prettier-sdknpm

Package name prettier-sdk impersonates the top-tier prettier package (~50M weekly downloads), copying its README verbatim and forging metadata (repository: prettier/prettier, homepage: https://prettier.io, author: James Long). The postinstall script node./plugins/preinstall.js base64-decodes a hardcoded URL stored in a misleadingly-named variable HASH_KEY = "aHR0cHM6Ly9qc29ua2VlcGVyLmNvbS9iLzM2S0VN" (decodes to https://jsonkeeper.com/b/36KEM, an anonymous mutable paste service), HTTP GETs it via axios, and pipes the response body's cookie field to the stdin of a detached node process via spawn('node', [], { detached: true,... }) followed by child.stdin.write(s1); child.unref(). This executes arbitrary attacker-controlled JavaScript on every installer's machine at npm install time, with no integrity check, from a host the attacker can mutate at will. Three independent block signals stack: typosquat-with-malicious-payload against a top-100 package, install-time fetch-and-execute from an anonymous paste host, and base64 obfuscation of the C2 URL.

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.