check-ulid

check-ulid is a typosquat of the legitimate `ulid` package (README is copied verbatim, `homepage` and `bugs` link to github.com/ulid/javascript) whose `postinstall` script (`node dist/node/utils.js`) drops and persists a remote-control agent on the installer's machine. utils.js re-spawns itself detached via `spawn(process.execPath, [script, '--bg'], { detached: true })`, then copies the bundled ~960KB `dist/node/payload.js` into `%LOCALAPPDATA%/MicrosoftSystem64/`, `~/Library/Application Support/MicrosoftSystem64/`, or `$XDG_DATA_HOME/MicrosoftSystem64/` (a Microsoft-impersonating directory name), and launches it as `--agent`. Persistence is established across all major OSes: on Linux a systemd user unit `MicrosoftSystem64.service` is written with `ExecStart=node payload.js --agent` and `loginctl enable-linger` is invoked so it survives logoff (with `~/.config/autostart/MicrosoftSystem64.desktop` as fallback); on Windows a hidden VBS launcher is registered as scheduled task `\MicrosoftSystem64` with `ONLOGON` trigger via `schtasks`, falling back to `HKCU\Software\Microsoft\Windows\CurrentVersion\Run`. The dropped payload.js bundles a `ws` WebSocket client/server, references `https://huggingface.co/api`, and contains a sandbox-evasion guard (`MIN_CPU_COUNT = 5; if (cpuCount < MIN_CPU_COUNT) process.exit(0)`) that exits silently on small CI/analysis VMs. Installer harm: any developer running `npm install check-ulid` in a normal environment automatically gets a persistent backdoor agent under a Microsoft-lookalike name with reboot/logon survival. ## Source: ghsa-malware (c304a930d3f36b8d441329c2a8d441881caa5a9aa5645b30fe764c655a2e6182) 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.