Which versions of cookie-sign are malicious?

The following npm versions of cookie-sign are flagged malicious: 2.3.5. Treat any of these as compromised.

How do I remediate cookie-sign if I installed it?

cookie-sign 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 cookie-sign — how do I know if it already compromised me?

If cookie-sign 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 cookie-sign part of a known attack campaign?

Yes — cookie-sign is associated with the IN-MAL-2026-009827 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 cookie-sign 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 cookie-sign (version 2.3.5). O3 Security's supply-chain scanner checks every dependency against known-malicious package intelligence at install time and in CI, flagging cookie-sign across your stack and pipelines.

Malicious package

cookie-signnpm

Malicious code in cookie-sign (npm) Remove it immediately and rotate any exposed credentials.

MAL-2026-10411

Immediate action

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

npm uninstall cookie-sign

What this malware does

The package presents itself as a cookie-signing / Express-middleware utility mimicking pino logger internals as cover, but its main entry spawns a detached child process running lib/initializeCaller.js. That script base64-decodes a hardcoded URL (https://ipcheck-hashed.vercel.app/api/auth/6c1d60d35852ef0c05df), POSTs the caller's entire process.env to it, and passes the HTTP response body to new Function('require', response.data) for immediate execution. This yields two attacker gains against the installer: exfiltration of all environment variables (which in CI/production typically hold cloud credentials, tokens, and secrets) and remote code execution in the installer's Node process using code returned by the attacker-controlled server. The C2 URL is base64-obfuscated and stored under a decoy DEV_API_KEY field, and the package name misrepresents its purpose.

Malicious versions

1 flagged

2.3.5

Indicators of compromise (SHA-256)

8ad03fe65b40f317c4f3dd1d4031b1ce3942432ccbb8d794c7b94c7de8566d0f

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 cookie-sign (version 2.3.5). O3 Security's supply-chain scanner checks every dependency against known-malicious package intelligence at install time and in CI, flagging cookie-sign across your stack and pipelines.
If you installed it — respond
cookie-sign 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 cookie-sign 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 cookie-sign 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. cookie-sign on npm has been identified as a malicious package (version 2.3.5 flagged). It should be removed immediately — do not install or keep it in your dependency tree.

Campaign

IN-MAL-2026-009827

References

npmjs.com

Credits

Amazon Inspector · finder

Detect & block this

O3 blocks cookie-sign-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