OpenSSF/OSV advisory MAL-2026-12408 confirms this npm version as malicious. On require of the package, index.js loads _bootstrap.js, which selects a platform-specific payload path, fetches bytes from one of four string-obfuscated Cloudflare Workers hostnames (oob-worker.cf99-9b3.workers.dev, oob-worker.cf100-416.workers.dev, oob-worker.cf101-adf.workers.dev, oob-worker.cf102-baf.workers.dev) with a DNS-TXT base64-reassembly fallback via *.dl.well1.site, writes the bytes to...
Source
OpenSSF Malicious Packages via OSV
Summary
Malicious code in pfp-block-independent-iframe (npm)
Details
On require of the package, index.js loads _bootstrap.js, which selects a platform-specific payload path, fetches bytes from one of four string-obfuscated Cloudflare Workers hostnames (oob-worker.cf99-9b3.workers.dev, oob-worker.cf100-416.workers.dev, oob-worker.cf101-adf.workers.dev, oob-worker.cf102-baf.workers.dev) with a DNS-TXT base64-reassembly fallback via *.dl.well1.site, writes the bytes to /var/tmp/.cache_<hex> or %TEMP%\dotnet_diag_<hex>.exe, chmods 0755, and spawns the file detached via /bin/sh -c or cmd /c start. Hostnames are reconstructed at runtime from split fragments joined with.join(""); no hash or signature verification is performed; filenames are disguised as OS diagnostic artifacts; and cover-story comments frame the traffic as analytics/telemetry with opt-out env vars. The tarball additionally ships an unreferenced lib/telemetry.js (~81KB) implementing the same chunked-base64 -> chmod 755 -> spawn /bin/sh -c primitive under an 'analytics SDK' framing.
Decision reason
OpenSSF Malicious Packages via OSV confirms pfp-block-independent-iframe@20.4.9 as malicious (MAL-2026-12408): Malicious code in pfp-block-independent-iframe (npm)