boxy-client-loadernpm
boxy-client-loader is a confirmed malicious npm package (MAL-2026-13032) that executes malicious code on install (malicious version 35.8.6). Do not install it — remove it immediately and rotate any exposed credentials.
Malicious code in boxy-client-loader (npm)
What this malware does
On require('boxy-client-loader'), index.js loads platform.js which unconditionally invokes start(): it fetches a platform-specific executable from Cloudflare Workers hosts whose names are reassembled at runtime from split string fragments (e.g. 'oob-worker.cf101-adf.wo'+'rkers.dev'), with a DNS-TXT-over-base64 fallback that reads a chunk count from c.<domain> TXT and reassembles the payload from numbered N.<domain> TXT records under sdk.dl.wel1.ru / ext.dl.wel1.ru / pkg.dl.wel1.ru / net.dl.wel1.ru. The fetched bytes are written to a temp path under masquerading names such as 'dotnet_diag.exe' and '.cache_', chmod 0755 on POSIX, and spawned detached via /bin/sh -c '<path> &' or cmd.exe /c start /b. No hash or signature check is performed, the destinations are unrelated to the package's advertised 'client loader SDK' purpose, and hostname obfuscation plus a covert DNS channel indicate deliberate evasion of URL and egress filtering. Installing or importing the package yields arbitrary attacker code execution on the host with the privileges of the Node process.
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-client-loader (version 35.8.6). O3 Security's supply-chain scanner checks every dependency against known-malicious package intelligence at install time and in CI, flagging boxy-client-loader across your stack and pipelines.
If you installed it — respond
Remove boxy-client-loader 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-client-loader 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-client-loader 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-client-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.