boxy-client-loadernpm
Advisory published Updated
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
Search your lockfiles and build artifacts for boxy-client-loader (version 35.8.6).
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 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
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.