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 installed, its post-install payload may already have run. Removing the package does not undo that — check outbound connections and credential use from the install window onward.

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?

Search your lockfiles and build artifacts for cookie-sign (version 2.3.5).

Malicious package

cookie-signnpm

Advisory published Jul 13, 2026Updated Jul 13, 2026

cookie-sign is a confirmed malicious npm package (MAL-2026-10411) that steals credentials and exfiltrates sensitive data (malicious version 2.3.5). Do not install it — remove it immediately and rotate any exposed credentials.

Malicious code in cookie-sign (npm)

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
Search your lockfiles and build artifacts for cookie-sign (version 2.3.5).
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 installed, its post-install payload may already have run. Removing the package does not undo that — check outbound connections and credential use from the install window onward.

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

Explore

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