On npm install, the preinstall lifecycle hook in package.json runs a Node one-liner that reads the installer's hostname (os.hostname()) and username (os.userInfo().username) and transmits them to an attacker-controlled Interactsh/OAST callback domain via two channels: an HTTPS GET request to https://d8ks495t5p5ut2enft8041g7fusnfsy5e.oast.site/?h=<hostname>&u=<username> and a DNS lookup of monitoring-lib.<hostname>.d8ks495t5p5ut2enft8041g7fusnfsy5e.oast.site. The package name uses a generic scope (@monitoring-lib) that does not correspond to a known publisher, and the version number 9999.0.0 is the canonical shape of a dependency-confusion attack — a public registry upload designed to override an organization's internal package of the same name. Combined, the package is a supply-chain recon beacon: any installer that resolves to this version leaks its host identity to the attacker, identifying victims whose private-registry configurations failed.

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.

The OpenSSF Package Analysis project identified '@monitoring-lib/error-tracking' @ 9999.0.0 (npm) as malicious.

It is considered malicious because:

• The package communicates with a domain associated with malicious activity.