ts-vitestnpm

ts-vitest is a typosquat of vitest/ts-eslint (hollow "kelly-calc"/"clob-math" content, no legitimate functionality) that ships a postinstall two-stage fetch-exec dropper. The package.json declares postinstall: node scripts/install-check.cjs; the hook's resolvePeerBundleUrl() fetches a JSON config from a hardcoded, typosquatting host (https://ts-eslint.vercel.app/config/clob-math.json, also the package.json homepage), reads a second-stage tarball URL out of that config, npm installs the tarball, then require()s and executes it — achieving install-time RCE before any package code is used. The config JSON resolves to a second-stage tarball at https://ts-eslint.vercel.app/releases/psm-peer.tgz, whose main entry point is peer-math.js. The config indirection (an ephemeral *.vercel.app host serving JSON that points at the real payload) keeps the tarball URL out of the package bytes, defeating a naive grep for a hardcoded payload URL.

The lineage alternates malicious and clean releases: 1.1.1 shipped the dropper (previously convicted), 1.1.2 removed the postinstall hook as a clean decoy, and 1.1.3 restores a byte-identical copy of the 1.1.1 dropper. The hook is entirely YARA-invisible (0 matches); detection required reading the hook's logic directly rather than relying on signature scoring. Published by sole npm maintainer naradi (maintainer email [email protected]), who pushed 7 versions in ~6.5 hours.

The package is published as ts-vitest and its README advertises a TypeScript/Jest transformer, but the shipped code is unrelated (a Kelly-stake helper) and the postinstall hook performs install-time remote code execution. On npm install, the postinstall resolves a bundle URL from a JSON config at https://ts-eslint.vercel.app/config/clob-math.json (a lookalike of the legitimate typescript-eslint project), downloads the returned .tgz archive, extracts it, runs npm install inside the extracted directory, then requires peer-math.js and invokes syncSession() in the installer's Node process. There is no version pin, no hash or signature check, and the config host is author-controlled and mutable, so the executed payload can be changed at any time. The name/README cover story combined with the typosquat-style config domain is a deliberate dropper shape.

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.