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Malicious package

cat-sis2go-utilsnpm

Advisory published Updated

cat-sis2go-utils is a confirmed malicious npm package (MAL-2026-16071) that steals credentials and exfiltrates sensitive data (malicious versions 99.0.0, 99.1.0). Do not install it — remove it immediately and rotate any exposed credentials.

Malicious code in cat-sis2go-utils (npm)

MAL-2026-16071
Immediate action
Remove the package, then rotate any secrets the build/runtime could reach.
npm uninstall cat-sis2go-utils

What this malware does

cat-sis2go-utils is a dependency-confusion package published against the SIS2GO namespace, with versions inflated to 99.0.0 and 99.1.0. It ships no library code (index.js is an 87-byte stub), and package.json declares both preinstall and postinstall running node scripts/run.js, so the payload executes twice during npm install before any application code. The script resolves a DNS canary and POSTs to a webhook.site collector; 99.1.0 additionally sends os.userInfo().username and os.hostname(). The author labels this a PoC, but the beacon fires on any install that resolves the package and exfiltrates a username usable for follow-on attacks, and dependency-confusion packages require incident response even when trivial.

Package [email protected] declares both preinstall and postinstall lifecycle hooks in package.json that execute scripts/run.js on every npm install. The script unconditionally issues a DNS lookup against d22d92dc-84e5-4b58-8cd6-75bf1ac452c7.dnshook.site and POSTs a JSON beacon containing the installer's hostname and process context to https://webhook.site/d22d92dc-84e5-4b58-8cd6-75bf1ac452c7. The package description self-identifies as a dependency-confusion PoC, and the 99.0.0 version is consistent with a resolution-winning squat targeting an internal package name. Installing the package results in arbitrary code execution on the installer host and fingerprints the machine to third-party out-of-band collectors under the operator's control.

Malicious versions

2 flagged
99.0.099.1.0

Indicators of compromise (SHA-256)

205b59e55b3e3474f6b5de7471c11e7095e019a9f1e682083b34eeb7dddd5c3f
ad357542f3dd0e1b598ef36d440b1868ac28c6889226864bf799b2f7b6bf5e91

Detection & response playbook

Credential / info stealer
  1. Find it

    Search your lockfiles and build artifacts for cat-sis2go-utils (2 malicious versions).

  2. If you installed it — respond

    cat-sis2go-utils 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.

  3. Did it already run?

    If cat-sis2go-utils 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. cat-sis2go-utils on npm has been identified as a malicious package (versions 99.0.0, 99.1.0 flagged). It should be removed immediately — do not install or keep it in your dependency tree.

Campaign

IN-MAL-2026-019843IN-MAL-2026-019845

References

Credits

  • Amazon Inspector · finder
  • smilinghyena4 · finder
  • pkgwarden · finder

Detect & block this

O3 blocks cat-sis2go-utils-class packages before install and in CI — and if it already ran, its runtime egress monitoring catches the credential exfiltration and severs the channel.

Explore

cat-sis2go-utils (npm) malicious package — MAL-2026-16071 | O3 Security