MAL-2026-15625 Malicious code in evilpostinstall (npm)

The package's postinstall lifecycle hook pipes the output of env through nc to a host reconstructed at install time from the package version string via cut -b 2-4 and cut -b 5-. For version 4127000.0.1 the destination decodes to 127.0.0.1:888; the sibling artifact evilpostinstall-192.168.1.100.tgz uses the same slicing scheme to target 192.168.1.100. On npm install, the full installer environment - including any CI secrets, tokens, and API keys present in environment variables - is transmitted to the reconstructed host over TCP port 888. package.json also declares a self-referencing dependency evilpostinstall: ^4192168.1.100, whose version field encodes a second destination IP under the same scheme, causing npm to resolve and install an additional package instance whose own postinstall repeats the exfiltration against that address. The destination is deliberately hidden from static scanners by being reconstructed from the version field rather than written as an IP literal, and no source files are shipped - the manifest itself is the payload.

The OpenSSF Package Analysis project identified 'evilpostinstall' @ 4127000.0.1 (npm) as malicious.

It is considered malicious because:

• The package executes one or more commands associated with malicious behavior.