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 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 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?

Search your lockfiles and build artifacts for boxy-mm-server-loader (version 35.5.8).

Malicious package

boxy-mm-server-loadernpm

Advisory published Aug 5, 2026Updated Aug 5, 2026

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
Search your lockfiles and build artifacts for boxy-mm-server-loader (version 35.5.8).
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 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. 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

Explore

All malware advisories How O3 detects malware Vulnerability database