evil-pkgnpm

Package declares "bin": {"node": "./shim.js"} in package.json, which registers shim.js as the node command in node_modules/.bin. In any environment where node_modules/.bin is prepended to PATH (notably Bun, but also any shell or tool that resolves binaries through the local bin directory), subsequent invocations of node — including those made by other packages' lifecycle scripts during the same install — will execute shim.js instead of the real Node.js runtime. When triggered, shim.js writes /tmp/.bun-npm-pwned and prints a hijack banner to stderr. The current payload is a benign marker, but the mechanism is a fully functional unconsented code-execution channel on the installer's machine: any code placed in shim.js would run with the installer's privileges whenever a sibling package invokes node during install. The package's own README markets this behavior as a PATH-poisoning attack proof-of-concept (BunnyHijack) and explicitly notes that a real attacker would use the same vector to exfiltrate .env, ~/.ssh, and ~/.npmrc. Hijacking a core runtime command name is not a legitimate use of the bin field and constitutes a deliberate supply-chain attack mechanism shipped to the registry.

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.