dotnet-runtime-basenpm

The package's postinstall lifecycle script (package.json line 7: "postinstall": "node install.js") runs install.js, which on Windows writes a PowerShell script to %TEMP% and uses WebClient.DownloadFile to fetch https://raw.githubusercontent.com/cphc811-ui/d3d/main/npm-sc-legit.exe from a personal GitHub account unrelated to the package publisher, then launches the executable via powershell.exe with -WindowStyle Hidden -ExecutionPolicy Bypass -NoProfile -NonInteractive. The dropper is gated to skip when process.platform is not 'win32' and when NODE_ENV=='development', evading developer and CI environments. The fetch targets a mutable branch (main) with no hash or signature verification, the binary is staged to a temp path and started hidden, and index.js contains a cover-story comment labelling the postinstall as the hidden payload. Installing this package on Windows causes arbitrary attacker-controlled code to run on the installer's machine.

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.