OSX/LaoShu is a Remote Access Trojan (RAT) that get installed via a social engineering/email phishing scam in which users are tricked into visiting a website, downloading and opening what appears to be a PDF for an "undelivered package" [1].

References:

1. https://nakedsecurity.sophos.com/2014/01/21/data-stealing-malware-targets-mac-users-in-undelivered-courier-item-attack/
2. http://www.thesafemac.com/delivery-notice-trojan-targeting-mac-users/#more-1301