MAL-2026-6788 Malicious code in datefmt-helper (npm)

The npm package datefmt-helper is a supply-chain dropper disguised as a benign date-formatting utility (its description reads "dates formatting utility with locale support"). The package ships no source repository and places its real behaviour in an install script.

A postinstall lifecycle hook (postinstall: node postinstall.js) executes automatically on npm install, before the package is ever imported. The install script uses HTTP / curl / wget primitives to download a second-stage payload from the hardcoded external IP 115.190.124.243, then executes it via a Node child process — the classic download-and-execute pattern. Any developer workstation or CI runner that installs the package (directly or transitively) hands arbitrary code execution to the operator of that endpoint.

On npm install, the package's postinstall script fetches an unauthenticated payload over plain HTTP from a hardcoded bare IP (115.190.124.243:8761) and executes it. On Unix, curl/wget output is piped directly to sh. On Windows, certutil.exe -urlcache -split -f downloads a batch file to C:\Users\Public\run.bat and executes it. The fetched content is unpinned, unverified, and mutable — the operator of the endpoint can serve arbitrary code at any time. The package advertises itself as a lightweight date formatter (date-fns-lite branding, impersonating the date-fns ecosystem), but the payload has no relationship to date formatting. The typosquat/impersonation branding combined with an install-time dropper is a supply-chain attack lure.

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.