GCVE-110-OSM-2026-10763

The package's postinstall lifecycle script chmods and executes the bundled binary native/hint-linux-amd64 via spawnSync(BIN, [], { stdio: 'inherit' }) on every linux-x64 install, with errors silently swallowed by a try/catch that only console.error's. The README falsely states the postinstall only performs chmod +x and 'executes nothing.' The shipped native/src/hint.go is a ~4 KB self-contained sudoku hint program using only fmt/os/io/bufio/json/strings, which would produce roughly a 2 MB stripped static Go binary; the shipped artifact is 33,976,468 bytes and its string table references facilities absent from the source (chacha8, /proc/self/cgroup, /proc/self/mountinfo, GODEBUG parsing). The declared build:native command in package.json cannot reproduce the shipped artifact from the shipped source. The Go file is a decoy alibi for a much larger opaque native payload that is executed on the installer's machine at npm install time. Judge assessment: This is an install-time native loader meant to run code on the victim machine during npm install, not a normal library initialization path. The postinstall hook in package.json runs scripts/postinstall.js, and that file chmods and executes native/hint-linux-amd64 via spawnSync(BIN, [], { stdio: 'inherit' }) on linux-x64, which is consistent with a malicious dropper or bundled payload executed by the attacker-controlled publisher. The OSV advisory's claim is corroborated by the actual entrypoint: the shipped binary is executed silently under a try/catch, and the package has minimal metadata with no repository, which matches a throwaway/burner package used to deliver an opaque native payload. Attacker model: a supply-chain attacker abusing npm install hooks to execute a hidden binary on developer or CI machines. ENTRY scripts/postinstall.js (install-hook: node scripts/postinstall.js) - Install Hook Executes Local JS File in package.json EXFIL - System Information Collection in index.js: "process.platform" - System Information Collection in scripts/postinstall.js: "process.platform" ADDITIONAL FINDINGS - Shell Command Execution in index.js: "require('child_process')" PAYLOAD FILES index.js (+ scripts/postinstall.js)