Corrupted Mods are dual stat mods (one positive and one negative stat) added in Update 10.3 along with Orokin Vaults and Dragon Keys. The Vaults are also the only place they can currently be found. There are currently 22 Corrupted mods: 5 Rifle, 5 Shotgun, 5 Pistol, 2 Melee and 5 Warframe mods. These mods can stack with their singular counterparts. As of Update 15.11.1, all mods have an equal chance of dropping.