China's No. 1 Website has fallen victim to a group of hackers calling themselves the "Iranian Cyber Army," who replaced the site's home page with a political message.Baidu.com may not be well known outside of China, but as the country's leading search engine (far outranking Google), it receives a huge number of visits every day.

At approximately 10 a.m. Beijing time today, visitors to Baidu were greeted with a rather different home page than the one they are used to:

Defaced Baidu webpage

The defaced Web page declared that the site had been "hacked by the Iranian Cyber Army" in an attack that draws obvious parallels to the one that disrupted Twitter in December.

It appears that Baidu's Website was suspended for a while as its security team attempted to recover from the security breach. Although the site appears to have returned to normal operation, some Internet users at the time of this writing were still describing having difficulties getting through to it.

My guess is that Baidu's Web servers weren't actually hacked themselves, but instead its DNS records were compromised. This was how Twitter was struck by the Iranian Cyber Army last month.

DNS records work like a telephone book, converting human-readable Website names, like baidu.com, into a sequence of numbers understandable by the Internet. What seems to have happened is that someone changed the lookup, so when Chinese surfers entered baidu.com into their browsers they were instead taken to a Website that wasn't under the search engine's control.

Just imagine what could have occurred if they had pointed people to a malicious Website hosting malware rather than a political message.

Of course, mystery continues to surround the key question: Just who is the Iranian Cyber Army, and what is its motivation behind these Website attacks?

Graham Cluley is senior technology consultant at Sophos, and has been working in the computer security field since the early 1990s. When he's not updating his award-winning blog on the Sophos website, you can find him on Twitter at @gcluley. Special to Dark Reading.