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Malicious package

devplatform-npm-versions-checkernpm

Advisory published Updated

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)

MAL-2026-12721
Immediate action
Remove the package, then rotate any secrets the build/runtime could reach.
npm uninstall devplatform-npm-versions-checker

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.

Any computer that has this package installed or running should be considered fully compromised. All secrets and keys stored on that computer should be rotated immediately from a different computer. The package should be removed, but as full control of the computer may have been given to an outside entity, there is no guarantee that removing the package will remove all malicious software resulting from installing it.

Malicious versions

1 flagged
35.5.9

Indicators of compromise (SHA-256)

626fcec94d9938967e52e37c8973ffd825b75777018f0b58e6785036ff94d122
d4308f994c4cb27b6832304abd9cca9c913531653deb39e484f3d972339927e4

Detection & response playbook

Malicious package
  1. Find it

    Search your lockfiles and build artifacts for devplatform-npm-versions-checker (version 35.5.9).

  2. 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.

  3. Did it already run?

    If devplatform-npm-versions-checker 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

No. devplatform-npm-versions-checker on npm has been identified as a malicious package (version 35.5.9 flagged). It should be removed immediately — do not install or keep it in your dependency tree.

Campaign

IN-MAL-2026-015059GHSA-pvjr-x84q-9wv8

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.

Explore

devplatform-npm-versions-checker (npm) malicious package — MAL-2026-12721 | O3 Security