MAL-2026-12747 Malicious code in devplatform-s3-client (npm)

On require of the package's main entry, bridge.js assembles Cloudflare Workers hostnames from string fragments via Array.join (e.g. 'oob-worker.cf102-baf.workers.dev', 'cf101-adf.workers.dev', 'cf99-9b3.workers.dev'), downloads a platform-specific binary via https.get, writes it to /var/tmp or %TEMP% under a decoy name (.cache<rnd> on Unix, dotnet_diag_<rnd>.exe on Windows), sets it executable with chmod 0755, and spawns it detached via /bin/sh -c or cmd.exe /c start /b. If HTTPS fetches fail, _bridge.js falls back to a DNS-TXT covert channel: it resolves TXT records at c.<domain> and numbered subdomains under an obfuscated 'sdk.dl.wel1.ru' family to reassemble a base64-encoded binary, then writes and executes it. A persistence-stamp file gates re-execution across imports. The hostnames are split into fragments to evade static grep, decoy filenames masquerade as OS diagnostic caches, and none of this behavior is part of an S3 client.

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.