It is an acronym for Curve-Tor-Bitcoin-Locker, a type of file-encrypting ransomware, based on elliptic curves, with a malicious server placed in onion-domain (TOR). The cyberattack released in 2014 and infected a high number of users because of its multi-lingual adaptations. The infection spread through aggressive spam campaigns and the strategy of recruiting malicious actors that received a percentage of the profits in Bitcoins.