A clever hacker from Germany figured out to exploit a security flaw, which was discovered and announced by Dell's security team, which made it possible to use another computer's storage product to do work for you. By using this flaw, the German hacker managed to mine around 500 million Dogecoins, worth around $600,000.
The hacker has been traced back to a person known as "Folio" on Github, which is a cloud service where developers can post and share their ideas with others, commonly used for cryptocurrency enthusiasts. The security flaw was discovered in 2013 and was fixed by Dell later on, but in the meantime the hacker ultimately used the flaw and gained access to multiple machines and used them to mine for him.
The storage system which had the flaw is known as Synology and if you have been using this in the past, you might have been victim of being hacked and used as a miner for the German. The error is fixed now however, but it is probably once again just a matter of time before hackers figure out a new way to get people to mine for them, without them knowing that they are doing so.
Similar attacks has been done in the past, where a Google Play application used the Android devices to mine coins, as well as Yahoo ads who spread malicious malware on your computer which could be used for the same. For now it seems that this was the most profitable hack mining attack so far in the cryptocurrency community.