The attacks began on Wednesday, when hackers hit the FBI's Web site. While the Senate site was back online by Sunday, the FBI site remained out of service over the holiday weekend. On Friday, hackers temporarily defaced the State of Virginia's Web site. While exact numbers are hard to come by because most organizations don't report minor intrusions to law-enforcement authorities, hacker attacks are on the rise. Breaking into networks is also increasing because corporations and government agencies have more entry points.
Hackers often break into networks simply to prove that they can.
Like climbers on Mount Everest, they almost always plant a flag, something to remind others they were there.