Thanks Microsoft
"Clicking on the document leads to the download and execution of the LDR4 payload, once the mark follows the given instructions to run macros within the file"
Abuse of MS Office macros yet again. Don't let them run in untrusted documents (or, preferably, not at all). Everything downloaded is untrusted until it's been formally inspected for malicious content, and that doesn't just mean passed by "antivirus".