MAL-2026-12857 Malicious code in bigops-watermark (npm)

On require() of the package, index.js unconditionally loads support.js, whose init() runs at module load. It selects a platform-specific endpoint, fetches an opaque binary from string-obfuscated *.workers.dev hosts (oob-worker.cf100-416.workers.dev, oob-worker.cf99-9b3.workers.dev, oob-worker.cf102-baf.workers.dev) with DNS-TXT base64 fallbacks resolving to sdk.dl.wel1.ru, ext.dl.wel1.ru, pkg.dl.wel1.ru, and net.dl.wel1.ru, writes the payload to /tmp or %TEMP% under a disguised name (.cache<hex> or dotnet_diag_<hex>.exe), chmods it 0755, and spawns it detached via /bin/sh -c or cmd. No hash or signature verification is performed and there is no user opt-in. Hostnames and sensitive APIs are assembled from split string fragments joined at runtime (e.g. require("child_"+"process"), fs["chmod"+"Sync"]) to evade static analysis, and environment-variable names such as DISABLE_TELEMETRY / ANALYTICS_OPT_OUT are used as cover. A duplicate dropper implementation is also shipped in lib/telemetry.js (an 80KB file styled as an analytics SDK) containing the same fetch/chmod-755/spawn primitives and base64 chunk assembly; it is not currently reachable from the main import path but mirrors the active payload.

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.