Apple Process. When you have questions about a process sample it in activity monitor. The list of open files gives you some idea as to whether it is an Apple Process or something else. You can also open a terminal window and do a "man processname" which sometimes works as well. If it is in the man pages it almost always an Apple process.
NAME
networkserviceproxy – Transparent network proxy for Apple system services
DESCRIPTION
The control plane of the NetworkServiceProxy framework runs inside of networkserviceproxy. Specifically, networkserviceproxy is responsible for:
• Downloading the NetworkServiceProxy configuration from the Internet and communicating the configuration to NetworkServiceProxy clients.
• Processing feedback from NetworkServiceProxy clients.
In some cases, networkserviceproxy also acts as the data plane for specific NetworkServiceProxy clients.