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local-mcp@3.0.380: Malicious npm security report (Block) | LPM Firewall

registry / local-mcp / 3.0.380

local-mcp@3.0.380

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 3h ago · by lpm-firewall-ai

A global install automatically changes detected third-party AI-client MCP configurations. It removes office-mcp, installs a launcher for local-mcp@latest, and obtains a remote executable that is run as an MCP server.

Static reason

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

Trigger

npm global installation triggers postinstall; later AI-client startup invokes the inserted MCP launcher.

Impact

It can replace an existing MCP server and grant a remotely supplied executable access through configured AI clients.

Mechanism

Automatic AI-client configuration takeover plus unverified remote binary download and execution.

Attack narrative

On global install, postinstall calls setup with all clients enabled. Setup detects AI clients, removes office-mcp from their configuration, installs local-mcp launch entries that resolve latest code, and writes a shell launcher. The runtime fetches an archive from the package backend or download host, extracts an executable without an integrity check, and spawns it for the MCP client. This is an unconsented install-time modification of broad third-party AI-agent control surfaces combined with remote executable delivery.

Rationale

The automatic lifecycle hook changes third-party AI-agent configurations, deletes a competing server entry, and establishes execution of an unverified remote binary. This is concrete install-hook abuse rather than ordinary user-invoked setup.

Evidence

package.jsonpostinstall.jssetup.jsdownload.jsindex.js~/.cursor/mcp.json~/.vscode/mcp.json~/.claude.json

Source & flagged code

16 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

7L8: const https = require('https') L9: const http = require('http') ... L12: const os = require('os') L13: const { execFileSync, execSync } = require('child_process') L14: ... L18: const tarBin = process.platform === 'win32' L19: ? path.join(process.env.SystemRoot || 'C:\\Windows', 'System32', 'tar.exe') L20: : 'tar'

Critical

Same File Env Network Execution

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

download.jsView on unpkg · L7

•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

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 = {

index.js#virtual:normalized:round1View file

•stage = ast_semantic_analysis; reason = ast_parse_error; limitedFiles = 3

High

Semantic Analysis Limited

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

index.js#virtual:normalized:round1View on unpkg

index.jsView file

•matchType = normalized_sha256 matchedPackage = local-mcp@3.0.379 matchedPath = index.js matchedIdentity = npm:bG9jYWwtbWNw:3.0.379 similarity = 1.000 summary = normalized source hash matched finalized malicious source

High

Known Malware Source Similarity

Source file is highly similar to a previously finalized malicious package; route for source-aware review.

index.jsView on unpkg

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 })