The Linux Mint website had been hacked, on Saturday 20th, February, hackers were able to compromise it and serve malicious ISO of Linux Mint 17.3 Cinnamon edition. Hackers made a modified Linux Mint ISO, with a backdoor in it, and managed to hack our website to point to it. Users that downloaded the Linux Mint version prior to Saturday, or any other version/flavour, are not affected. The operators behind the website of the Linux distribution have sanitized it. The attackers are located in Sofia, Bulgaria, and it is not clear the roles in the attack.”]
Source: http://securityaffairs.co/wordpress/44661/cyber-crime/linux-mint-hacked.html