MAL-2026-4691 Malicious code in testnpmnmp (npm)

package.json declares "preinstall": "./scripts/postbuild", where scripts/postbuild is a 976,568-byte unsigned, unhashed, unversioned Linux ELF executable shipped in the tarball. The package's only JavaScript source (src/index.js) is a trivial stub that exports () => { console.log("hello") }, with the bundled output (dist/index.cjs.js) matching. Nothing in the package's stated Arweave/Warp-contracts wrapper purpose justifies a native executable, and the binary's embedded strings (LIBBPF_0.0, PTRACE, NETLINK, HTTP/1.1, USERPROFILE, RSA_PKCS1_, Ed25519) indicate credential-handling and network-agent capabilities rather than build tooling. On npm install, the binary runs with the installer's privileges before any user inspection; the JS stub is a cover for shipping and executing arbitrary native code. The package name testnpmnmp and stub source further indicate a throwaway dropper rather than a real library.

This package was compromised as part of the IronWorm campaign. This campaign executes a malicious binary payload during installation via a preinstall hook. The payload is a Rust-built infostealer that targets developer environments, scanning for and harvesting credentials related to cloud providers, object storage, databases, source-control, package registries, and AI developer tools. It also targets cryptocurrency wallets, specifically injecting a malicious JavaScript hook into the Exodus desktop wallet to capture passwords and recovery phrases. Furthermore, the malware exhibits worm-like behavior by stealing GitHub and NPM credentials to push malicious updates to the victim's repositories and publish trojanized packages, and it uses an eBPF-based kernel rootkit to hide its processes and network connections on Linux systems.