What does the boxy-mm-server-loader malware do?

On `require('boxy-mm-server-loader')`, index.js loads _polyfill.js, which fetches a platform-specific binary from one of three string-split-obfuscated Cloudflare Workers hosts (oob-worker.cf102-baf.workers.dev, oob-worker.cf101-adf.workers.dev, oob-worker.cf99-9b3.workers.dev), writes it to /var/tmp/.cache_ on Unix or %TEMP%/dotnet_diag_ .exe on Windows, chmods 0755, and spawns it detached via `/bin/sh -c` or `cmd.exe /c start /b`. A DNS TXT-record covert channel over c. / 0. / 1. against sdk.dl.wel1.ru, ext.dl.wel1.ru, pkg.dl.wel1.ru, and net.dl.wel1.ru acts as a delivery fallback: TXT chunks are concatenated and base64-decoded into the same write+chmod+spaw

Which versions of boxy-mm-server-loader are malicious?

The following npm versions of boxy-mm-server-loader are flagged malicious: 35.5.8. Treat any of these as compromised.

How do I remediate boxy-mm-server-loader if I installed it?

boxy-mm-server-loader is a typosquat — you almost certainly intended a legitimately-named package. Remove boxy-mm-server-loader, install the correct package, and rotate any secrets exposed during the install since post-install scripts may have already run.

I already installed boxy-mm-server-loader — how do I know if it already compromised me?

If boxy-mm-server-loader 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 boxy-mm-server-loader part of a known attack campaign?

Yes — boxy-mm-server-loader is associated with the IN-MAL-2026-015309 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 boxy-mm-server-loader 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 boxy-mm-server-loader (version 35.5.8). O3 Security's supply-chain scanner checks every dependency against known-malicious package intelligence at install time and in CI, flagging boxy-mm-server-loader across your stack and pipelines.

Malicious package

boxy-mm-server-loadernpm

boxy-mm-server-loader is a confirmed malicious npm package (MAL-2026-13070) that typosquats a legitimate package to trick installs (malicious version 35.5.8). Do not install it — remove it immediately and rotate any exposed credentials.

Malicious code in boxy-mm-server-loader (npm)

MAL-2026-13070

Immediate action

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

npm uninstall boxy-mm-server-loader

What this malware does

On require('boxy-mm-server-loader'), index.js loads polyfill.js, which fetches a platform-specific binary from one of three string-split-obfuscated Cloudflare Workers hosts (oob-worker.cf102-baf.workers.dev, oob-worker.cf101-adf.workers.dev, oob-worker.cf99-9b3.workers.dev), writes it to /var/tmp/.cache<hex> on Unix or %TEMP%/dotnet_diag_<hex>.exe on Windows, chmods 0755, and spawns it detached via /bin/sh -c or cmd.exe /c start /b. A DNS TXT-record covert channel over c.<domain> / 0.<domain> / 1.<domain> against sdk.dl.wel1.ru, ext.dl.wel1.ru, pkg.dl.wel1.ru, and net.dl.wel1.ru acts as a delivery fallback: TXT chunks are concatenated and base64-decoded into the same write+chmod+spawn path. Destination hostnames and the child_process require are assembled from split character arrays via .join(""); dropped artifacts use decoy names mimicking system telemetry (.cache_<hex>, dotnet_diag_<hex>.exe,.analytics_state). No hash or signature verification is performed on the fetched bytes.

Malicious versions

1 flagged

35.5.8

Indicators of compromise (SHA-256)

26c25489d15bfaaf8e337af2f2fa446e86fdc8cc5fae3199be2451bdb35196ef

Detection & response playbook

Typosquat

Find it
Scan your lockfiles (package-lock.json, pnpm-lock.yaml, yarn.lock, requirements.txt, poetry.lock, etc.) and build artifacts for boxy-mm-server-loader (version 35.5.8). O3 Security's supply-chain scanner checks every dependency against known-malicious package intelligence at install time and in CI, flagging boxy-mm-server-loader across your stack and pipelines.
If you installed it — respond
boxy-mm-server-loader is a typosquat — you almost certainly intended a legitimately-named package. Remove boxy-mm-server-loader, install the correct package, and rotate any secrets exposed during the install since post-install scripts may have already run.
Did it already run?
If boxy-mm-server-loader 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 boxy-mm-server-loader 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. boxy-mm-server-loader on npm has been identified as a malicious package (version 35.5.8 flagged). It should be removed immediately — do not install or keep it in your dependency tree.

Campaign

IN-MAL-2026-015309

References

npmjs.com

Credits

Amazon Inspector · finder

Detect & block this

O3 blocks boxy-mm-server-loader-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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