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local-mcp@3.0.386: Malicious npm security report (Block) | LPM Firewall

registry / local-mcp / 3.0.386

local-mcp@3.0.386

Let ChatGPT, Claude, Cursor & any MCP client actually use your Mac — read & reply to email, manage your calendar, text over iMessage, find files, work with Teams, Slack & Office. On your Mac, no API keys, free.

AI Security Review

scanned 26d ago · by lpm-firewall-ai

A global npm install automatically reconfigures detected AI clients to launch this package. It also downloads backend-directed native code and creates a persistent macOS tray service.

Static reason

High-risk behavior combination matched malicious policy.; source matched previously finalized malicious package; routed for review

Trigger

Installing the package globally with npm, unless CI or SKIP_SETUP is set.

Impact

The package can replace an existing MCP server, cause AI clients to execute its downloaded runtime, and persist a tray process across logins.

Mechanism

Automatic MCP configuration mutation, unsigned remote native payload installation, and LaunchAgent persistence.

Attack narrative

A global install invokes runSetup without an explicit setup command. It detects several unrelated AI clients, writes a launcher for local-mcp into their MCP configuration, and removes an office-mcp entry. Setup retrieves runtime metadata from the backend, accepts an HTTP(S) artifact URL from that response, extracts the archive, and the entrypoint executes the installed binary. On macOS it also writes a KeepAlive LaunchAgent. This creates an unconsented install-time path from npm installation to broad AI-agent control-surface changes, remote native payload execution, and persistence.

AI rationale

The automatic global postinstall performs broad foreign AI-client configuration mutation and installs backend-directed native code without integrity verification. Its persistence mechanism compounds the install-hook abuse into a concrete malicious supply-chain path.

Evidence

postinstall.jssetup.jsdownload.js~/Library/Application Support/Claude/claude_desktop_config.json~/.cursor/mcp.json~/.vscode/mcp.json

Source & flagged code

15 flagged · loading source

package.jsonView file

•scripts.postinstall = node postinstall.js

High

Install Time Lifecycle Scripts

Package defines install-time lifecycle scripts.

package.jsonView on unpkg

7scripts.postinstall = node postinstall.js Install-time code downloads an unverified remote native archive, stages it locally, activates an executable path, and exposes it to process execution. L7: * local-mcp setup → configura todos los clientes detectados L8: * local-mcp setup --all → configura todos sin preguntar L9: */ ... L13: const os = require('os') L14: const { execSync, execFileSync } = require('child_process') L15: const download = require('./download') ... L69: ' # curl telemetry — no Node dependency, fire-and-forget', L70: ` curl -sf --max-time 3 -X POST "https://${BACKEND_HOST}/install-event" \\`, L71: ' -H "Content-Type: application/json" \\', L72: ' -d "{\\\"stage\\\":\\\"node_too_old\\\",\\\"version\\\":\\\"$NODE_VER\\\"}" &>/dev/null &', L73: ' pr

High

Unverified Remote Native Payload Install

Install-time source downloads a native archive from a fixed external host without transport verification, extracts it, and installs an executable payload.

package.jsonView on unpkg · L7

•scripts.postinstall = node postinstall.js

Medium

Ambiguous Install Lifecycle Script

Install-time lifecycle script is not statically allowlisted and needs review.

package.jsonView on unpkg

download.jsView file

•Trigger-reachable chain: manifest.main -> index.js -> download.js Reachable file contains a blocking source-risk pattern.

Critical

Trigger Reachable Dangerous Capability

A package entrypoint or install-time lifecycle script reaches a source file with blocking dangerous behavior.

download.jsView on unpkg

12const os = require('os') L13: const { execFileSync, execSync } = require('child_process') L14:

High

Child Process

Package source references child process execution.

download.jsView on unpkg · L12

60// Only the win32 ladder reads/writes it: it's the side of the probe that can L61: // come up empty on a real machine (wmic gone, PowerShell blocked by policy), L62: // and consulting the same file the go-server already wrote/reads is what lets

High

Shell

Package source references shell execution.

download.jsView on unpkg · L60

7L8: const https = require('https') L9: const http = require('http') ... L12: const os = require('os') L13: const { execFileSync, execSync } = require('child_process') L14: ... L17: function extractTar(tarPath, destDir) { L18: const tarBin = process.platform === 'win32' L19: ? path.join(process.env.SystemRoot || 'C:\\Windows', 'System32', 'tar.exe') L20: : 'tar' ... L39: const CACHE_DIR = process.platform === 'win32' L40: ? path.join(process.env.LOCALAPPDATA || path.join(os.homedir(), 'AppData', 'Local'), 'local-mcp', 'bin')

download.js#virtual:normalized:round1View file

7L8: const https = require("https") L9: const http = require("http") ... L12: const os = require("os") L13: const { execFileSync, execSync } = require("child_process") L14: L15: // On Windows, Git-Bash"s tar interprets \"C:...\" paths as \"host:path\" (SSH syntax).\n// Use the native Windows tar.exe from System32 instead, which handles Win32 paths correctl... L16: // the caller would otherwise mask as "not yet available" (#1256).

Critical

Same File Env Network Execution

A single source file combines environment access, network access, and code or shell execution with blocking evidence.

download.js#virtual:normalized:round1View on unpkg · L7

•stage = ast_semantic_analysis; reason = ast_parse_error; limitedFiles = 4

High

Semantic Analysis Limited

A bounded semantic-analysis stage reached its safety limit; remaining detectors completed, but this package requires AI review.

download.js#virtual:normalized:round1View on unpkg

setup.jsView file

45// Write a .cmd wrapper that Claude Desktop can execute L46: fs.mkdirSync(cacheDir, { recursive: true }) L47: const cmdPath = path.join(cacheDir, 'lmcp-launch.cmd') ... L52: const script = `@echo off\r\n"${npxAbsPath}" -y local-mcp@latest\r\n` L53: fs.writeFileSync(cmdPath, script) L54: return cmdPath ... L59: try { L60: fs.mkdirSync(cacheDir, { recursive: true }) L61: const launcherPath = path.join(cacheDir, 'lmcp-launch.sh') ... L77: ].join('\n') + '\n' L78: fs.writeFileSync(launcherPath, script, { mode: 0o755 }) L79: return launcherPath

Critical

Ai Agent Control Hijack

Source creates an unconsented AI-agent control surface through install-time mutation or a default unauthenticated remote skill channel.

setup.jsView on unpkg · L45

1026if (!content.includes('local-mcp-server') && !content.includes('Local MCP')) return L1027: process.stderr.write('\n Migrating legacy server LaunchAgent to tray supervision...\n') L1028: // launchctl unload kills the running process AND prevents it from restarting L1029: try { execFileSync('launchctl', ['unload', plistPath], { stdio: 'pipe' }) } catch { /* may already be unloaded */ } L1030: try { fs.unlinkSync(plistPath) } catch { /* non-fatal */ } ... L1040: try { L1041: const https = require('https') L1042: const payload = {

High

Command Output Exfiltration

Source combines command execution, command-output handling, and outbound requests; review data flow before blocking.

setup.jsView on unpkg · L1026

1026Trigger-reachable command-output exfiltration chain: scripts.postinstall -> postinstall.js -> setup.js L1026: if (!content.includes('local-mcp-server') && !content.includes('Local MCP')) return L1027: process.stderr.write('\n Migrating legacy server LaunchAgent to tray supervision...\n') L1028: // launchctl unload kills the running process AND prevents it from restarting L1029: try { execFileSync('launchctl', ['unload', plistPath], { stdio: 'pipe' }) } catch { /* may already be unloaded */ } L1030: try { fs.unlinkSync(plistPath) } catch { /* non-fatal */ } ... L1040: try { L1041: const https = require('https') L1042: const payload = {

Source & flagged code

15 flagged

package.jsonView file

Lines 1-30json

1{

2 "name": "local-mcp",

3 "version": "3.0.386",

4 "description": "Let ChatGPT, Claude, Cursor & any MCP client actually use your Mac — read & reply to email, manage your calendar, text over iMessage, find files, work with Teams, Slack & Office. On your Mac, no API keys, free.",

5 "main": "index.js",

6 "bin": {

7 "local-mcp": "index.js"

8 },

9 "scripts": {

10 "postinstall": "node postinstall.js",

High

Install Time Lifecycle Scripts

Package defines install-time lifecycle scripts.

package.jsonView on unpkg · L10

Medium

Ambiguous Install Lifecycle Script

Install-time lifecycle script is not statically allowlisted and needs review.

package.jsonView on unpkg · L10

11 "test": "node --test test/*.test.js"

12 },

13 "files": [

14 "index.js",

15 "download.js",

16 "setup.js",

17 "postinstall.js",

18 "README.md"

19 ],

High

Unverified Remote Native Payload Install

Install-time source downloads a native archive from a fixed external host without transport verification, extracts it, and installs an executable payload.

package.jsonView on unpkg · L7

20 "engines": {

21 "node": ">=18"

22 },

23 "os": [

24 "darwin",

25 "linux",

26 "win32"

27 ],

28 "keywords": [

29 "mcp",

30 "model-context-protocol",

download.jsView file

Lines 1-32javascript

1'use strict'

2/**

3 * download.js — descarga y cachea el binario standalone de LMCP desde R2.

4 * El binario fue compilado con PyInstaller — no requiere Python instalado.

5 * Cache: ~/.local/share/local-mcp/bin/{version}/

6 */

7

8const https = require('https')

download.js#virtual:normalized:round1View file

7L8: const https = require("https") L9: const http = require("http") ... L12: const os = require("os") L13: const { execFileSync, execSync } = require("child_process") L14: L15: // On Windows, Git-Bash"s tar interprets \"C:...\" paths as \"host:path\" (SSH syntax).\n// Use the native Windows tar.exe from System32 instead, which handles Win32 paths correctl... L16: // the caller would otherwise mask as "not yet available" (#1256).

Critical

Same File Env Network Execution

A single source file combines environment access, network access, and code or shell execution with blocking evidence.

download.js#virtual:normalized:round1View on unpkg · L7

•stage = ast_semantic_analysis; reason = ast_parse_error; limitedFiles = 4

High

Semantic Analysis Limited

A bounded semantic-analysis stage reached its safety limit; remaining detectors completed, but this package requires AI review.

download.js#virtual:normalized:round1View on unpkg

setup.jsView file

Lines 1006-1046javascript

1006 req.on('error', () => resolve(''))

1007 req.on('timeout', () => { try { req.destroy() } catch {} resolve(''

Lines 40-80javascript

40 ? path.join(process.env.LOCALAPPDATA || path.join(os.homedir(), 'AppData', 'Local'), 'local-mcp', 'bin')

41 : path.join(os.homedir(), '.local', 'share', 'local-mcp', 'bin')

42

43const TRAY_DIR = process.platform === 'win32'

44 ? path.join(process.env.LOCALAPPDATA || path.join(os.homedir(), 'AppData', 'Local'), 'local-mcp', 'tray')

45 : path.join(os.homedir(), '.local', 'share', 'local-mcp', 'tray')

46

47// Install to ~/Applications (user-owned) to avoid macOS App Management TCC prompt.

48// /Applications requires kTCCServiceAppManagement permission which shows "node would like

49// to access data from other apps" on every tray update — confusing and unnecessary.

50// On Windows/Linux there is no tray app yet.

51const TRAY_APP = process.platform === 'darwin'

52 ? path.join(os.homedir(), 'Applications', 'LocalMCPTray.app')

53 : null

54

55// La instalación vieja que TRAY_APP supersede. Const (no literal suelto) porque el orden en

56// que se la retira es lo que arregla #2654 y los tests la inyectan.

57const SYSTEM_TRAY_APP = '/Applications/LocalMCPTray.app'

58

59// Mirror of go-server's CacheDir()/.machine-id (internal/machineid/machineid.go).

60// Only the win32 ladder reads/writes it: it's the side of the probe that can

61// come up empty on a real machine (wmic gone, PowerShell blocked by policy),

62// and consulting the same file the go-server already wrote/reads is what lets

High

Shell

Package source references shell execution.

download.jsView on unpkg · L60

63// the two sides converge on one id instead of the hostname-hash fallback.

64// cacheDir is a parameter (not read from the module-level CACHE_DIR directly)

65// for the same reason setup.js's _cloudTokenPath/_readCachedCloudToken/

66// _writeCloudToken take it explicitly: it lets tests point at a temp dir

67// instead of writing into the real user's cache.

68const WIN_MACHINE_ID_CACHE_NAME = '.machine-id'

69

70function _readWinMachineIdCache(cacheDir) {

71 try {

72 return fs.readFileSync(path.join(cacheDir, WIN_MACHINE_ID_CACHE_NAME), 'utf8').trim()

73 } catch {

74 return ''

75 }

76}

77

78function _writeWinMachineIdCache(cacheDir, id) {

79 try {

80 fs.mkdirSync(cacheDir, { recursive: true })