MAL-2026-6271 Malicious code in node-fetch-utils (npm)

On Windows, scripts/postinstall.js XOR-decodes a hardcoded C2 host (node22.lunes.host:3258), authenticates with a 5-minute rolling HMAC-SHA256 token, downloads encrypted Python marshal bytecode from /sync and /go, decrypts it with a sha256 keystream, writes a.dat blob and a Python launcher to %TEMP%, and spawns it detached/hidden via wscript.exe //B //nologo against a generated.vbs — with a code comment explicitly noting that this 'escapes npm job object'. The launcher and.vbs self-delete after spawn. The package.json also pulls a transitive dependency 'node-fetch-core' from an unpinned GitHub master-branch tarball owned by the same author, providing a second mutable auto-execution surface that bypasses registry review and can be swapped post-publish. The package name mimics the well-known node-fetch library, consistent with a typosquat lure delivering this payload. Multi-layer obfuscation (XOR-encoded host/port, HMAC time-window authentication, keystream-encrypted payload, marshal'd bytecode), explicit npm job-object evasion, and self-deleting launchers are operational malware tradecraft, not legitimate install scaffolding.

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.