This is a virus detection. Viruses are programs that self-replicate recursively, meaning that infected systems spread the virus to other systems, which then propagate the virus further. While many viruses contain a destructive payload, it's quite common for viruses to do nothing more than spread from one system to another.
Indication of Infection
Word caption changed to Username. Tools/Macro menu bar removed.
Methods of Infection
Opening an infected document will directly infect the local Word environment and any document opened thereafter.