Hackers with political agenda bring down Twitter

Twitter users got an upleasant surprise early Friday morning when attempts to log in to the microblogging site instead redirected them to a cryptic anti-American message from a group calling itself the Iranian Cyber Army.

Twitter.com was briefly taken offline and, later in the morning, the official Twitter blog posted updates regarding the incident.

It’s not clear who exactly is behind the attacks. According to a Wall Street Journal report, Iran is using social media to intimidate and harass Iranians worldwide by tracking activity on Twitter, Facebook and similar sites, identifying and contacting those viewed as dissidents.

Twitter said in a blog post that the attack was targeted at the site’s Domain Name System, which redirected users to the defaced page. The site is now functional and Twitter said it is investigating the incident.

Meanwhile, TechCrunch is advising that those using their Twitter password on other accounts change passwords.

The incident is not the first between Iran and the popular microblog. Last June amid the contested re-election of Iranian president Mahmoud Ahmadinejad, protesters used Twitter to communicate among themselves and with the rest of the world when the Iranian government imposed a news blackout in Tehran.

The State Department reportedly asked Twitter not to take the site off line for scheduled maintenance in order to allow continued tweeting from inside the crisis zone.