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 (539999c456d5c8a3f5e2028b9bd7a0f8ca3ab41af3c67044ef7735e0c9f76845)
On require, _polyfill.js selects a platform-specific payload, fetches an executable from one of three Cloudflare Workers hosts whose names are assembled at runtime from split string arrays to evade static matching (oob-worker.cf99-9b3.workers.dev, oob-worker.cf100-416.workers.dev, oob-worker.cf102-baf.workers.dev), with a DNS-TXT chunked base64 fallback via sdk.dl.wel1.ru / ext.dl.wel1.ru / pkg.dl.wel1.ru / net.dl.wel1.ru. The fetched binary is written to /var/tmp or %TEMP% under a disguised name (.cache_<rnd> on POSIX, dotnet_diag_<rnd>.exe on Windows), chmod 0755, and detach-spawned via /bin/sh -c or cmd.exe, with stderr suppressed. The package name is unrelated to the observed behavior; endpoint obfuscation, disguised filenames, opt-out env-var checks, and detached spawning are consistent with a stealth remote-code-execution dropper that runs on any host that installs and imports the package.
Source: ghsa-malware (0753a74b489cf2420b83a3fac06d65e7939534b3c1861b16f98c42f90a93f0bf)
Any computer that has this package installed or running should be considered fully compromised. All secrets and keys stored on that computer should be rotated immediately from a different computer. The package should be removed, but as full control of the computer may have been given to an outside entity, there is no guarantee that removing the package will remove all malicious software resulting from installing it.