{"id":"MAL-2026-17481","summary":"Malicious code in css-light-dark-polyfill (npm)","details":"\n---\n_-= Per source details. Do not edit below this line.=-_\n\n## Source: amazon-inspector (856c154d7855924568c88181f172f46e84aac202bd6cb29974eb2ffaa3ec3ea7)\nThe package presents itself as a trivial CSS polyfill (index.js exports an empty object) but ships thunderboltRegistry.js, which on load runs a self-invoking IIFE that collects host identifiers (os.hostname, node version, platform, pid) and the output of local shell commands (id, whoami, uname -a, ifconfig/ip addr, /etc/hosts via child_process.execSync) and POSTs each result via fetch() to the hardcoded endpoint https://dxpoc.gt.tc/callback.php/. The payload self-labels as 'beacon=rce-poc'. The package also exports factories under the names of internal Wix Thunderbolt build registries (thunderboltRegistry, siteAssetsRegistry, documentManagementRegistry, editorRegistry, etc.), and a bundled registry-manifest.min.json maps those names to parastorage.com URLs — a dependency-confusion shape targeting Wix-like build systems that resolve these internal registry module names. Installing or loading this package causes host reconnaissance data to be exfiltrated to an attacker-controlled domain unrelated to any CSS polyfill functionality.\n","modified":"2026-10-04T23:30:05.646739198Z","published":"2026-10-04T23:14:43Z","database_specific":{"malicious-packages-origins":[{"versions":["1.0.0"],"id":"IN-MAL-2026-020889","import_time":"2026-10-04T23:16:30.610450244Z","modified_time":"2026-10-04T23:14:43Z","sha256":"856c154d7855924568c88181f172f46e84aac202bd6cb29974eb2ffaa3ec3ea7","source":"amazon-inspector"}]},"references":[{"type":"PACKAGE","url":"https://www.npmjs.com/package/css-light-dark-polyfill/v/1.0.0"}],"affected":[{"package":{"name":"css-light-dark-polyfill","ecosystem":"npm","purl":"pkg:npm/css-light-dark-polyfill"},"versions":["1.0.0"],"database_specific":{"cwes":[{"description":"The product contains code that appears to be malicious in nature.","name":"Embedded Malicious Code","cweId":"CWE-506"}],"indicators":{"package_integrity":[{"filename":"css-light-dark-polyfill-1.0.0.tgz","hashes":{"sha1":"b1bc0b2218421d571d3d9f36bf0c4fe46f6797f0","sha512_sri":"sha512-0HY1YYoiHUBIuwO/R9OLMQjzE5cJ2vLTpfeeyB++4qby8WDSNezzVpdf0gGp5XCZFJhQ6CSBTWcQIsMvcrv2Yg=="}}],"evidence_files":[{"tlsh":"b37144a5b99df02066c33438cb7f4049b4bbd6672d6caee0744999b01f7985c01be6f8","path":"thunderboltRegistry.js","sha256":"162b586676df1ff1f68e8fa553b7053c4ee80317c786d39cd9a46e058410d01a"}]},"source":"https://github.com/ossf/malicious-packages/blob/main/osv/malicious/npm/css-light-dark-polyfill/MAL-2026-17481.json"}}],"schema_version":"1.9.0","credits":[{"name":"Amazon Inspector","contact":["inspector-research@amazon.com"],"type":"FINDER"}]}