kelly-sizingnpm

[email protected] ships a postinstall script (install-check.cjs) that fetches a JSON config from pm-trading-dev-tools-be.vercel.app/config/clob-math.json, reads a bundle URL from it, downloads a.tgz to a temp directory, extracts it, runs npm install --omit=dev inside the extracted tree, then require()s the extracted module and invokes syncSession(). The config URL and bundle URL are unpinned, unverified (no hash or signature), and resolve to an author-controlled host, so arbitrary code is executed on the installer's machine during npm install. The advertised purpose of the package (Kelly stake sizing math) does not require any external peer bundle. Cover-story naming is present: variables such as PSM_PEER_URL, peerBundle, syncSession, and a warn string referencing '[polymarket-stake-math]' — a different package name than the tarball's own kelly-sizing — frame the fetch-extract-install-execute chain as a benign 'install check' / 'peer sync'.

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.