According to security experts the BlackEnergy malware was a key element of the attack against Ukrainian power grid that caused the power outage. The attack consisted of at least three components: the malware, a denial of service to the phone systems, and the missing piece of evidence of the final cause of the impact. Unknown attackers used a wiper utility called KillDisk, and launched a denial-of-service on phone lines in order to stop company personnel from receiving customer reports of outages. The malware also appears to have been used to wipe files in an attempt to deny the use of the SCADA system for the purposes of restoration.”]
Source: http://securityaffairs.co/wordpress/43483/malware/43483.html