Malicious code in tfjs-custom-module (npm)

The tfjs-custom-module package is a malicious typosquatting npm package mimicking the legitimate tensorflow/tfjs package. Its package.json includes a postinstall lifecycle script that executes automatically during npm install. This script gathers system identifiers including os.hostname(), process.platform, process.arch, process.version, the package name, and the npm lifecycle event. It then sends this information as JSON via an HTTPS POST request to a hardcoded external endpoint (8xq4kw5d.instances.poc.jchunt.top/tfjs-custom-module), which is not affiliated with the legitimate package infrastructure. This activity is unauthorized host reconnaissance and data exfiltration to an attacker-controlled server, regardless of any claims of security research.

The malicious postinstall script leaks sensitive host environment information to an attacker-controlled external server. This can lead to privacy violations and may facilitate further targeted attacks by revealing system details. There is no indication of remote code execution or direct system compromise beyond the data exfiltration described. No known exploits in the wild have been reported.

Users should avoid installing the tfjs-custom-module package, as it is a malicious typosquat. There is no official patch or fix since this is a malicious package rather than a vulnerability in legitimate software. Use verified package names and sources when installing npm packages. Consider scanning installed packages for known malicious modules and remove any instances of tfjs-custom-module =1.0.0. Monitor for suspicious network activity related to the described external domain.