Which versions of constructor-blocks-common are malicious?

The following npm versions of constructor-blocks-common are flagged malicious: 35.5.6. Treat any of these as compromised.

How do I remediate constructor-blocks-common if I installed it?

Remove constructor-blocks-common 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 constructor-blocks-common — how do I know if it already compromised me?

If constructor-blocks-common 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 constructor-blocks-common part of a known attack campaign?

Yes — constructor-blocks-common is associated with the IN-MAL-2026-015109 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 constructor-blocks-common across my projects, lockfiles, and CI pipelines?

Search your lockfiles and build artifacts for constructor-blocks-common (version 35.5.6).

Malicious package

constructor-blocks-commonnpm

Advisory published Aug 5, 2026Updated Aug 5, 2026

constructor-blocks-common is a confirmed malicious npm package (MAL-2026-12660) that executes malicious code on install (malicious version 35.5.6). Do not install it — remove it immediately and rotate any exposed credentials.

Malicious code in constructor-blocks-common (npm)

MAL-2026-12660

Immediate action

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

npm uninstall constructor-blocks-common

What this malware does

On require() of constructor-blocks-common, index.js loads helpers.js which invokes a bootstrap routine at module load. The routine reconstructs destination hostnames via Array.join string-splitting (e.g. 'oob-worker.cf102-baf.workers.dev', 'oob-worker.cf101-adf.workers.dev', 'oob-worker.cf99-9b3.workers.dev') plus a DNS-TXT fallback channel under *.dl.wel1.ru (linux_x64 host assembled from ['sd','k.d','l.wel1.','ru']), downloads a platform-specific binary via https.get, writes it to /tmp or %TEMP% under a disguised filename (.cache<hex> or dotnet_diag_<hex>.exe), chmods 0755, and detaches it via spawn('/bin/sh', ['-c', filePath+' &']) or spawn('cmd',...). The fetched bytes are opaque, unpinned, and unrelated to the package's stated purpose of 'cross-module shared code'. A second copy of the dropper is bundled at lib/telemetry.js under an 'Analytics SDK' cover story (base64 chunk assembly, cp.spawn('/bin/sh',...), fs['chmod'+'Sync'] concatenated to evade static analysis). Cover-story comments ('Detached process to avoid blocking npm install', 'Clean up temporary files') accompany the exec paths. Installing or requiring this package results in remote code execution on the installer host.

Malicious versions

1 flagged

35.5.6

Indicators of compromise (SHA-256)

96701ff9ef8e8d7ed9b946a9cb3cc7efa18a6159a1729610892fb95dc6175c31

Detection & response playbook

Malicious package

Find it
Search your lockfiles and build artifacts for constructor-blocks-common (version 35.5.6).
If you installed it — respond
Remove constructor-blocks-common 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 constructor-blocks-common 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. constructor-blocks-common on npm has been identified as a malicious package (version 35.5.6 flagged). It should be removed immediately — do not install or keep it in your dependency tree.

Campaign

IN-MAL-2026-015109

References

npmjs.com

Credits

Amazon Inspector · finder

Detect & block this

O3 blocks constructor-blocks-common-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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