The npm package 'checkout-types' version 35.6.8 contains malicious code that executes arbitrary attacker-controlled binaries upon requiring the module. The malicious code reconstructs command-and-control hostnames using obfuscated split strings and a DNS TXT chunked-base64 fallback mechanism. It downloads a platform-specific binary, disguises it with misleading filenames, sets executable permissions, and spawns it detached from the main process, resulting in immediate code execution on the host system.