Gary McKinnon, a 41-year-old British hacker, was arrested and released in 2002 when the US Metropolitan Police found evidence about several hack attempts over secret information stored by the authorities. According to Viruslist, the hacker caused almost $700.000 worth of damages after he managed to connect to several classified networks and view secret information stored on the computers. The hacker decided to appeal the court's order that sends him to prison for almost 45 years, requiring his extradition to UK.

"41-year-old McKinnon was originally arrested and then released by the Metropolitan Police in 2002, but the US authorities, which lodged an extradition request, then pursued his case. Despite those claims, and his own admission of being a "bumbling computer nerd", the US authorities maintain Mr McKinnon caused some $700,000 worth of damages and rendered key defense computer networks inoperable," the same publication reported.

The interesting aspect of the case is the hacker's opinion that sustained he is now guilty because the US military systems have weak passwords and extremely vulnerable firewalls. Gary McKinnon added he was only looking for evidence about the existence of the UFOs and he managed to connect to the computers using a blank password.

This is not the first time when the hackers manage to connect to private networks and view secret information, although the computers are owned by powerful organizations. Although there are numerous techniques to protect a system, a recent study revealed that hackers are more and more powerful, most of them trying to guess the password using the common words: admin, password, root or default. That's why all the security companies from the entire world recommend clients to use strong passwords containing both letters and numbers.