A compromise that is moving virally across websites is making unwitting people who surf to them part of a botnet that redirects Google search results, a security researcher has warned.

During the past week, the number of websites identified as infected have almost tripled, according to researcher Mary Landesman with real-time malware scanning specialist ScanSafe tracking the attacks since March. Normally, web compromises die out after a few weeks, as search engines and anti-virus programs grow wise to them. But that's not happening this time.

"The growth rate is very unusual for this type of compromise, and the fact that it's escalating so quickly is what has us concerned," Landesman told The Reg.

The exploit code is unique for every website, making it impossible to identify a compromised site until someone has accidentally surfed there. It uses obfuscated Javascript that's burrowed deep into a website's source code to exploit unpatched vulnerabilities in a visitor's Adobe Flash and Reader programs. Victims then join a botnet that manipulates their Google search results.

The malware also sifts through a victim's computer in search of FTP credentials that can be used to infect still more websites with the malicious Javascript. The combination of its stealth and ability to find new websites is allowing the infection to grow virally, Landesman said.

The goal of the malware appears to be to siphon dollars away from Google's highly profitable advertising franchises. By injecting ads and links into certain searches, infected users see results that are different than they would otherwise be.

The longevity of the mass compromise speaks to the resourcefulness of the attackers. When they first set out, they dropped static attack code into PHP, HTML and other scripts of infected websites, but in time, website owners learned how to detect and remove the infection. The miscreants soon started a second wave of attacks that installed dynamically generated malware on infected sites as soon as the static script was removed.

The source of the latest Javascript is gumblar.cn, which has a Moscow IP address that reverses to ukservers.com. ScanSafe has more details here: http://blog.scansafe.com/journal/2009/5/8/google-serps-redirections-turn-to-bots.html and here http://blog.scansafe.com/journal/2009/5/14/gumblar-qa.html .

(The Register)