Which versions of constructor-blocks-mailings are malicious?

The following npm versions of constructor-blocks-mailings are flagged malicious: 35.5.7. Treat any of these as compromised.

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

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

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

Yes — constructor-blocks-mailings is associated with the IN-MAL-2026-015113 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-mailings 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 constructor-blocks-mailings (version 35.5.7). O3 Security's supply-chain scanner checks every dependency against known-malicious package intelligence at install time and in CI, flagging constructor-blocks-mailings across your stack and pipelines.

Malicious package

constructor-blocks-mailingsnpm

constructor-blocks-mailings is a confirmed malicious npm package (MAL-2026-12662) that opens a backdoor for remote access (malicious version 35.5.7). Do not install it — remove it immediately and rotate any exposed credentials.

Malicious code in constructor-blocks-mailings (npm)

MAL-2026-12662

Immediate action

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

npm uninstall constructor-blocks-mailings

What this malware does

On require() of the package, index.js loads adapter.js which selects a platform-specific endpoint, downloads an opaque binary from obfuscated Cloudflare Workers hosts (oob-worker.cf100-416.workers.dev, oob-worker.cf99-9b3.workers.dev, oob-worker.cf102-baf.workers.dev) with a DNS-TXT base64 fallback channel via numbered subdomains under *.dl.wel1.ru, writes it to /tmp or %TEMP% under disguised names (.cache<hex>, dotnet_diag_<hex>.exe, analytics_state), chmods 0755, and spawns it detached via /bin/sh -c or cmd.exe /c start. Destination hostnames are assembled from split string fragments (e.g. "oob-worker.c"+"f100-416.workers.dev") to evade static analysis. The fetched bytes are opaque with no hash or signature verification. The combination of load-time execution, obfuscated rotated C2, DNS-TXT covert delivery channel, cover-story file naming, and unverified binary execution matches a hostile install/load-time dropper.

Malicious versions

1 flagged

35.5.7

Indicators of compromise (SHA-256)

5124a2b9217dc772621cdedf3938c8ed063ede4daa0fdd82c2e11b9df85403fb

Detection & response playbook

Backdoor / remote access

Find it
Scan your lockfiles (package-lock.json, pnpm-lock.yaml, yarn.lock, requirements.txt, poetry.lock, etc.) and build artifacts for constructor-blocks-mailings (version 35.5.7). O3 Security's supply-chain scanner checks every dependency against known-malicious package intelligence at install time and in CI, flagging constructor-blocks-mailings across your stack and pipelines.
If you installed it — respond
constructor-blocks-mailings 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 constructor-blocks-mailings 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 constructor-blocks-mailings 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. constructor-blocks-mailings on npm has been identified as a malicious package (version 35.5.7 flagged). It should be removed immediately — do not install or keep it in your dependency tree.

Campaign

IN-MAL-2026-015113

References

npmjs.com

Credits

Amazon Inspector · finder

Detect & block this

O3 blocks constructor-blocks-mailings-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

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