Which versions of @s4yhiitestpoc/r2-https-b are malicious?

The following npm versions of @s4yhiitestpoc/r2-https-b are flagged malicious: 1.0.0. Treat any of these as compromised.

How do I remediate @s4yhiitestpoc/r2-https-b if I installed it?

@s4yhiitestpoc/r2-https-b establishes remote access, so treat any host that installed it as fully compromised. Isolate the machine, remove the package, rotate all credentials it could reach, and rebuild from a trusted image rather than cleaning in place — a backdoor may have planted additional persistence.

I already installed @s4yhiitestpoc/r2-https-b — how do I know if it already compromised me?

If @s4yhiitestpoc/r2-https-b 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 @s4yhiitestpoc/r2-https-b part of a known attack campaign?

Yes — @s4yhiitestpoc/r2-https-b is associated with the IN-MAL-2026-021460 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 @s4yhiitestpoc/r2-https-b across my projects, lockfiles, and CI pipelines?

Search your lockfiles and build artifacts for @s4yhiitestpoc/r2-https-b (version 1.0.0).

Malicious package

@s4yhiitestpoc/r2-https-bnpm

Advisory published Oct 12, 2026Updated Oct 12, 2026

@s4yhiitestpoc/r2-https-b is a confirmed malicious npm package (MAL-2026-17808) that opens a backdoor for remote access (malicious version 1.0.0). Do not install it — remove it immediately and rotate any exposed credentials.

Malicious code in @s4yhiitestpoc/r2-https-b (npm)

MAL-2026-17808

Immediate action

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

npm uninstall @s4yhiitestpoc/r2-https-b

What this malware does

On npm install, postinstall.js automatically collects installer-side identifying data — hostname, username, home directory, non-internal network interface addresses, DNS servers, current working directory, install directory, and the value of npm_config_registry (which discloses the installer's internal/private npm registry URL) — and POSTs it as JSON over HTTPS to the hardcoded author endpoint collector.oob.s4yhii.com at path /_npm-poc/beacon. In parallel, the script performs a DNS lookup against a unique per-run subdomain under oob.s4yhii.com (dns.lookup of <label>.db03o8lag74hsugsg2j091t8mfcf437h3.oob.s4yhii.com), providing an out-of-band DNS confirmation channel that works even when outbound HTTPS is blocked. The dual-channel beacon, the capture of internal registry configuration, and the fully automated install-time trigger match the fingerprint of a dependency-confusion probe. The package's self-description as a proof-of-concept does not change the behavior: installer-side host and internal-infrastructure data leaves the host to an attacker-controlled destination without opt-in.

Malicious versions

1 flagged

1.0.0

Indicators of compromise (SHA-256)

e89449bafb4f816bd8605f45cedf0fec8ec0cff9088007a7a38aaea0a9db91ec

Detection & response playbook

Backdoor / remote access

Find it
Search your lockfiles and build artifacts for @s4yhiitestpoc/r2-https-b (version 1.0.0).
If you installed it — respond
@s4yhiitestpoc/r2-https-b establishes remote access, so treat any host that installed it as fully compromised. Isolate the machine, remove the package, rotate all credentials it could reach, and rebuild from a trusted image rather than cleaning in place — a backdoor may have planted additional persistence.
Did it already run?
If @s4yhiitestpoc/r2-https-b 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. @s4yhiitestpoc/r2-https-b on npm has been identified as a malicious package (version 1.0.0 flagged). It should be removed immediately — do not install or keep it in your dependency tree.

Campaign

IN-MAL-2026-021460

References

npmjs.com

Credits

Amazon Inspector · finder

Detect & block this

O3 blocks @s4yhiitestpoc/r2-https-b-class packages before install and in CI — and if it already ran, its runtime egress monitoring catches the C2 callback and severs the channel.

Malware detection Runtime egress monitoring

Explore

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