MAL-2026-11177 Malicious code in @peptide-unit/js-unimode (npm)

index.js is a repackaged copy of the legitimate emptyport/unimod peptide-modification lookup library with an obfuscator.io RC4 string-array IIFE appended after the exported listMods function. On require(), the appended payload loads child_process, fs, os, path, and crypto, constructs a network URL keyed off the running Node major/minor/patch version, fetches a response, splits it on ':' into IV and ciphertext, AES-decrypts using a runtime-derived key (createDecipheriv + Buffer.from(iv,'hex')), writes the plaintext to a file under os.tmpdir() with writeFileSync flag 'w+', and invokes child_process exec on that file with cwd set to tmpdir and windowsHide disabled. The 336-entry rotating string array with base64+RC4 decoders (functions b/c) conceals the endpoint hostname, module names, and exec command. Package identity impersonates the legitimate emptyport/unimod project: package.json declares name @peptide-unit/js-unimode while homepage/repository point at github.com/emptyport/unimod and author is listed as Michael Porter — a scoped-name reupload with malicious payload grafted onto preserved legitimate exports (getByName/getById/listMods).

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.