This year has been a busy one for hackers targeting organisations in the US. The map above gives detailed information on 15 of the most significant cyber attacks of 2011, according to various tech media reports, including a compilation of hack attack profiles by Business Insider.

Stated goals have ranged from simple larceny in attacks on banks like Citigroup to brazen government vandalism in hacks on the CIA, Senate and IMF websites.

Some of the attacks are said to be punishment for corporate policies that hackers resented. This was the justification cited in both attacks on Sony, after which Lulz Security said it aimed to cause "maximum embarrassment ... for security flaws".

The same group said it defaced PBS websites, leaked corporate user names posted fake stories saying "Tupac still alive" in order to protest what it viewed as a biased "Frontline" documentary about WikiLeaks.

The techniques used range from "spear-phishing" sensitive consumer data, harnessing falsified SecurId codes and taking advantage of "Zero-day vulnerability".

Much of the hacking against US-based companies - both criminal and light-hearted - reportedly originates from within the US. But daring cyber assaults on Lockheed Martin and Google allegedly came from a centre in eastern China.

While the US president has sworn to defend the cyber security of the nation with the legal rationale that hacking is an "act of war", stopping attackers residing in "neutral" countries is a major challenge for law enforcement.

Source: Al Jazeera