);
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}
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// Parse Claude Code hook JSON format
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let hookData;
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try {
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hookData = JSON.parse(input);
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} catch (error) {
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console.error("Invalid JSON input:", error.message);
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process.exit(1);
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}
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const toolName = hookData.tool_name || "Unknown";
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const toolInput = hookData.tool_input || {};
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const sessionId = hookData.session_id || null;
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// Only validate Bash commands for now
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if (toolName !== "Bash") {
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console.log(`Skipping validation for tool: ${toolName}`);
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process.exit(0);
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}
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const command = toolInput.command;
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if (!command) {
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console.error("No command found in tool input");
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process.exit(1);
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}
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// Validate the command
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const result = validator.validate(command, toolName);
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// Log the security event
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await validator.logSecurityEvent(command, toolName, result, sessionId);
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// Output result and exit with appropriate code
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if (result.isValid) {
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console.log("Command validation passed");
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process.exit(0); // Allow execution
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} else {
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console.error(
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`Command validation failed: ${result.violations.join(", ")}`,
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);
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console.error(`Severity: ${result.severity}`);
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process.exit(2); // Block execution (Claude Code requires exit code 2)
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}
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} catch (error) {
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console.error("Validation script error:", error);
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// Fail safe - block execution on any script error
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process.exit(2);
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}
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}
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// Execute main function
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main().catch((error) => {
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console.error("Fatal error:", error);
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process.exit(2);
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});
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Block a user