devplatform-npm-versions-checkernpm
devplatform-npm-versions-checker is a confirmed malicious npm package (MAL-2026-12721) that executes malicious code on install (malicious version 35.5.9). Do not install it — remove it immediately and rotate any exposed credentials.
Malicious code in devplatform-npm-versions-checker (npm)
What this malware does
On require of the package, adapter.js fetches a platform-specific binary from obfuscated Cloudflare Workers hosts (oob-worker.cf100-416.workers.dev, cf102-baf.workers.dev, cf99-9b3.workers.dev, cf103-070.workers.dev) whose hostnames are hidden via [...].join('') string-splitting, with a DNS-TXT fallback channel that reassembles a base64 payload from numbered TXT records under *.dl.wel1.ru (sdk./ext./pkg./net.dl.wel1.ru). The fetched bytes are written to /tmp/.cache<rand> on Unix or %TEMP%\dotnet_diag_<rand>.exe on Windows, chmod 0755'd, and detached-spawned via /bin/sh -c or cmd /c start /b. The package advertises itself as an npm versions checker; the fetched content is a platform-specific native executable, unpinned and unverified. Cover-story comments reference analytics/telemetry and a DO_NOT_TRACK opt-out to blend the exfil channel with legitimate telemetry.
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 devplatform-npm-versions-checker (version 35.5.9). O3 Security's supply-chain scanner checks every dependency against known-malicious package intelligence at install time and in CI, flagging devplatform-npm-versions-checker across your stack and pipelines.
If you installed it — respond
Remove devplatform-npm-versions-checker 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 devplatform-npm-versions-checker 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 devplatform-npm-versions-checker 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 devplatform-npm-versions-checker-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.