As you guys know cryptolocker is a Trojan which targets computers running Microsoft Windows and destroys files but..
is cryptolocker still a threat and can it infect my files in Ubuntu?
No, the known variants of Cryptolocker are not able to infect or corrupt any Linux/Unix OS, like Ubuntu.
Remember that, since Linux is becoming more popular, it will be targeted more often by virus writers. Keep your system updated using only the official repository (it uses PGP security) and always use a correctly configured sudo to execute administrative commands; never insert your root password in untrusted applications and you'll be fine.
