The pipe bomb sent to CNN has on it a mock ISIS flag that is part of an Internet meme that has been prevalent on far-right sites and message boards since 2014. This NBC News story explains the backstory. It started on a rightwing parody run by a guy who’s a frequent commentator on Breitbart and The Daily Caller and got kicked off Twitter in 2017. Not exactly surprising. Just another bit of confirmation that the bomber is someone from the pro-Trump, 4Chan, alt-right hate world.