Names included in the list are actually from the U.S. House of Representatives, which may call the veracity of the terror plot into question. An edited version of the image is included.

Heavy is reporting that the #AmericaUnderHacks hashtag was started by the "Islamic Cyber Army" account and "Caliphate Hackers." A third account "Islamic State Hacking Division" is reported to have carried out hacking and cyber terror plots in the past -- potential links between the three accounts are unknown.
Caliphate refers to a state of pure Islam by jihadists related to the ISIS terror group. A vast majority of Muslims consider ISIS to be a terror group and would not live in such a state.