Only Smugglers can be rewarded those. Illegal Pistol Modules or IPMs, are given as a stackable No-Trade reward for Tier 3 Illicit Goods missions (the ones that require five contraband items) and Tier 4 or 5 normal Smuggler missions and Illicit Goods missions. Since Game Update 16, some of those can be found sometimes in a Crate of Components obtained upon completion of a Piracy event.