Over 2 years old crypto puzzle which i mentioned here has been solved. In the picture above, author has hidden private key to the blockchain address which contained 5 BTC. Image in the high resultion you can find here https://imgur.com/OSpEZtA.
Whole amount from the address was transfered on 31.01, puzzle author confirmed that someone had solved the puzzle.

Deliberately implemented error in the private key generator

Anonymour hacker who uses fitwear pseudonim on the reddit has discovered that many private keys for the bitcoin wallets were generated using public key of another wallet forming a chain. Maybe some bitcoin exchange or address generator has that bug implemented on purpose so the author could steal from users. More about you can find in the following reddit discussions https://www.reddit.com/r/Bitcoin/comments/7cw2uw/how_blockchaininfo_stole_65000_from_me/