The recent high-profile email dumps from Wikileaks appear to be obtained through an email "Phishing" scheme that is pervasive. I received the same email around the same time as the target of one of the most visible politically motivated leaks.
These emails are attempting to get targets to click on a link and provide some personal information such as a login or payment credential. It is not always picked up by virus software as you are not being prompted to download anything.
What you can do:
- Be suspicious of any email you receive asking for personal information even if you recognize the sender. Always call the sender to confirm before providing any sensitive information.
- Use a trusted cloud email provider such as Gmail or Office 365 with 2-factor authentication.
- Consider a Chromebook if you are just doing email and cloud based applications. This Google operating system is essentially a web browser and significantly reduces the risk of your device being compromised.