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OpenAdvisories
Malicious MAL-2026-12609

claims-block-visibility

npm package · versions 35.3.8

Reported Aug 5, 2026 · Updated Aug 5, 2026

If this package is installed

Remove it, treat the machine (or CI runner) as compromised, and rotate every secret, token and key it could access — from a different, clean machine.

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.