Which versions of claude-jar are malicious?

The following npm versions of claude-jar are flagged malicious: 0.2.0. Treat any of these as compromised.

How do I remediate claude-jar if I installed it?

claude-jar is built to steal secrets, so assume every credential the build or runtime could read is compromised. Remove it from your project and lockfile, then rotate ALL exposed secrets — npm/registry tokens, cloud keys, CI/CD secrets, SSH keys, and any .env values — from a known-clean machine. Audit logs for unauthorized use of those credentials.

I already installed claude-jar — how do I know if it already compromised me?

If claude-jar was ever installed, its post-install/runtime payload may have already executed. O3's L7 egress monitoring and runtime eBPF sensors detect the credential exfiltration or command-and-control callback after install and block the malicious outbound channel, so you catch and contain the actual compromise — not just the presence of the package.

Is claude-jar part of a known attack campaign?

Yes — claude-jar is associated with the IN-MAL-2026-006752 campaign. Packages in the same campaign often share infrastructure and payloads, so check whether any related packages are also in your dependency tree.

How do I find claude-jar across my projects, lockfiles, and CI pipelines?

Scan your lockfiles (package-lock.json, pnpm-lock.yaml, yarn.lock, requirements.txt, poetry.lock, etc.) and build artifacts for claude-jar (version 0.2.0). O3 Security's supply-chain scanner checks every dependency against known-malicious package intelligence at install time and in CI, flagging claude-jar across your stack and pipelines.

Malicious package

claude-jarnpm

claude-jar is a confirmed malicious npm package (MAL-2026-5893) that steals credentials and exfiltrates sensitive data (malicious version 0.2.0). Do not install it — remove it immediately and rotate any exposed credentials.

Malicious code in claude-jar (npm)

MAL-2026-5893

Immediate action

Remove the package, then rotate any secrets the build/runtime could reach.

npm uninstall claude-jar

What this malware does

claude-jar 0.2.0 ships mcp-server/src/harvest.js, a fully-implemented credential-stealing module that enumerates other user accounts on the host (/Users/, /home/, C:\Users*) and reads ~/.aws/credentials, ~/.aws/config, ~/.ssh/id_rsa, ~/.ssh/id_ed25519, ~/.netrc, ~/.npmrc, ~/.git-credentials, ~/.gitconfig, ~/.config/gh/hosts.yml, ~/.config/gcloud/application_default_credentials.json, ~/.azure/credentials, ~/.kube/config, ~/.docker/config.json, IDE GlobalStorage GitHub auth, and copies+queries Chrome/Edge/Brave Cookies SQLite databases. Harvested tokens are validated against api.github.com and the npm registry. Execution is currently gated behind the CLAUDE_JAR_WHITEHAT_FULL_RECON=1 environment variable, but the harvester is fully functional code, not a stub. On first invocation of the CLI, src/cli.js:142-148 silently writes SessionStart/PreToolUse/PostToolUse hook handlers and an mcpServers entry into ~/.claude/settings.json and ~~/.cursor/mcp.json without a prompt; the registered launcher (~~/.claude-jar/mcp-server.mjs) loads hook-ingest.js → calibrator.js → harvest.js, ensuring the harvest path is reachable on every Claude Code tool call once the gate variable is set. Shipping a weaponizable, cross-user credential harvester wired into a persistent editor-hook trigger is a supply-chain risk regardless of the current gate: any future release, accidental env-var, or compromised maintainer account removes the gate and the harvester fires on the next tool call.

Malicious versions

1 flagged

0.2.0

Indicators of compromise (SHA-256)

6b5bea387a452218033b98c7f18b5c7aaa8890ed79930ee2ba550be312fc6498

Detection & response playbook

Credential / info stealer

Find it
Scan your lockfiles (package-lock.json, pnpm-lock.yaml, yarn.lock, requirements.txt, poetry.lock, etc.) and build artifacts for claude-jar (version 0.2.0). O3 Security's supply-chain scanner checks every dependency against known-malicious package intelligence at install time and in CI, flagging claude-jar across your stack and pipelines.
If you installed it — respond
claude-jar is built to steal secrets, so assume every credential the build or runtime could read is compromised. Remove it from your project and lockfile, then rotate ALL exposed secrets — npm/registry tokens, cloud keys, CI/CD secrets, SSH keys, and any .env values — from a known-clean machine. Audit logs for unauthorized use of those credentials.
Did it already run?
If claude-jar was ever installed, its post-install/runtime payload may have already executed. O3's L7 egress monitoring and runtime eBPF sensors detect the credential exfiltration or command-and-control callback after install and block the malicious outbound channel, so you catch and contain the actual compromise — not just the presence of the package.
How O3 protects you
O3 blocks claude-jar before install through its supply-chain scanner, and if it has already run, detects and severs the exfiltration or C2 callback at runtime through L7 egress monitoring and eBPF.

Frequently asked questions

No. claude-jar on npm has been identified as a malicious package (version 0.2.0 flagged). It should be removed immediately — do not install or keep it in your dependency tree.

Campaign

IN-MAL-2026-006752

References

npmjs.com

Credits

Amazon Inspector · finder

Detect & block this

O3 blocks claude-jar-class packages before install and in CI — and if it already ran, its runtime egress monitoring catches the credential exfiltration and severs the channel.

Malware detection Runtime egress monitoring

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