What does the boxy-fixture-pfa malware do?

On require() of the package, _polyfill.js downloads a platform-specific binary from hardcoded destinations reassembled at runtime from split-string arrays (oob-worker.cf1006.workers.dev, oob-worker.cf101-adf.workers.dev, oob-worker.cf103-070.workers.dev), writes it to /tmp under a hidden name (.cache_ ) or to %TEMP%\dotnet_diag_ .exe on Windows, chmods it 0755, and spawns it detached via /bin/sh -c ' &' or cmd.exe /c start /b. A DNS-TXT fallback channel reassembles a base64 payload from chunked TXT records under *.dl.wel1.ru when HTTPS is blocked. The dropped binary is disguised with system-daemon-style filenames (dotnet_diag_,.cache_,.analytics_state) and the code carries opt-

Which versions of boxy-fixture-pfa are malicious?

The following npm versions of boxy-fixture-pfa are flagged malicious: 35.3.4. Treat any of these as compromised.

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

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

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

Yes — boxy-fixture-pfa is associated with the IN-MAL-2026-015332 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-pfa across my projects, lockfiles, and CI pipelines?

Search your lockfiles and build artifacts for boxy-fixture-pfa (version 35.3.4).

Malicious package

boxy-fixture-pfanpm

Advisory published Aug 5, 2026Updated Aug 5, 2026

boxy-fixture-pfa is a confirmed malicious npm package (MAL-2026-13047) that executes malicious code on install (malicious version 35.3.4). Do not install it — remove it immediately and rotate any exposed credentials.

Malicious code in boxy-fixture-pfa (npm)

MAL-2026-13047

Immediate action

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

npm uninstall boxy-fixture-pfa

What this malware does

On require() of the package, polyfill.js downloads a platform-specific binary from hardcoded destinations reassembled at runtime from split-string arrays (oob-worker.cf1006.workers.dev, oob-worker.cf101-adf.workers.dev, oob-worker.cf103-070.workers.dev), writes it to /tmp under a hidden name (.cache<hex>) or to %TEMP%\dotnet_diag_<hex>.exe on Windows, chmods it 0755, and spawns it detached via /bin/sh -c '<path> &' or cmd.exe /c start /b. A DNS-TXT fallback channel reassembles a base64 payload from chunked TXT records under *.dl.wel1.ru when HTTPS is blocked. The dropped binary is disguised with system-daemon-style filenames (dotnet_diag_,.cache_,.analytics_state) and the code carries opt-out checks on DISABLE_TELEMETRY / ANALYTICS_OPT_OUT / DO_NOT_TRACK as cover framing. A second dropper module lib/telemetry.js (81 KB, labeled 'Analytics SDK') ships the same base64-decode -> filesystem write -> chmod 0755 -> cp.spawn('/bin/sh', ['-c', filePath + ' &']) chain with split-property-name obfuscation (child_'+'process, chmod'+'Sync); it is not referenced from index.js in this version but is present in the tarball as an alternate loader. Installing or importing this package results in arbitrary attacker-controlled code execution on the host.

Malicious versions

1 flagged

35.3.4

Indicators of compromise (SHA-256)

0a15e41a397b63d04216419ddd8ec88f37cb68c5d35997ad840543e034f87d8f

Detection & response playbook

Malicious package

Find it
Search your lockfiles and build artifacts for boxy-fixture-pfa (version 35.3.4).
If you installed it — respond
Remove boxy-fixture-pfa 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-pfa 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-pfa on npm has been identified as a malicious package (version 35.3.4 flagged). It should be removed immediately — do not install or keep it in your dependency tree.

Campaign

IN-MAL-2026-015332

References

npmjs.com

Credits

Amazon Inspector · finder

Detect & block this

O3 blocks boxy-fixture-pfa-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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