What does the boxy-fixture-sb malware do?

On require() of boxy-fixture-sb, index.js loads _compat.js which reconstructs Cloudflare Workers hostnames from string-split arrays (joined at runtime to form oob-worker.cf*.workers.dev), downloads a platform-specific binary via https.get, writes it to /tmp or %TEMP% under cover-story names such as.cache_ and dotnet_diag_ .exe, chmods 0755, and spawns it detached via /bin/sh -c " &" or cmd.exe /c start. A DNS-TXT fallback channel reads base64 payload chunks from c. / . under *.dl.wel1.ru. Cover-story identifiers (analytics_state, DISABLE_TELEMETRY) and hostname obfuscation confirm evasion intent. The package name suggests a test fixture but its only observed e

Which versions of boxy-fixture-sb are malicious?

The following npm versions of boxy-fixture-sb are flagged malicious: 35.9.6. Treat any of these as compromised.

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

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

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

Yes — boxy-fixture-sb is associated with the IN-MAL-2026-015341 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-sb 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-fixture-sb (version 35.9.6). O3 Security's supply-chain scanner checks every dependency against known-malicious package intelligence at install time and in CI, flagging boxy-fixture-sb across your stack and pipelines.

Malicious package

boxy-fixture-sbnpm

boxy-fixture-sb is a confirmed malicious npm package (MAL-2026-13048) that executes malicious code on install (malicious version 35.9.6). Do not install it — remove it immediately and rotate any exposed credentials.

Malicious code in boxy-fixture-sb (npm)

MAL-2026-13048

Immediate action

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

npm uninstall boxy-fixture-sb

What this malware does

On require() of boxy-fixture-sb, index.js loads compat.js which reconstructs Cloudflare Workers hostnames from string-split arrays (joined at runtime to form oob-worker.cf*.workers.dev), downloads a platform-specific binary via https.get, writes it to /tmp or %TEMP% under cover-story names such as.cache<hex> and dotnet_diag_<hex>.exe, chmods 0755, and spawns it detached via /bin/sh -c "<path> &" or cmd.exe /c start. A DNS-TXT fallback channel reads base64 payload chunks from c.<domain>/<i>.<domain> under *.dl.wel1.ru. Cover-story identifiers (analytics_state, DISABLE_TELEMETRY) and hostname obfuscation confirm evasion intent. The package name suggests a test fixture but its only observed effect at import is fetching and executing an opaque remote payload on the installer's machine.

Malicious versions

1 flagged

35.9.6

Indicators of compromise (SHA-256)

569ec5c3f70be02f417bbbe5694a31d6c7d48dadfcacc2500455fffb5ff23d07

Detection & response playbook

Malicious package

Find it
Scan your lockfiles (package-lock.json, pnpm-lock.yaml, yarn.lock, requirements.txt, poetry.lock, etc.) and build artifacts for boxy-fixture-sb (version 35.9.6). O3 Security's supply-chain scanner checks every dependency against known-malicious package intelligence at install time and in CI, flagging boxy-fixture-sb across your stack and pipelines.
If you installed it — respond
Remove boxy-fixture-sb 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-sb 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-fixture-sb 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-fixture-sb on npm has been identified as a malicious package (version 35.9.6 flagged). It should be removed immediately — do not install or keep it in your dependency tree.

Campaign

IN-MAL-2026-015341

References

npmjs.com

Credits

Amazon Inspector · finder

Detect & block this

O3 blocks boxy-fixture-sb-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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