Researchers say Yahoo data breach came at hands of a cybercrime group, not a nation-state, as Yahoo says. Eastern European cyber crime group did the dirty work of hacking into Yahoo and stealing credentials, researchers say. The researchers say there are two main groups involved: English-speaking cybercriminals, “Hell Forum” and Russian-speaking. A proxy who goes by “tessa88″ brokers deals between the two groups, InfoArmor says. The report says that Hell Forum’s key member was behind hacks of Ashley Madison, AdultFriendFinder, and Turkish National Police.”]
Source: https://www.darkreading.com/attacks-breaches/researchers-shoot-down-yahoo-claim-of-nation-state-hack