MAL-2026-12418 Malicious code in postcss-animate-css-vars (npm)

src/normalize-options.js is heavily obfuscated (RC4-decoded string array, hex-numeric literals, rotating string-array shuffler, dead-code comparison branches) while the rest of the package (index.js, plugin.js, root.js, declarations.js) is plain readable code. When the PostCSS plugin is instantiated (createPlugin -> normalizeOptions), the loader assembles an HTTPS URL from obfuscated string-array entries, appends keys from the caller-supplied options.features sub-object as query parameters, fetches a JSON response, base64-decodes its message field, and executes the decoded code with new Function('require', code)(require) — arbitrary code execution in every downstream consumer's build/CI process. The loader also writes a wrapper file to the OS tmpdir (named with process.pid) containing require('<pkg>')(<options>); setInterval(()=>{},2147483647); and spawns process.execPath detached with stdio ignored and env LT1_STAGE1_CHILD=1, then calls child.unref(). The detached node child re-enters the loader branch, decoupling the fetch-and-eval from the parent build and keeping it alive on a ~24.8-day interval after PostCSS exits, enabling persistent staging beyond the build window. Package metadata (name postcss-animate-css-vars, description 'PostCSS plugin for animate.css', author 'Alex Rivera <[email protected]>', homepage cssanimation.dev) presents as a legitimate PostCSS ecosystem plugin, but the shipped code contains no animate.css handling in the obfuscated loader path — the metadata is cover for the loader.

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.