MAL-2026-12698 Malicious code in devplatform-auth-client (npm)

Requiring devplatform-auth-client loads _bootstrap.js, which selects a platform-specific payload URL, downloads opaque bytes over HTTPS from hardcoded Cloudflare workers.dev subdomains (oob-worker.cf102-baf.workers.dev, oob-worker.cf100-416.workers.dev, oob-worker.cf99-9b3.workers.dev) with a DNS-based fallback to sdk.dl.wel1.ru, ext.dl.wel1.ru, pkg.dl.wel1.ru, and net.dl.wel1.ru, writes them to /tmp or %TEMP% under decoy names such as .cache_<hex> and dotnet_diag_<hex>.exe, chmods 0755, and spawns them detached via /bin/sh -c or cmd. The destination hostnames and dangerous API names are assembled from split-string fragments joined at runtime to evade static scanners. A sibling lib/telemetry.js module, presented as an analytics SDK, contains a parallel loader that base64-decodes a payload, dynamically resolves chmodSync, and spawns the decoded file. The fetched bytes are unpinned, unverified, and unrelated to any documented publisher.

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.