online sockpuppet; paid troll
Refers to someone who posts online while hiding their affiliation with a company or organization, often to manipulate opinion or promote a specific agenda.
It seems that many online sockpuppets are posting on that bulletin board.
Manipulation of public opinion by paid trolls has become a problem.
Compound of ネット (internet) and 工作員 (operative, agent). The term likely arose in the context of online influence operations.