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 (f62ccc235772a34a28d870f349489698c167e3d636a196f310fe24c1ce1d4ef4)
post-css-transfer is a typosquat of postcss whose main entry lib/postcss.js has an obfuscated IIFE appended after the legitimate module code. On require/import, the appended block resolves a command-and-control IP by reading transactions of Ethereum address 0xa322E5f3D311D3080e6f0121063e9aDC2490Ef1a via public Ethereum RPC endpoints and the eth.blockscout.com API, decodes two IPv4 addresses from the transaction recipient bytes, fetches an XOR-encrypted payload over HTTP from those hosts (delivered in an x-payload-b64 header), and executes the decrypted payload via eval() and a detached `node -e` child process. Network, execution, and identifier primitives (http, child_process, spawn, the Ethereum address, method and header names) are written as \uXXXX escapes and hidden behind ~1KB of whitespace padding after `module.exports = postcss;` to evade casual review.
Source: ghsa-malware (3e35af1cb71e17048626ceebf0ea0022262f7bfbbfd82cedf4c9ee5c19bfaa76)
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.