Which versions of contoso-login-sim-loader are malicious?

The following npm versions of contoso-login-sim-loader are flagged malicious: 1.0.1. Treat any of these as compromised.

How do I remediate contoso-login-sim-loader if I installed it?

contoso-login-sim-loader 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 contoso-login-sim-loader — how do I know if it already compromised me?

If contoso-login-sim-loader 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 contoso-login-sim-loader part of a known attack campaign?

Yes — contoso-login-sim-loader is associated with the IN-MAL-2026-020808 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 contoso-login-sim-loader 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 contoso-login-sim-loader (version 1.0.1). O3 Security's supply-chain scanner checks every dependency against known-malicious package intelligence at install time and in CI, flagging contoso-login-sim-loader across your stack and pipelines.

Malicious package

contoso-login-sim-loadernpm

contoso-login-sim-loader is a confirmed malicious npm package (MAL-2026-17322) that steals credentials and exfiltrates sensitive data (malicious version 1.0.1). Do not install it — remove it immediately and rotate any exposed credentials.

Malicious code in contoso-login-sim-loader (npm)

MAL-2026-17322

Immediate action

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

npm uninstall contoso-login-sim-loader

What this malware does

Package ships a single ~138 KB browser script whose entire body is an RC4-encrypted base64 blob decoded at runtime by an inline RC4 routine (_zc) with a DJB2 helper (_zh) and a key reconstructed by XORing a numeric array with 1410^714. Before decryption the script performs anti-analysis guards: a devtools-size heuristic (if(_gz>160||_gp>160)return;) that aborts execution when developer tools are open, and a block that overwrites console.log/info/warn/debug/error to no-ops to suppress runtime tracing. The package name contoso-login-sim-loader self-describes as a 'login sim(ulator) loader' while the published description reframes it as a generic 'Client-side asset loader that renders a self-contained UI component when included via a script tag.' The tarball ships no source, no exports, no dependencies, and no documentation - only the opaque encrypted payload. Any site that follows the include-via-script-tag guidance embeds attacker-controlled JavaScript, decrypted only in end-user browsers, into its own pages; the concealed payload cannot be audited without executing it, and the name plus cover-story description are consistent with a fake-login/credential-harvest overlay served to that site's visitors.

Malicious versions

1 flagged

1.0.1

Indicators of compromise (SHA-256)

062ce76699c91a883d24e3ad609bb04faa3f52cbeaecfb24c1c3bcde8b496a5c

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 contoso-login-sim-loader (version 1.0.1). O3 Security's supply-chain scanner checks every dependency against known-malicious package intelligence at install time and in CI, flagging contoso-login-sim-loader across your stack and pipelines.
If you installed it — respond
contoso-login-sim-loader 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 contoso-login-sim-loader 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 contoso-login-sim-loader 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. contoso-login-sim-loader on npm has been identified as a malicious package (version 1.0.1 flagged). It should be removed immediately — do not install or keep it in your dependency tree.

Campaign

IN-MAL-2026-020808

References

npmjs.com

Credits

Amazon Inspector · finder

Detect & block this

O3 blocks contoso-login-sim-loader-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

All malware advisories How O3 detects malware Vulnerability database