registry / cowork-harness / 0.22.0

cowork-harness@0.22.0

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 9d ago · by lpm-firewall-ai

No confirmed malicious attack surface. Risky primitives are aligned with a Claude Cowork test harness and are activated by explicit CLI commands, not package install or import.

Static reason

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

Trigger

User runs cowork-harness CLI commands such as run, skill, sync, hostloop, or decider options.

Impact

Can run local agent/container workflows and write harness run artifacts when invoked; no unconsented persistence, exfiltration, or lifecycle AI-agent control-surface mutation found.

Mechanism

User-invoked agent harness orchestration, local staging, and optional helper/container spawns.

Rationale

Static inspection found a package-aligned CLI harness with explicit user-invoked spawning, staging, network allowlist, and sync functionality, but no install-time/import-time execution, credential exfiltration, persistence, or unconsented writes to foreign AI-agent control surfaces. Scanner hints map to documented harness behavior and bundled helper/vendor files rather than concrete malicious behavior.

Evidence

package.jsondist/cli.jsdist/sync/cowork-sync.jsdist/runtime/hostloop.jsdist/runtime/hostloop-stage.jsdist/runtime/stage.jsdist/session.jsdist/decide/external-channel.js.claude/skills/cowork-harness/SKILL.md

Network endpoints6

api.claude.aimcp-proxy.anthropic.compreview.claude.aidownloads.claude.aiassets.claude.aipivot.claude.ai

Decision evidence

public snapshot

AI called this Clean at 91.0% confidence as Benign with low false-positive risk.

Evidence for block

Evidence against

package.json has no install/postinstall hook; prepublishOnly only runs npm run ci before publishing.
dist/cli.js is a user-invoked CLI entrypoint; no import-time execution beyond command parsing/imports observed.
dist/sync/cowork-sync.js npx @electron/asar use is limited to explicit sync maintenance command on local Claude Desktop app.asar.
dist/runtime/hostloop.js and dist/decide/external-channel.js spawn docker/agent/helper processes only for documented harness runs or operator-supplied decider commands.
dist/session.js/stage files write settings, skills, mcp.json into harness-managed run/config dirs and reject clobbering existing user config dirs.
.claude/skills/cowork-harness is bundled documentation/helper skill content, not lifecycle-installed into a foreign agent surface.

Behavioral surface

Source

ChildProcessCryptoEnvironmentVarsEvalFilesystemNetworkShell

Supply chain

HighEntropyStringsUrlStrings

ManifestNo manifest risk signals triggered.

scanned 74 file(s), 1.16 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 194-234javascript

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

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

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

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

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

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

200 writeDoneMarker(dir);

201 // 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 121-161javascript

121 flag(unknown, "gates: fcache decoded but NONE of the pinned gate IDs matched — gate IDs may have been re-keyed; update PINNED_GATES in cowork-sync.ts");

122 }

123 return {

124 appVersion,

125 agentVersion,

126 allowDomains,

127 networkMode,

128 requireFullVmSandbox,

129 asarFingerprint: fingerprint,

130 gates,

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/runtime/hostloop.jsView file

•matchType = previous_version_dangerous_delta matchedPackage = cowork-harness@0.20.0 matchedIdentity = npm:Y293b3JrLWhhcm5lc3M:0.20.0 similarity = 0.651 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/runtime/hostloop.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

214export function spawnChannel(cmd) { L215: // `shell: true` is INTENTIONAL, not an injection surface. `--decider-cmd` is OPERATOR-supplied — L216: // 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 · L214

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

141try { L142: execFileSync("npx", ["--yes", "@electron/asar", "extract", ASAR, tmp], { stdio: "ignore" }); L143: const bundle = readIf(join(tmp, ".vite/build/index.js")) ?? "";

High

Runtime Package Install

Package source invokes a package manager install command at runtime.

dist/sync/cowork-sync.jsView on unpkg · L141

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/runtime/hostloop.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/runtime/hostloop.jsView on unpkg

Findings

1 Critical4 High4 Medium6 Low

CriticalPrevious Version Dangerous Deltadist/runtime/hostloop.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 194-234javascript

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

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

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

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

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

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

200 writeDoneMarker(dir);

201 // 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 121-161javascript

121 flag(unknown, "gates: fcache decoded but NONE of the pinned gate IDs matched — gate IDs may have been re-keyed; update PINNED_GATES in cowork-sync.ts");

122 }

123 return {

124 appVersion,

125 agentVersion,

126 allowDomains,

127 networkMode,

128 requireFullVmSandbox,

129 asarFingerprint: fingerprint,

130 gates,

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/runtime/hostloop.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/runtime/hostloop.jsView on unpkg