Malicious code in date-fmt-utils-helper (npm)
The npm package date-fmt-utils-helper contained malicious code disguised as a date-formatting utility. A postinstall hook executed on npm install established a reverse shell to attacker-controlled infrastructure (8.135.48.40:4444), granting interactive shell access to the installer's machine.
- Disclosed
- Last updated
- Blast radius
- All npm users who installed date-fmt-utils-helper during the malicious distribution window.
- Ecosystems
- Attack vectors
- Affected entities
- date-fmt-utils-helpernpm package containing malicious postinstall hook
The npm package date-fmt-utils-helper was published with malicious intent. While presenting itself as a date-formatting utility, the package's index.js contained only trivial cover code, with source comments explicitly labeling the library as a disguise.\n\nThe package.json included a postinstall hook that executed node postinstall.js upon npm install. This script opened a TCP connection to the hardcoded remote host 8.135.48.40:4444 and piped /bin/sh stdio over the socket, establishing an interactive reverse shell using bash -i >& /dev/tcp/... with python3 pty.spawn fallbacks. This gave the remote attacker interactive shell access on the installer's machine at install time.\n\nOn failure, the script beaconed error details via HTTP GET requests to http://8.135.48.40/shell/failed and /shell/error, confirming the destination as attacker-controlled command-and-control infrastructure.\n\nThe incident was identified and credited to the OpenSSF malicious-packages repository.
Indicators of compromise
- Packages
- date-fmt-utils-helper
- IPs
- 8.135.48.40
Remediation
- Immediately uninstall date-fmt-utils-helper from all systems
- Audit npm install logs to identify when the package was installed
- Assume any machine that installed this package during the malicious distribution window has been compromised; perform forensic analysis and credential rotation
- Review network logs for connections to 8.135.48.40:4444 and HTTP requests to 8.135.48.40/shell/*
- Use npm audit to check for this package in dependency trees
- Consider using npm package signing verification and supply chain security tools to detect similar malicious packages
Sources
- GitHub Advisory GHSA-2x4f-pqw5-v64x · GitHub Advisory Database
Cite this entry
"Malicious code in date-fmt-utils-helper (npm)." supplychainattack.org, Supply Chain Attack Incident Catalog. Disclosed August 13, 2026; last updated August 13, 2026. https://supplychainattack.org/incident/malicious-code-in-date-fmt-utils-helper-npm-2zcaec
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