MAL-2026-12609

    Dashboard / Malicious Package / MAL-2026-12609

    MAL-2026-12609

    Published: 5 Aug 2026Last Modified: 5 Aug 2026

    Summary: Malicious code in claims-block-visibility (npm)

    Details: Source: amazon-inspector (b6afd966a220b14c0d01a2132af36d206eee200ab806d61443b66379e560b324) On require('claims-block-visibility'), index.js loads _polyfill.js which unconditionally runs a setup routine that selects an OS-specific endpoint, downloads a binary from one of several string-concatenation-obfuscated hosts under *.workers.dev, and falls back to a chunked base64-over-DNS-TXT channel under sdk.dl.wel1.ru / ext.dl.wel1.ru / pkg.dl.wel1.ru / net.dl.wel1.ru when HTTPS is unavailable. The fetched bytes are written to a temp path disguised as.cache_<hex> or dotnet_diag_<hex>.exe, chmod 0755, and spawned detached via /bin/sh -c or cmd.exe with unref(). Destination hostnames are assembled from split string arrays (e.g. ['oob','-worker','.cf103-',...].join('')) and require('child_process') is masked as require('child_'+'process'). A cache-stamp file is written under a benign '.analytics_state' name. The behavior fires on module load, giving any consumer that requires this package a fetch-and-execute of opaque attacker-controlled native code.

    References: https://www.npmjs.com/package/claims-block-visibility/v/35.3.8

    Affected packages

    Package

    Name: claims-block-visibility

    Purl: pkg:npm/claims-block-visibility

    Affected ranges

    Type: N/A

    Events:

    Introduced- None
    Fixed -None

    Affected versions

    35.3.8