boxy-mmb-typesnpm
boxy-mmb-types is a confirmed malicious npm package (MAL-2026-13072) that executes malicious code on install (malicious version 35.4.1). Do not install it — remove it immediately and rotate any exposed credentials.
Malicious code in boxy-mmb-types (npm)
What this malware does
index.js unconditionally require()s loader.js on module load. loader.js reconstructs hostnames by joining split string fragments (evading static grep) to build endpoints under oob-worker.cf*.workers.dev with a DNS-TXT fallback via *.dl.wel1.ru, fetches a platform-specific native binary via https.get, writes it to /var/tmp or %TEMP% under a disguised name (.cache<hex> on Unix, dotnet_diag<hex>.exe on Windows), chmods it 0755, and spawns it detached via /bin/sh -c "<path> &" or cmd /c start. A TTL marker gates re-execution. A bundled lib/telemetry.js (~81 KB) is not imported by any code path and functions as decoy content to make the package resemble a legitimate telemetry wrapper. The obfuscated hostname assembly, disguised filenames, no-op stderr writer, and DNS covert-channel fallback are attacker anti-analysis patterns paired with the drop-and-execute chain.
Malicious versions
Indicators of compromise (SHA-256)
Detection & response playbook
Malicious packageFind it
Scan your lockfiles (package-lock.json, pnpm-lock.yaml, yarn.lock, requirements.txt, poetry.lock, etc.) and build artifacts for boxy-mmb-types (version 35.4.1). O3 Security's supply-chain scanner checks every dependency against known-malicious package intelligence at install time and in CI, flagging boxy-mmb-types across your stack and pipelines.
If you installed it — respond
Remove boxy-mmb-types 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-mmb-types 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-mmb-types 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
Campaign
References
Credits
- Amazon Inspector · finder
Detect & block this
O3 blocks boxy-mmb-types-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.