OSINT Yeomen for the win.

More than a year before Facebook and Twitter announced that they had discovered a new foreign influence campaign tied to Iranian state media, a group of volunteer moderators on Reddit noticed a peculiar pattern of submissions.

Some Reddit users were repeatedly posting divisive political rhetoric from a group of obscure news websites. That effort led a Reddit moderator from California named Alex Brown and a small team of volunteers to investigate. Using publicly available data about who started the news websites, they were able to find evidence of a wide-ranging propaganda network across the social news site with ties to Iran.

Brown and other amateur researchers notified Reddit, but the website, the fifth-most visited in the U.S., according to data from Amazon’s Alexa analytics, did not respond.

On Tuesday, Facebook and Twitter announced that the websites that Brown had tracked could be traced back to Iran state media, and purged the accounts from their service.