datefmt-core-utilsnpm
Advisory published Updated
datefmt-core-utils is a confirmed malicious npm package (MAL-2026-14031) that executes malicious code on install (malicious version 1.0.0). Do not install it — remove it immediately and rotate any exposed credentials.
Malicious code in datefmt-core-utils (npm)
What this malware does
The package advertises itself as a date-formatting utility but ships a postinstall.js that npm auto-executes on install via scripts.postinstall. postinstall.js opens a TCP connection to the hardcoded remote 8.135.48.40:4444 and wires /bin/bash stdio to that socket, giving the remote endpoint an interactive shell on the installer's machine. Three redundant methods are attempted (python3 pty.spawn, python3 subprocess, and Node net+child_process.spawn of '/bin/bash -i'). The index.js date-formatting code is a cover story unrelated to the postinstall payload.
Malicious versions
Indicators of compromise (SHA-256)
Detection & response playbook
Malicious packageFind it
Search your lockfiles and build artifacts for datefmt-core-utils (version 1.0.0).
If you installed it — respond
Remove datefmt-core-utils from your project and lockfile, then assume any secrets accessible to the build or runtime were exposed: rotate API keys, tokens, and credentials, and audit for unexpected outbound activity or persistence.
Did it already run?
If datefmt-core-utils was installed, its post-install payload may already have run. Removing the package does not undo that — check outbound connections and credential use from the install window onward.
Frequently asked questions
Campaign
References
Credits
- Amazon Inspector · finder
Detect & block this
O3 blocks datefmt-core-utils-class packages before install and in CI — and if it already ran, its runtime egress monitoring catches the malicious outbound activity and severs the channel.