USAToday.com is among over a million websites that have fallen victim by a mounting Web attack (not pictured; photo shows a 2002 hack, see below for more details). Other high profile sites impacted by the attack include Target.com and Walmart.com. 

The hacking activity, which was first reported in mid-March by security researcher Dancho Danchev, has broadened in scope, increasing both in "number and importance of the [affected] sites," Danchev said.

The attackers have not hacked into servers, but are instead targeting sites' search functions. When a user searches a popular term on a website's internal search function, the hacker tacks on an HTML command at the end of the search. That code then redirects the user to a malicious site where his computer is at risk for spyware and Trojan horses.

What stands to perpetuate the Web attack is sites' search cache. According to InfoWorld, sites often submit a saved copy of their search results to Google in order to boost their ranking. When someone searches that term in Google, the tainted cache results then appear, making it more likely that the malicious HTML code will spread.

Danchev said that websites could guard against the problem by "doing a better job of checking the search queries on their internal search engines to make sure there is no malicious code."

USA Today also had troubles with hackers back in 2002; click on the photo to see an incomplete screen shot that was taken of the hacker-modified homepage before the paper pulled their server. And USA Today is not alone; the website of the UK-based Telegraph shut down for a day in May 2007 after being hit by hackers.

Source: InfoWorld through I Want Media, Horked.net through Ask Bjorn Hansen