
While ethical hackers attack a security system to find out vulnerabilities that a malicious hacker could use to his advantage, unethical hackers discreetly wreck havoc on computer systems and steal confidential information.
In the 1970s, the United States government used groups of experts called red teams to hack its own computer systems.
Today, many companies hire ethical hackers to safeguard their vital computer systems.
Here's a look at the world's most famous hackers...
1. Gary McKinnon
Gary McKinnon, a Scottish systems administrator has been accused of the biggest military computer hacking exercise of all times by the US government.
McKinnon is also accused of copying data, account files and passwords into his own computer.
US authorities pegged the cost of tracking and rectifying the problems caused by his hacking at over $700,000.
Image: Gary McKinnon.
Photographs: Reuters.
Last updated on: September 28, 2011 09:28 IST

2. Robert Tappan Morris
Robert Tappan Morris is an American computer scientist, known for creating the first computer worm on the Internet called the Morris Worm in 1988.
He became the first person convicted under the Computer Fraud and Abuse Act.
He is a professor in the department of Electrical Engineering and Computer Science at the Massachusetts Institute of Technology.
Click NEXT to read more...Image: Robert Tappan Morris. Last updated on: September 28, 2011 09:28 IST

3. Kevin David Mitnick
Kevin David Mitnick is a computer security consultant, author, and hacker. In the late 20th century, he was convicted of various computer-related crimes.
When he was 12 years old, Mitnick used social engineering to bypass the punchcard system used in the Los Angeles bus system.
Click NEXT to read on . . .
Image: Kevin David Mitnick. Last updated on: September 28, 2011 09:28 IST

4. Kevin Poulson
Kevin Lee Poulsen, a former black hat cracker, works as senior editor at Wired News.
He is well known for hacking all the telephone lines for Los Angeles radio station KIIS-FM, to make sure that he would be the 102nd caller and win the prize of a Porsche 944 S2.
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Image: Kevin Poulson. Last updated on: September 28, 2011 09:28 IST

5. Jonathan James
Jonathan Joseph James who passed away in May 2008, was an American hacker.
He was the first juvenile to be imprisoned for cybercrime in the United States. He died as a result of a self-inflicted gunshot wound.
Click NEXT to read more...Image: Jonathan James. Last updated on: September 28, 2011 09:28 IST

6. Adrian Lamo
Adrian Lamo a threat analyst gained popularity by hacking into several high-profile computer networks, including those of The New York Times, Yahoo!, and Microsoft. He was arrested in 2003.
Click NEXT to read more...Image: Adrian Lamo. Last updated on: September 28, 2011 09:28 IST

7. Vladimir Levin
Vladimir Levin, a businessman is known for his involvement in attempting to fraudulently transfer $10.7 million via Citibank's computers.
Currently, he does business in Lithuania.
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Image: Vladimir Levin. Last updated on: September 28, 2011 09:28 IST

8. Raphael Gray
Raphael Gray was just 19 when he hacked computer systems around the world in 1999 as part of a multi-million pound credit card mission.
He published credit card details of over 6,500 cards to point out the weak security in consumer web sites.
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Image: Raphael Gray. Last updated on: September 28, 2011 09:28 IST

9. Deceptive Duo
A 20-year-old man from California was suspected of being a hacker and called himself, 'the Deceptive Duo'.
He faces several charges on hacking into government computers and defacing government websites.
In April 2002, the Deceptive Duo claimed to be a hacking group working to expose the lack of security within the US government's networks and other private-sector computer systems.
Click NEXT to read on . . .
Image: Deceptive Duo. Last updated on: September 28, 2011 09:28 IST

10. Michael Calce
Also known as MafiaBoy, Michael Calce, a high school student from West Island, Quebec launched a series of highly publicised denial-of-service attacks in February 2000 against large commercial websites including Yahoo!, Amazon.com, Dell, Inc, eBay, and CNN.
Image: Michael Calce.
The MySQL.com website has been struck by cybercriminals, who hacked their way in to serve up malicious code to visiting computers.
USA TODAYHackers cracked three companies that work with the most popular Web browsers to ensure the authenticity of Web pages where consumers type in sensitive information.The hacked firms are among more than 650 digital certificate authorities (CAs) worldwide that ensure that Web pages are the real deal when displayed by Microsoft's Internet Explorer, Firefox, Opera, Apple's Safari and Google's Chrome. A hacker gained access to digital certificate supplier DigiNotar this summer and began issuing forged certificates for dozens of marquee companies.Unable to cope with the fallout, the Dutch company filed for bankruptcy last week. Two other digital certificate companies, New Jersey-based Comodo and Japanese-owned GlobalSign, were similarly hacked this summer, exposing a glaring weakness in the Internet's underpinnings."The infrastructure baked into the Internet, which is based on trust, is starting to fall apart," says Michael Sutton, research vice president at security company Zscaler. CAs digitally certify account sign-ins, shopping and other pages where consumers type sensitive data. This sets up an encrypted connection to the Web browser, which displays the form for the consumer to fill out. The browser trusts only digitally signed pages.A counterfeiter issued valid DigiNotar certificates for 531 faked pages. Some of the pages were crafted to expertly impersonate online properties of Google, Microsoft, Skype, Equifax, Twitter, Facebook and the CIA, among others, according to consulting firm Fox-IT.This touched off a scramble to cut off the faked pages, which were difficult for consumers to spot as faked.The successful hacks demonstrated that it is possible to "impersonate any site on the Internet," says Josh Shaul, chief technical officer at security company AppSec.No banks or payment-service websites were targeted, says Mikko Hypponen, chief researcher at anti-virus company F-Secure. The hackers seem much more interested in harvesting personal data from e-mail services, social networks, credit bureaus, blogging sites and anonymity services. The pressure is on CAs and browser makers to do more to identify and quickly eradicate counterfeit certificates and faked Web pages, security experts say. "No one knows where the next breach will occur," says Jeff Hudson, CEO of digital certificate management company Venafi.Microsoft, maker of Internet Explorer, declined to comment, as did Apple, maker of the Safari browser. "The security of the Web is our collective responsibility," says Johnathan Nightingale, Mozilla's director of Firefox engineering.For more information about reprints & permissions, visit our FAQ's. To report corrections and clarifications, contact Standards Editor Brent Jones. For publication consideration in the newspaper, send comments to letters@usatoday.com. Include name, phone number, city and state for verification. To view our corrections, go to corrections.usatoday.com. 
When SSL was designed back in the mid-90s, the authenticity component was given the least thought and as Marlinspike put it, "with a bit of a hand wave."
The news wires are awash with stories about Facebook, cookies and privacy. The source of all this concern seems to be an article written by self-proclaimed "serial entrepreneur, writer and hacker" Nik Cubrilovic of Wollongong, New South Wales, Australia.
Cubrilovic has enjoyed dramatic media success with his concerns about Facebook cookies, but I think he's been barking up the wrong tree.
I might not know your identity, but I know it's the same person - or at least the same browser on the same PC - coming back for more. So I can target the content I serve based on your previous browsing history. It might not be you, but it very probably is.
On your first visit, Apple will set a browser cookie called s_vi, valid for five years, containing a random-looking string of hexadecimal digits. The value of this cookie is - at least as far as I can tell - unique to each brand-new visitor.





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**FILE** Syrian President Bashar Assad (Associated Press)
Who is hacking who? Smart phones can be used to hack other electronic devices without detectionDrive-by download attacks can come from mallicious emails or web pages An Android app can turn a smart phone into a hacking device within minutesPersonal information can then be a riskInformation security experts say many don't see smart phones as at risk
Computer hard drives, from closed criminal cases, sit on a shelf waiting to be wiped of information at the Department of Defense Cyber Crime Center in Linthicum, Thursday, Aug. 11, 2011. Hackers and hostile nations are launching increasingly sophisticated cyberattacks against U.S. defense contractors. And the Pentagon is extending a program to help protect its prime suppliers, while serving as a possible model for other government agencies. Pentagon analysts are investigating a growing number of cases involving the mishandling or removal of classified data from military and corporate systems. Defense officials say intrusions into defense networks are now close to 30 percent of the Pentagon's Cyber Crime Center's workload. (AP Photo/Cliff Owen) Close