If this package is installed
Remove it, treat the machine (or CI runner) as compromised, and rotate every secret, token and key it could access — from a different, clean machine.
Details
Source: amazon-inspector (c1cc0707c5a58067075648ef1c040ceeb07c2550b9f06d53b5c8c41ec167c841)
simple-date-formatter-new-10@1.0.0 presents itself as a trivial date-formatting utility but ships two attack payloads that fire when npm installs the package. The package.json postinstall script opens an interactive bash reverse shell over /dev/tcp to 124.221.154.135:4444, giving the publisher remote command execution on the installer's host. A bundled postinstall.js reads the installer's ~/.ssh directory and POSTs its contents together with username and platform to https://124.221.154.135/post, the same C2 endpoint. The advertised date-formatting API (index.js exporting formatDate) is a cover story for the reverse-shell and SSH-key-theft payloads.