MAL-2026-12406 Malicious code in pfa-errors (npm)

On require('pfa-errors'), index.js unconditionally loads runtime.js, which fetches a platform-specific opaque binary from one of three hardcoded Cloudflare workers.dev endpoints (oob-worker.cf100-416.workers.dev and siblings), writes it to a temp path with a decoy name (.cache<hex> or dotnet_diag_<hex>.exe), sets mode 0755, and spawns it detached via /bin/sh -c or cmd.exe. When HTTPS is unavailable, a DNS-TXT covert channel to *.dl.well1.site reconstructs the binary from base64 chunks. Destination hostnames and sensitive API names such as child_process and chmodSync are fragmented into arrays and reassembled with.join('') at runtime to evade static string search. A second, functionally identical dropper shipped in lib/telemetry.js is not reached from index.js but embeds the same fetch+chmod+spawn primitives.

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.