The sophisticated mass infection that's injecting attack code into hundreds of thousands of reputable web pages is growing and even infiltrated the website of the Department of Homeland Security.
While so-called SQL injections are nothing new, this latest attack, which we we reported earlier, is notable for its ability to infect huge numbers of pages using only a single string of text. At time of writing, Google searches here, here and here showed almost 520,000 pages containing the infection string, though the exact number changes almost constantly.
Other hacked sites include those belonging to the United Nations and the UK Civil Service.
The attack causes infected sites to redirect visitors to destinations that attempt to install malware on vulnerable machines. At time of writing, the malicious payloads attacked vulnerabilities that already have been patched. And in any case all three of the redirection sites were down, possibly because they were unable to handle the demand. But should the attackers get their hands on a newer exploit - say, one targeting a zero-day vulnerability in QuickTime - it would be relatively easy for them to swap out the payload.
One reason the infection has spread so widely is the attackers have managed to find a single attack string that seems to work on tens of thousands of different sites. Most web applications are custom -built for a particular site, so attackers likewise have to custom design attack parameters to exploit weakness. Not so here.
"These guys look like they've found a methodology to get a successful SQL injection generically across [many] websites," said Jeremiah Grossman, CTO of WhiteHat Security, which helps companies secure web applications. "That right there is like a skeleton key."
While the number of pages that have been infected is high, not all are able to launch an attack once a user visits them, according to Roger Thompson, chief research officer of anti-virus provider AVG.
"Very often they're on a page but the stuff doesn't actually fire when you get there," he said. "This is not a cunning, premeditated task; it's just a blast. They're just planting the stuff where they can and the result is a lot of pages [that] don't do anything."
But webmasters should not be complacent about removing the injected code from their sites and fixing buggy web apps to make sure more don't spring up.
"It's the cleanup effort that's just going to be monstrous," said Grossman, who said affected companies will have to either remove each overwritten table record one at a time, or revert to a recent backup. "Either way, it's going to take forever."