registry / cowork-harness / 1.0.0

cowork-harness@1.0.0

Scriptable, CI-friendly harness for Claude Cowork's runtime contract for testing skills across scenarios — same agent, mounts, egress allowlist, permission protocol, and sandbox limitations.

AI Security Review

scanned 2h ago · by lpm-firewall-ai

Install-time prepare changes the current Git repository's hooksPath to a package-relative `.githooks` directory. At runtime, explicit CLI commands can launch a Claude agent, decider helper, containers, or a provisioned VM for testing.

Static reason

One or more suspicious static signals were detected.; previous stored version diff introduced dangerous source

Trigger

npm install executes prepare; user invokes harness run, sync, decider, or microVM modes.

Impact

Repository hook configuration is modified; user-invoked runs have deliberate process execution and network-capable VM provisioning.

Mechanism

prepare-time Git configuration plus explicit agent/sandbox orchestration

Rationale

Source inspection does not support a malicious verdict, but the install-time Git configuration mutation and intentionally broad agent/sandbox execution capability warrant a warning under the stated lifecycle and dangerous-capability policy.

Evidence

package.jsondist/decide/external-channel.jsdist/runtime/protocol.jsdist/runtime/lima.jsdist/dotenv.jsdist/redact.js.claude/skills/cowork-harness/scripts/_vendor/yaml/scanner.py.githooks

Network endpoints2

downloads.claude.ai/claude-code-releases/${version}/manifest.jsondeb.nodesource.com/setup_22.x

Decision evidence

public snapshot

AI called this Suspicious at 84.0% confidence as Dangerous Capability with medium false-positive risk.

Evidence for warning

package.json: prepare runs `git config core.hooksPath .githooks || true` during install.
dist/decide/external-channel.js spawns an operator-supplied `--decider-cmd` with `shell:true`.
dist/runtime/lima.js provisions an explicitly launched VM with curl, npm, and pip installs.
dist/runtime/protocol.js launches the configured `claude` agent binary for harness runs.

Evidence against

package.json has no preinstall, install, or postinstall hook; prepublishOnly is publish-time CI.
No source evidence of credential exfiltration, stealth payload loading, or package-controlled data upload.
The shell helper is explicitly supplied by the invoking operator, not package data.
The flagged vendor file is readable Python YAML-scanner source, not a hidden executable payload.
dist/dotenv.js and dist/redact.js document local credential handling and redaction rather than transmission.

Behavioral surface

Source

ChildProcessCryptoEnvironmentVarsEvalFilesystemNetworkShell

Supply chain

HighEntropyStringsUrlStrings

ManifestNo manifest risk signals triggered.

scanned 96 file(s), 1.88 MB of source, external domains: api.anthropic.com, cloud-images.ubuntu.com, deb.nodesource.com, downloads.claude.ai, example.com, nodejs.org, raw.githubusercontent.com

Source & flagged code

7 flagged

dist/decide/external-channel.jsView file

Lines 1-24javascript

1import { warn, envPositiveNumber } from "../io.js";

2import { mkdirSync, readdirSync, existsSync, readFileSync, writeFileSync, renameSync, rmSync } from "node:fs";

3import { join } from "node:path";

4import readline from "node:readline";

5import { spawn } from "node:child_process";

6/** A sequential line reader over a stream that buffers across chunk boundaries (readline does this). */

High

Child Process

Package source references child process execution.

dist/decide/external-channel.jsView on unpkg · L4

7function lineReader(input) {

8 const rl = readline.createInterface({ input, crlfDelay: Infinity });

9 const queue = [];

10 const waiters = [];

11 let done = false;

12 rl.on("line", (l) => (waiters.length ? waiters.shift()(l) : queue.push(l)));

13 rl.on("close", () => {

14 done = true;

15 while (waiters.length)

16 waiters.shift()(null);

17 });

18 return {

19 next: () => new Promise((resolve) => {

20 if (queue.length)

21 return resolve(queue.shift());

22 if (done)

23 return resolve(null);

24 waiters.push(resolve);

Lines 196-236javascript

196 // remove the exit listener registered for this channel so repeated fileChannel() calls

197 // in one process don't accumulate listeners past the MaxListenersExceededWarning threshold.

198 process.removeListener("exit", exitHandler);

199 // That exit listener was the only writer of done.json — a long-lived embedder that close()s but

200 // keeps running must still release a `gates --follow` watcher. Write the marker here too (idempotent,

201 // and not matched by the cleanup globs below, so it survives).

202 writeDoneMarker(dir);

203 // Best-effort remove processed files on close (req/resp + .done markers + tmp).

dist/decide/decider.jsView file

Lines 967-1007javascript

967}

968function evalPredicate(expr, input) {

969 // (additive): expose the whole input object as `input` so predicates can reach keys that are not

970 // valid JS identifiers — `input["file-path"]`, `input["foo.bar"]`. We ALSO keep binding each input key as

971 // a bare parameter (`command.includes(...)`), the form used by shipped example scenarios and the docs —

972 // dropping it would silently false-deny those on first run. Only identifier-shaped keys can be bound as a

973 // bare parameter (a key like `file-path` is not a legal parameter name and would fail `new Function`

dist/sync/cowork-sync.jsView file

Lines 199-239javascript

199 visited.add(p);

200 const content = readFileSync(p, "utf8");

201 out.set(p.slice(p.lastIndexOf("/") + 1), content);

202 for (const m

python/conftest.pyView file

•path = python/conftest.py kind = build_helper sizeBytes = 544 magicHex = [redacted]

Medium

Ships Build Helper

Package ships non-JavaScript build or shell helper files.

python/conftest.pyView on unpkg

.claude/skills/cowork-harness/scripts/_vendor/yaml/scanner.pyView file

•path = .claude/skills/cowork-harness/scripts/_vendor/yaml/scanner.py kind = payload_in_excluded_dir sizeBytes = 51279 magicHex = [redacted]

High

Payload In Excluded Dir

Package hides binary, compressed, or executable-looking payloads in test/fixture/hidden paths.

.claude/skills/cowork-harness/scripts/_vendor/yaml/scanner.pyView on unpkg

dist/agent/session.jsView file

•matchType = previous_version_dangerous_delta matchedPackage = cowork-harness@0.32.0 matchedIdentity = npm:Y293b3JrLWhhcm5lc3M:0.32.0 similarity = 0.933 summary = stored previous version shares package body but lacks this dangerous source file

Critical

Previous Version Dangerous Delta

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

dist/agent/session.jsView on unpkg

Source & flagged code

7 flagged · loading source

dist/decide/external-channel.jsView file

4import readline from "node:readline"; L5: import { spawn } from "node:child_process"; L6: /** A sequential line reader over a stream that buffers across chunk boundaries (readline does this). */

High

Child Process

Package source references child process execution.

dist/decide/external-channel.jsView on unpkg · L4

216export function spawnChannel(cmd) { L217: // `shell: true` is INTENTIONAL, not an injection surface. `--decider-cmd` is OPERATOR-supplied — L218: // the same trust class as the harness process itself (whoever runs the harness wrote this string). Shell

High

Shell

Package source references shell execution.

dist/decide/external-channel.jsView on unpkg · L216

dist/decide/decider.jsView file

987try { L988: fn = new Function(...params, `"use strict"; return (${expr});`); L989: }

Low

Eval

Package source references a known benign dynamic code generation pattern.

dist/decide/decider.jsView on unpkg · L987

dist/sync/cowork-sync.jsView file

219try { L220: execFileSync("npx", ["--yes", "@electron/asar", "extract", ASAR, tmp], { stdio: "ignore" }); L221: const bundleFiles = readMainBundleFiles(tmp);

High

Runtime Package Install

Package source invokes a package manager install command at runtime.

dist/sync/cowork-sync.jsView on unpkg · L219

python/conftest.pyView file

•path = python/conftest.py kind = build_helper sizeBytes = 544 magicHex = [redacted]

Medium

Ships Build Helper

Package ships non-JavaScript build or shell helper files.

python/conftest.pyView on unpkg

.claude/skills/cowork-harness/scripts/_vendor/yaml/scanner.pyView file

•path = .claude/skills/cowork-harness/scripts/_vendor/yaml/scanner.py kind = payload_in_excluded_dir sizeBytes = 51279 magicHex = [redacted]

High

Payload In Excluded Dir

Package hides binary, compressed, or executable-looking payloads in test/fixture/hidden paths.

.claude/skills/cowork-harness/scripts/_vendor/yaml/scanner.pyView on unpkg

dist/agent/session.jsView file

Critical

Previous Version Dangerous Delta

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

dist/agent/session.jsView on unpkg

Findings

1 Critical4 High4 Medium6 Low

CriticalPrevious Version Dangerous Deltadist/agent/session.js

HighChild Processdist/decide/external-channel.js

HighShelldist/decide/external-channel.js

HighRuntime Package Installdist/sync/cowork-sync.js

HighPayload In Excluded Dir.claude/skills/cowork-harness/scripts/_vendor/yaml/scanner.py

MediumNetwork

MediumEnvironment Vars

MediumShips Build Helperpython/conftest.py

MediumStructural Risk Force Deep Review

LowNon Install Lifecycle Scripts

LowScripts Present

LowEvaldist/decide/decider.js

LowFilesystem

LowHigh Entropy Strings

LowUrl Strings

Source & flagged code

7 flagged

dist/decide/external-channel.jsView file

Lines 1-24javascript

1import { warn, envPositiveNumber } from "../io.js";

2import { mkdirSync, readdirSync, existsSync, readFileSync, writeFileSync, renameSync, rmSync } from "node:fs";

3import { join } from "node:path";

4import readline from "node:readline";

5import { spawn } from "node:child_process";

6/** A sequential line reader over a stream that buffers across chunk boundaries (readline does this). */

High

Child Process

Package source references child process execution.

dist/decide/external-channel.jsView on unpkg · L4

7function lineReader(input) {

8 const rl = readline.createInterface({ input, crlfDelay: Infinity });

9 const queue = [];

10 const waiters = [];

11 let done = false;

12 rl.on("line", (l) => (waiters.length ? waiters.shift()(l) : queue.push(l)));

13 rl.on("close", () => {

14 done = true;

15 while (waiters.length)

16 waiters.shift()(null);

17 });

18 return {

19 next: () => new Promise((resolve) => {

20 if (queue.length)

21 return resolve(queue.shift());

22 if (done)

23 return resolve(null);

24 waiters.push(resolve);

Lines 196-236javascript

196 // remove the exit listener registered for this channel so repeated fileChannel() calls

197 // in one process don't accumulate listeners past the MaxListenersExceededWarning threshold.

198 process.removeListener("exit", exitHandler);

199 // That exit listener was the only writer of done.json — a long-lived embedder that close()s but

200 // keeps running must still release a `gates --follow` watcher. Write the marker here too (idempotent,

201 // and not matched by the cleanup globs below, so it survives).

202 writeDoneMarker(dir);

203 // Best-effort remove processed files on close (req/resp + .done markers + tmp).

dist/decide/decider.jsView file

Lines 967-1007javascript

967}

968function evalPredicate(expr, input) {

969 // (additive): expose the whole input object as `input` so predicates can reach keys that are not

970 // valid JS identifiers — `input["file-path"]`, `input["foo.bar"]`. We ALSO keep binding each input key as

971 // a bare parameter (`command.includes(...)`), the form used by shipped example scenarios and the docs —

972 // dropping it would silently false-deny those on first run. Only identifier-shaped keys can be bound as a

973 // bare parameter (a key like `file-path` is not a legal parameter name and would fail `new Function`

dist/sync/cowork-sync.jsView file

Lines 199-239javascript

199 visited.add(p);

200 const content = readFileSync(p, "utf8");

201 out.set(p.slice(p.lastIndexOf("/") + 1), content);

202 for (const m

python/conftest.pyView file

•path = python/conftest.py kind = build_helper sizeBytes = 544 magicHex = [redacted]

Medium

Ships Build Helper

Package ships non-JavaScript build or shell helper files.

python/conftest.pyView on unpkg

.claude/skills/cowork-harness/scripts/_vendor/yaml/scanner.pyView file

•path = .claude/skills/cowork-harness/scripts/_vendor/yaml/scanner.py kind = payload_in_excluded_dir sizeBytes = 51279 magicHex = [redacted]

High

Payload In Excluded Dir

Package hides binary, compressed, or executable-looking payloads in test/fixture/hidden paths.

.claude/skills/cowork-harness/scripts/_vendor/yaml/scanner.pyView on unpkg

dist/agent/session.jsView file

Critical

Previous Version Dangerous Delta

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

dist/agent/session.jsView on unpkg