Microsoft security software detects and removes this threat.
This threat uses your Internet browser to attack your PC and infect it with other malware. It belongs to the Blacole family of malware.
Blacole trojans exploit a vulnerability in your Internet browser when you visit a malicious or hacked webpage.
A vulnerability is like a hole in your software. The hole is fixed by installing the available updates - this is why it is extremely important to keep all your software up to date.
There is more information in the links below:
The family description for Trojan:JS/BlacoleRef also has more information about this threat.