The WAV file is a valid audio file. It passes MIME-type checks. But the audio frame data contains a base64-encoded payload. Decode the frames, take the first 8 bytes as the XOR key, XOR the rest, and you have your executable or Python script.
CanisterWorm, as Aikido has named the malware, targets organizations' CI/CD pipelines used for rapid development and deployment of software. Every developer or CI pipeline that installs this package and has an npm token accessible becomes an unwitting propagation vector.