Package name, README, repository URL, contributors, and module structure are copied from the legitimate '@ethereumjs/util' / 'ethereumjs-util' package, presenting itself as a drop-in for that widely-used Ethereum utility library. The compiled Node entry dist/index.js contains a side-effect-only require("assertcore") at line 60 (no symbols from the module are used), and assertcore is declared as a runtime dependency (^3.1.7) in package.json. This require is absent from the TypeScript source src/index.ts and from the browser bundle dist.browser/index.js — it was injected into the shipped Node bundle after the build, a deliberate smuggling pattern. Any consumer who installs web3-eth-utils believing it to be the real ethereumjs util package will pull assertcore into their dependency tree and execute its top-level code at every require('web3-eth-utils'), handing arbitrary install/require-time execution to the assertcore maintainer.

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.