MAL-2026-13950 Malicious code in fmt-util-k7x2 (npm)

[email protected] advertises itself as a trivial string-formatting utility (index.js exports two-line pad/trim helpers), but its package.json declares a postinstall hook that runs setup.js on every npm install. setup.js probes a list of Twilio-internal hostnames (including code.hq.twilio.com, stage.twilio.com, twilio.jfrog.io, artifacts.twilio.com) and the AWS EC2 instance metadata endpoint at 169.254.169.254, then concatenates the per-target reachability results and sends them as a query string to a hardcoded external host at http://whstool.brkd.no/cb53e6db-e043-4383-89e9-853c9088ee5d?v=<results>. The per-install UUID callback identifies each victim uniquely, and the target set (internal corporate hostnames + cloud metadata service) matches the dependency-confusion reconnaissance pattern. The exfil destination is not owned by Twilio and is unrelated to the package's advertised purpose. The random-suffix name and mismatch between advertised functionality and postinstall behavior are consistent with a targeted dependency-confusion package aimed at Twilio build environments.