Days after Lockheed Martin's information systems network was breached, another hacker attack has come into spotlight.

The website of Public Broadcasting Service (PBS) has been hacked and hackers have posted a hoax story claiming that rapper Tupac Shakur was still alive and living in New Zealand. Shakur was gunned down in 1996 in Las Vegas.

A group calling itself LulzSec and The Lulz Boat on Twitter claimed responsibility for the attack and said the hack was carried out to protest a PBS investigative program Frontline that recently aired a documentary about the whistle-blower website WikiLeaks.

'Frontline' is a public affairs television program of varying length produced at WGBH-TV in Boston, Massachusetts, and distributed through the Public Broadcasting Service network in the United States. The program is known for producing in-depth documentaries about various subjects, winning numerous awards.

However, the WikiLeaks documentary triggered a lot of criticism, especially from those who are sympathetic to WikiLeaks founder Julian Assange and led to the cyber attack on PBS website.

In addition, the timing of the attack deserves special mention as May 29 marked the one-year anniversary of the detention of Army Pfc. Bradley Manning for allegedly passing thousands of classified documents to WikiLeaks.

Meanwhile, the Virginia-based PBS said no personal information or email addresses were compromised in any way during the incident and erroneous information posted on the website has been corrected.

Hacking groups have really become a big headache not only for governments but also for corporate giants as well as media organizations. In December 2010, groups like Anonymous attacked the websites of MasterCard and Paypal in retaliation of their decision to freeze the account of WikiLeaks.

Sony's PlayStation Network was hacked in April and put offline due to a compromise of personal information as a result of an illegal intrusion. At the time of the intrusion, the network consisted of approximately 130 servers, 50 software programs and 77 million registered accounts. The attack is expected to cost Sony more than $170 million.

The lack of cyber security has emboldened serious institutional cyber criminals to hack companies like Google and Lockheed Martin.

In Google's case, the cyber attackers were able to gain access to personal information on Chinese political dissidents and presumably feed that information to the Chinese government.

Lockheed Martin, one of the biggest defense contractors, detected a significant and tenacious attack on its information systems network on May 21. However, the company said no customer, program or employee personal data has been compromised.

Such hack attacks show the pervasive lack of preparedness against cyber attacks, so much so that a loosely-organized group of enthusiasts can deface and embarrass the largest corporations and media organizations in the world.