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Google Image Poisoning. What’s New in June?

29 Jun 11   Filed in Website exploits with 3 Comments

This is the second (more techie) part in the series of posts about a new wave of the Google Image poisoning attack. This part will heavily refer to the detailed description of the attack that I made back in May. Most of the aspects are still true so I will only talk about changes here. If you want to have a complete picture, I suggest that you read the original description first.

Changed doorway behavior

After May 18th, I noticed that doorway pages no longer redirected me anywhere when I clicked on poisoned search results. Neither to bad sites nor to home pages of compromised sites. Instead they displayed the spammy content generated for search engine crawlers only.

That was strange. That could never happen if the old algorithm was still in use.

Then I checked the cache directories (./.log/compromiseddomain.com/) and found new maintenance files there: don.txt and xml.txt. The don.txt file contained HTML template of spammy pages and was a replacement for the shab100500.txt file used by the original algorithm. The xml.txt contained the following string: bG92ZS1ibG9nY29tLm5ldA==, which decoded (base64) to “love-blogcom.net“. It was clear it was a more secure replacement for xmlrpc.txt that stored the domain name of a remote malicious server in plain text.

A few days later, the xml.txt files was replaced by xml.cgi, which was a clever step since .cgi files produce server errors when you try to open them in directories that aren’t configured to execute CGI scripts.

So I knew that the doorway script was updated, but I couldn’t understand why the doorways exhibited no malicious behavior when I clicked on hijacked image search results. That didn’t make much sense. What was the purpose of showing those spammy unintelligible pages without trying to monetize the traffic? The only plausible idea was they were playing the “long game” and needed some time to have the new pages rank well without risks of being identified as cloaked or malicious content, and when many pages reach prominent positions in search results they’ll start redirect web searchers to bad sites. Well, that was a working hypothesis until I got the source code of the new doorway script. The reality is crooks don’t want to play “long games” if they can monetize right away – the new doorway pages did redirect to bad site but my virtual environment wasn’t properly configured to trigger the redirects.
Continue – Dissecting the updated Google Image poisoning attack »»