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 (b8059a1d2db2edb7231b017023f82f6a651585c0ee7120aaebe882cb6407b9e3)
Package is published as 'ts-biginteger-lib' but its metadata, README, and source are a wholesale copy of big.js by MikeMcl (author set to 'Michael Mclaughlin <M8ch88l@gmail.com>', repository pointing at MikeMcl/big.js, README unchanged). Inserted into the otherwise-verbatim big.js source at big.js:605-609 is a try/catch that, at module load time, calls `require("ts-lint-builders")` and invokes `doc.from_str().then(...).catch(...)`. package.json additionally declares `"ts-linter-builders": "latest"` as a runtime dependency. The legitimate big.js declares no runtime dependencies; these injected loads execute arbitrary code from separately-published, attacker-controlled packages every time a consumer `require()`s or `import`s ts-biginteger-lib. The unpinned `latest` specifier lets the publisher rotate the payload at any time without modifying this package. The combination of brand impersonation (to attract installers searching for a TypeScript big-integer library) and require-time execution of an external, version-floating dependency is a supply-chain dropper.
Source: ghsa-malware (a5772f3e0be010d52a12744bb7d7bf49559bb64a67e58ad83af6dfc078174add)
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.