registry / amicus / 2.1.0

amicus@2.1.0

Multi-model LLM Council + parallel AI window for Claude Code. Run structured council reviews across Gemini, GPT, DeepSeek and more — or fork a conversation to any model and fold the results back.

AI Security Review

scanned 3h ago · by lpm-firewall-ai

LPM blocks this version under the AI-agent control-surface policy. Install-time code mutates broad Claude agent control surfaces without an explicit user invocation. It plants Claude skills and registers a standing MCP server that later launches amicus via npx latest.

Static reason

High-risk behavior combination matched malicious policy.; source matched previously finalized malicious package; routed for review; previous stored version diff introduced dangerous source

Trigger

npm install / npm install -g package lifecycle postinstall

Impact

Claude Code/Desktop gains package-supplied skills and an auto-registered MCP server capable of spawning Amicus/OpenCode agent sessions from the user/home context.

Mechanism

unconsented lifecycle mutation of Claude skills and MCP configs

Policy narrative

On installation, the package runs scripts/postinstall.js. That script copies package-authored skills into the user's global Claude skills directory and registers an MCP server named amicus in Claude Code and Claude Desktop/Cowork configs, using npx -y amicus@latest mcp. The content is product-aligned, but the delivery is an npm lifecycle hook mutating foreign/broad AI-agent control surfaces without a separate user-invoked setup step.

Rationale

Static inspection confirms the scanner's critical finding: npm postinstall writes Claude skills and MCP registrations into user-level Claude control surfaces. Under the provided install-control-surface policy, unconsented lifecycle delivery into a foreign/broad agent surface is blockable even when product-aligned.

Evidence

package.jsonscripts/postinstall.jsskills/sidecar/SKILL.mdskills/second-opinion/SKILL.mdsrc/mcp-server.jssrc/mcp-tools.js~/.claude/skills/sidecar/SKILL.md~/.claude/skills/second-opinion/SKILL.md~/.claude/skills/second-opinion/COUNCIL-DESIGN.md~/.claude/skills/second-opinion/MODEL-NOTES.md~/.claude.json~/Library/Application Support/Claude/claude_desktop_config.json%APPDATA%/Claude/claude_desktop_config.json~/.config/claude/claude_desktop_config.json

Decision evidence

public snapshot

AI called this Malicious at 96.0% confidence as Dangerous Capability with low false-positive risk.

Evidence for policy block

package.json defines postinstall: node scripts/postinstall.js.
scripts/postinstall.js copies package skills into ~/.claude/skills/sidecar and ~/.claude/skills/second-opinion during npm install.
scripts/postinstall.js registers an amicus MCP server in Claude Code via claude mcp add-json or ~/.claude.json fallback.
scripts/postinstall.js writes Claude Desktop/Cowork claude_desktop_config.json with command npx -y amicus@latest mcp.
skills/sidecar/SKILL.md instructs Claude to run amicus/npx commands and use background launches; this is planted into Claude's global skill surface by lifecycle code.

Evidence against

Package purpose is openly agent/LLM sidecar and council tooling, and the planted skill/MCP content is product-aligned.
Postinstall has AMICUS_SKIP_POSTINSTALL=1 opt-out and tries to preserve existing amicus-shaped MCP env values.
Default Electron postinstall provisioning is cache-only; network prewarm requires AMICUS_PREFETCH_ELECTRON=1.
No credential exfiltration or destructive file deletion found in inspected source.

Behavioral surface

Source

ChildProcessCryptoDynamicRequireEnvironmentVarsFilesystemNetwork

Supply chain

HighEntropyStringsUrlStrings

ManifestNo manifest risk signals triggered.

scanned 146 file(s), 908 KB of source, external domains: aistudio.google.com, api.anthropic.com, api.deepseek.com, api.openai.com, console.anthropic.com, generativelanguage.googleapis.com, nodejs.org, openrouter.ai, platform.deepseek.com, platform.openai.com, www.w3.org

Source & flagged code

7 flagged

package.jsonView file

Lines 36-76json

36 },

37 "files": [

38 "bin/",

39 "src/",

40 "electron/",

41 "skills/",

42 "commands/",

43 ".claude-plugin/",

44 "CHANGELOG.md",

45 "scripts/postinstall.js",

46 "scripts/setup-hooks.js"

47 ],

48 "scripts": {

49 "start": "node --experimental-top-level-await --experimental-vm-modules bin/amicus.js",

50 "test": "jest",

51 "test:integration": "jest --testPathIgnorePatterns='\\.worktrees/' --testMatch='**/tests/**/*.integration.test.js'",

52 "test:all": "jest --testPathIgnorePatterns='/node_modules/' --testPathIgnorePatterns='\\.worktrees/' && node scripts/mark-test-passed.js",

53 "test:e2e:mcp": "jest tests/mcp-repomix-e2e.integration.test.js --testTimeout=180000 --forceExit",

54 "posttest": "node scripts/mark-test-passed.js",

55 "lint": "eslint src/",

56 "postinstall": "node scripts/postinstall.js",

High

Install Time Lifecycle Scripts

Package defines install-time lifecycle scripts.

package.jsonView on unpkg · L56

Medium

Ambiguous Install Lifecycle Script

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

package.jsonView on unpkg · L56

57 "test:thinking": "node scripts/benchmark-thinking.js",

58 "test:thinking:quick": "MODELS=gemini node scripts/benchmark-thinking.js",

59 "refresh-models": "node bin/amicus.js models --refresh",

60 "models:info": "node bin/amicus.js models",

61 "models:check": "node bin/amicus.js models --check",

62 "generate-icon": "node scripts/generate-icon.js",

63 "generate-docs": "node scripts/generate-docs.js",

64 "generate-docs:check": "node scripts/generate-docs.js --check",

65 "validate-docs": "node scripts/validate-docs.js --full",

66 "setup-hooks": "node scripts/setup-hooks.js",

67 "check:secrets": "node scripts/check-secrets.js --all",

68 "check:sizes": "node scripts/check-file-sizes.js --all",

69 "check:tarball": "node scripts/check-tarball-lifecycle.js"

70 },

71 "dependencies": {

72 "@modelcontextprotocol/sdk": "^1.27.0",

73 "@opencode-ai/sdk": "^1.1.36",

74 "dotenv": "^17.2.3",

75 "opencode-ai": "^1.2.20",

76 "tiktoken": "^1.0.0",

bin/amicus.jsView file

Lines 1-30javascript

1#!/usr/bin/env node

3/**

4 * Amicus CLI Entry Point

5 *

6 * Spec Reference: §4 CLI Interface

7 * Routes commands to appropriate handlers.

8 */

10// Load API keys from all sources: process.env > amicus .env > auth.json

11const { loadCredentials } = require('../src/utils/env-loader');

scripts/postinstall.jsView file

Lines 1-25javascript

1#!/usr/bin/env node

3/**

4 * Post-install script for amicus

5 *

6 * 1. Copies SKILL.md to ~/.claude/skills/sidecar/

7 * 2. Registers MCP server in Claude Code (~/.claude.json)

8 * 3. Registers MCP server in Claude Desktop/Cowork config

Critical

Ai Agent Control Hijack

Install-time source drops package-supplied AI-agent/MCP control files or instructions.

scripts/postinstall.jsView on unpkg · L5

9 */

src/sidecar/electron-install.jsView file

•matchType = normalized_sha256 matchedPackage = amicus@1.9.1 matchedPath = src/sidecar/electron-install.js matchedIdentity = npm:YW1pY3Vz:1.9.1 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.

src/sidecar/electron-install.jsView on unpkg

src/sidecar/unzip.jsView file

•matchType = normalized_sha256 matchedPackage = amicus@1.9.1 matchedPath = src/sidecar/unzip.js matchedIdentity = npm:YW1pY3Vz:1.9.1 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.

src/sidecar/unzip.jsView on unpkg

src/mcp-server.jsView file

•matchType = previous_version_dangerous_delta matchedPackage = amicus@1.8.1 matchedIdentity = npm:YW1pY3Vz:1.8.1 similarity = 0.508 summary = stored previous version shares package body but lacks this dangerous source file

High

Previous Version Dangerous Delta

This package version adds a dangerous source file absent from the previous stored version; route for source-aware review.

src/mcp-server.jsView on unpkg

Source & flagged code

7 flagged · loading source

package.jsonView file

•scripts.postinstall = node scripts/postinstall.js

High

Install Time Lifecycle Scripts

Package defines install-time lifecycle scripts.

package.jsonView on unpkg

•scripts.postinstall = node scripts/postinstall.js

Medium

Ambiguous Install Lifecycle Script

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

package.jsonView on unpkg

bin/amicus.jsView file

10// Load API keys from all sources: process.env > amicus .env > auth.json L11: const { loadCredentials } = require('../src/utils/env-loader'); L12: loadCredentials();

Medium

Dynamic Require

Package source references dynamic require/import behavior.

bin/amicus.jsView on unpkg · L10

scripts/postinstall.jsView file

5Install-time AI-agent control hijack evidence: L5: * L6: * 1. Copies SKILL.md to ~/.claude/skills/sidecar/ L7: * 2. Registers MCP server in Claude Code (~/.claude.json) L8: * 3. Registers MCP server in Claude Desktop/Cowork config ... L37: function skillsRoot() { L38: return path.join(os.homedir(), '.claude', 'skills'); L39: } ... L70: L71: if (!existing.mcpServers) { existing.mcpServers = {}; } L72: L73: const prev = existing.mcpServers[name]; L74: const nextConfig = (prev && isAmicusMcpConfig(prev)) ? { ...prev, ...config } : config; Payload evidence from skills/sidecar/SKILL.md: L41: 1. **ALWAYS launch amicus CLI commands with the Bash tool's `run_in_background: true`.** Never run `amicus start/resume/continue` in the foreground. L42: 2. **The fold summary returns on stdout** when the user clicks Fold in the GUI or the headless agent finishes. Use TaskOutput to read it when the background task completes. L43: 3. **For long or multi-line briefings, write them to a temp file and pass `--prompt-file <path>`** (mutually exclusive with `--prompt`; avoids shell-quoting hazards and argument-si... ... L82: **Step 1: Get an OpenRouter API key** L83: - Sign up at https://openrouter.ai …

Critical

Ai Agent Control Hijack

Install-time source drops package-supplied AI-agent/MCP control files or instructions.

scripts/postinstall.jsView on unpkg · L5

src/sidecar/electron-install.jsView file

High

Known Malware Source Similarity

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

src/sidecar/electron-install.jsView on unpkg

src/sidecar/unzip.jsView file

High

Known Malware Source Similarity

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

src/sidecar/unzip.jsView on unpkg

src/mcp-server.jsView file

High

Previous Version Dangerous Delta

This package version adds a dangerous source file absent from the previous stored version; route for source-aware review.

src/mcp-server.jsView on unpkg

Findings

1 Critical4 High5 Medium4 Low

CriticalAi Agent Control Hijackscripts/postinstall.js

HighInstall Time Lifecycle Scriptspackage.json

HighKnown Malware Source Similaritysrc/sidecar/electron-install.js

HighKnown Malware Source Similaritysrc/sidecar/unzip.js

HighPrevious Version Dangerous Deltasrc/mcp-server.js

MediumAmbiguous Install Lifecycle Scriptpackage.json

MediumDynamic Requirebin/amicus.js

MediumNetwork

MediumEnvironment Vars

MediumStructural Risk Force Deep Review

LowScripts Present

LowFilesystem

LowHigh Entropy Strings

LowUrl Strings

Source & flagged code

7 flagged

package.jsonView file

Lines 36-76json

36 },

37 "files": [

38 "bin/",

39 "src/",

40 "electron/",

41 "skills/",

42 "commands/",

43 ".claude-plugin/",

44 "CHANGELOG.md",

45 "scripts/postinstall.js",

46 "scripts/setup-hooks.js"

47 ],

48 "scripts": {

49 "start": "node --experimental-top-level-await --experimental-vm-modules bin/amicus.js",

50 "test": "jest",

51 "test:integration": "jest --testPathIgnorePatterns='\\.worktrees/' --testMatch='**/tests/**/*.integration.test.js'",

52 "test:all": "jest --testPathIgnorePatterns='/node_modules/' --testPathIgnorePatterns='\\.worktrees/' && node scripts/mark-test-passed.js",

53 "test:e2e:mcp": "jest tests/mcp-repomix-e2e.integration.test.js --testTimeout=180000 --forceExit",

54 "posttest": "node scripts/mark-test-passed.js",

55 "lint": "eslint src/",

56 "postinstall": "node scripts/postinstall.js",

High

Install Time Lifecycle Scripts

Package defines install-time lifecycle scripts.

package.jsonView on unpkg · L56

Medium

Ambiguous Install Lifecycle Script

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

package.jsonView on unpkg · L56

57 "test:thinking": "node scripts/benchmark-thinking.js",

58 "test:thinking:quick": "MODELS=gemini node scripts/benchmark-thinking.js",

59 "refresh-models": "node bin/amicus.js models --refresh",

60 "models:info": "node bin/amicus.js models",

61 "models:check": "node bin/amicus.js models --check",

62 "generate-icon": "node scripts/generate-icon.js",

63 "generate-docs": "node scripts/generate-docs.js",

64 "generate-docs:check": "node scripts/generate-docs.js --check",

65 "validate-docs": "node scripts/validate-docs.js --full",

66 "setup-hooks": "node scripts/setup-hooks.js",

67 "check:secrets": "node scripts/check-secrets.js --all",

68 "check:sizes": "node scripts/check-file-sizes.js --all",

69 "check:tarball": "node scripts/check-tarball-lifecycle.js"

70 },

71 "dependencies": {

72 "@modelcontextprotocol/sdk": "^1.27.0",

73 "@opencode-ai/sdk": "^1.1.36",

74 "dotenv": "^17.2.3",

75 "opencode-ai": "^1.2.20",

76 "tiktoken": "^1.0.0",

bin/amicus.jsView file

Lines 1-30javascript

1#!/usr/bin/env node

3/**

4 * Amicus CLI Entry Point

5 *

6 * Spec Reference: §4 CLI Interface

7 * Routes commands to appropriate handlers.

8 */

10// Load API keys from all sources: process.env > amicus .env > auth.json

11const { loadCredentials } = require('../src/utils/env-loader');

scripts/postinstall.jsView file

Lines 1-25javascript

1#!/usr/bin/env node

3/**

4 * Post-install script for amicus

5 *

6 * 1. Copies SKILL.md to ~/.claude/skills/sidecar/

7 * 2. Registers MCP server in Claude Code (~/.claude.json)

8 * 3. Registers MCP server in Claude Desktop/Cowork config

Critical

Ai Agent Control Hijack

Install-time source drops package-supplied AI-agent/MCP control files or instructions.

scripts/postinstall.jsView on unpkg · L5

9 */

src/sidecar/electron-install.jsView file

High

Known Malware Source Similarity

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

src/sidecar/electron-install.jsView on unpkg

src/sidecar/unzip.jsView file

High

Known Malware Source Similarity

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

src/sidecar/unzip.jsView on unpkg

src/mcp-server.jsView file

High

Previous Version Dangerous Delta

This package version adds a dangerous source file absent from the previous stored version; route for source-aware review.

src/mcp-server.jsView on unpkg