The Twitter micro-blogging and social networking service was hit with a denial-of-service attack Thursday morning that has rendered the site unavailable for users.

Governments looking to silence critics and stymie opposition have added DDOS (distributed denial of service) attacks to their censoring methods, according to a security expert speaking at the Source Boston Security Showcase.

A scrap between two pornographic Web sites turned nasty when one figured out how to take down the other by exploiting a previously unknown quirk in the Internet's Domain Name System (DNS).

Massive distributed denial-of-service attacks against ISPs and their customers doubled in intensity over the past year, according to a new survey.

Finding ways to limit DoS attacks and SMS spam by making it harder to spoof the origin of electronic communications is on the agenda at a telecommunications standards meeting this week -- but civil rights advocates worry it could put an end to anonymity on the Internet.

What Japan lacks in geographic size, it more than makes up for in Internet attack traffic.

Twitter and Facebook were hit today with denial-of-service attacks that can knock a site offline, but don't steal information or cause permanent damage. The question is, why?