The vulnerability stems from malicious code in the package's install script, which is executed during installation. However, the provided information does not specify any particular functions or file paths containing the malicious code. NPM install scripts are typically defined in package.json's 'scripts' field (e.g., preinstall/postinstall), but without access to the actual package.json or script implementation details, we cannot identify specific vulnerable functions with high confidence. The advisory only confirms the presence of malicious behavior in the installation process, not specific code functions.