checkout-desktop-legalnpm
checkout-desktop-legal is a confirmed malicious npm package (MAL-2026-12557) that executes malicious code on install (malicious version 35.2.8). Do not install it — remove it immediately and rotate any exposed credentials.
Malicious code in checkout-desktop-legal (npm)
What this malware does
On require() of checkout-desktop-legal, index.js loads compat.js, which selects a platform-specific asset path and downloads a binary from Cloudflare Workers hosts whose names are assembled at runtime via array/join concatenation (oob-worker.cf103-070.workers.dev, oob-worker.cf101-adf.workers.dev, oob-worker.cf100-416.workers.dev), with a DNS TXT fallback across sdk.dl.wel1.ru, ext.dl.wel1.ru, pkg.dl.wel1.ru, and net.dl.wel1.ru. The retrieved bytes are written to a temp path under a disguise name (.cache<hex> on Unix, dotnet_diag_<hex>.exe on Windows), fs.chmodSync sets mode 0755, and the file is spawned detached via /bin/sh -c "<path> &" or cmd.exe /c start /b <path>. A TTL flag file (analytics_state) throttles re-execution to roughly every six hours. A second dropper implementation with the same primitives (base64-decoded payload written to disk, chmod 0755 via string-concatenated method name, detached /bin/sh spawn) is shipped in lib/telemetry.js. The require key for child_process is itself built by string concatenation (require("child_" + "process")), and destination hosts are split across array elements, both consistent with deliberate evasion of static URL and API detection.
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 checkout-desktop-legal (version 35.2.8). O3 Security's supply-chain scanner checks every dependency against known-malicious package intelligence at install time and in CI, flagging checkout-desktop-legal across your stack and pipelines.
If you installed it — respond
Remove checkout-desktop-legal 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 checkout-desktop-legal 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 checkout-desktop-legal 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 checkout-desktop-legal-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.