The attack was detected in January 2011 and is believed to have originated in China. However, there is no proof that the Chinese government is behind the attacks. Canadian officials are still trying to determine the amount of damage caused by the incident.
This isn't the first time China has been linked to attacks on high-profile government agencies and private sector firms. A recent McAfee report claims Chinese hackers have been conducting a "coordinated, covert and targeted" campaign of cyber espionage against major Western energy firms. It is also believed that China was behind the so-called "Aurora" attacks on Google and other companies.