According to Vice, hackers had first purchased the stolen cookies (Slack site cookies) for just $10 and using those cookies hackers logged into the Slack channel, which was used by the EA.
What Are Cookies?
Cookies are text files with small pieces of data — like a username and password — that are used to identify your computer as you use a computer network. Specific cookies known as HTTP cookies are used to identify specific users and improve your web browsing experience.
Data stored in a cookie is created by the server upon your connection. This data is labelled with an ID unique to you and your computer.
When the cookie is exchanged between your computer and the network server, the server reads the ID and knows what information to specifically serve to you.
Data stored in a cookie is created by the server upon your connection. This data is labelled with an ID unique to you and your computer.
When the cookie is exchanged between your computer and the network server, the server reads the ID and knows what information to specifically serve to you.
Story Continues.......
After logging in to the Slack channel, hackers had contacted the IT support team with the request of
a multifactor authentication token to gain access to the EA Network. Social engineering bypasses all technologies, including firewalls. — by Kevin Mitnick
After getting token hackers accessed the EA corporate network, where they found a service for EA developers for compiling games. In the network, hackers created a virtual machine giving them more visibility into the network, and then accessed one more service and downloaded game source code.
Furthermore, Vice mentioned that hackers had provided a series of documents they say were stolen as part of the hack. They include an assortment of material on PlayStation VR, how EA creates digital crowds in the FIFA games, and documents about AI in games.