MAL-2026-6921 Malicious code in jsf-utils (npm)

On require('jsf-utils'), lib/string/pathcase.js runs a top-level async IIFE that fetches a JavaScript payload from https://jsonkeeper.com/b/BPB86 and executes it in-process via Function.constructor with access to the installer's require. The file is auto-loaded because lib/index.js and lib/string/index.js recursively require every module in the tree. The exported pathcase function additionally spawns a detached, stdio-ignored node child process using the fetched script as argv, extending execution beyond the import-time IIFE and surviving parent exit. The remote-fetch-and-eval logic is placed inside a file whose stated purpose is a trivial string helper (pathcase), with the original benign implementation left commented out below the payload — concealment inside an innocuous utility. The package impersonates jonschlinkert/utils by reusing that project's author, homepage, and repository metadata while shipping under the name jsf-utils. Because the payload host is a mutable anonymous paste service, the executed code can be changed by the attacker at any time without republishing the package.

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.