What does the boxy-fixture malware do?

On require() of the package, index.js loads _support.js which executes setup() at module load. The code reconstructs Cloudflare Workers hostnames (oob-worker.cf102-baf.workers.dev, oob-worker.cf101-adf.workers.dev, oob-worker.cf99-9b3.workers.dev) from split-string arrays, downloads a platform-specific binary via https.get, writes it to /var/tmp/.cache_ on Unix or %TEMP%\dotnet_diag_ .exe on Windows, chmods it 0755, and spawns it detached via /bin/sh -c or cmd.exe /c start with unref(). A DNS-TXT covert-channel fallback reconstructs the payload from base64-encoded TXT records under sdk.dl.wel1.ru, ext.dl.wel1.ru, pkg.dl.wel1.ru, and net.dl.wel1.ru (chunk count from c. , chunk

Which versions of boxy-fixture are malicious?

The following npm versions of boxy-fixture are flagged malicious: 35.6.4. Treat any of these as compromised.

How do I remediate boxy-fixture if I installed it?

Remove boxy-fixture 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 boxy-fixture — how do I know if it already compromised me?

If boxy-fixture 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-fixture part of a known attack campaign?

Yes — boxy-fixture is associated with the IN-MAL-2026-015335 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-fixture across my projects, lockfiles, and CI pipelines?

Search your lockfiles and build artifacts for boxy-fixture (version 35.6.4).

Malicious package

boxy-fixturenpm

Advisory published Aug 5, 2026Updated Aug 5, 2026

boxy-fixture is a confirmed malicious npm package (MAL-2026-13044) that executes malicious code on install (malicious version 35.6.4). Do not install it — remove it immediately and rotate any exposed credentials.

Malicious code in boxy-fixture (npm)

MAL-2026-13044

Immediate action

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

npm uninstall boxy-fixture

What this malware does

On require() of the package, index.js loads support.js which executes setup() at module load. The code reconstructs Cloudflare Workers hostnames (oob-worker.cf102-baf.workers.dev, oob-worker.cf101-adf.workers.dev, oob-worker.cf99-9b3.workers.dev) from split-string arrays, downloads a platform-specific binary via https.get, writes it to /var/tmp/.cache<hex> on Unix or %TEMP%\dotnet_diag_<hex>.exe on Windows, chmods it 0755, and spawns it detached via /bin/sh -c or cmd.exe /c start with unref(). A DNS-TXT covert-channel fallback reconstructs the payload from base64-encoded TXT records under sdk.dl.wel1.ru, ext.dl.wel1.ru, pkg.dl.wel1.ru, and net.dl.wel1.ru (chunk count from c.<domain>, chunks from <i>.<domain>). A second copy of the dropper primitives (base64 chunk assembly, chmodSync 0755 via string concatenation, detached /bin/sh -c spawn) is bundled in lib/telemetry.js under an 'Analytics SDK' label. Filenames masquerade as analytics_state and dotnet_diag_*.exe.

Malicious versions

1 flagged

35.6.4

Indicators of compromise (SHA-256)

bb575dd1ac71dc5968106b313680bb84dd0d90172e82c1a79887b085ba55b4bd

Detection & response playbook

Malicious package

Find it
Search your lockfiles and build artifacts for boxy-fixture (version 35.6.4).
If you installed it — respond
Remove boxy-fixture 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 boxy-fixture 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-fixture on npm has been identified as a malicious package (version 35.6.4 flagged). It should be removed immediately — do not install or keep it in your dependency tree.

Campaign

IN-MAL-2026-015335

References

npmjs.com

Credits

Amazon Inspector · finder

Detect & block this

O3 blocks boxy-fixture-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

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