Monday, September 21, 2009

Google Users Targeted By New Malicious Websites

eSoft’s Threat Prevention Team has been tracking compromised sites that host PageRank Bombs since 2008.  The attacker hacks a site, but instead of putting exploits on the hacked site, they put links to other websites in order to boost the search result ranking on various search engines.  Initially this was being used for ad sites, porn sites, and pharmafraud sites.  Now, however, it is being used to boost the results of malicious sites, but with a new twist that targets Google users.

The sites whose search engine ranking is being boosted are now serving up malware through a complex series of redirects.  However, the redirects and the malware are only served up if the user gets to the site after clicking the link on Google.  Going directly to the malicious site (by pasting into your browser directly) results in a harmless page.

For example, using Google, a search for “nhl all-time scoring leaders” returns several malicious results on the first page (in the 5th, 6th, 7th, 8th and 10th positions). 

Going to the website, hxxp://, directly results in an innocuous page like this:

[Note: during research by eSoft, this page did not return malicious content when directly viewed, but extreme caution should still be taken before visiting any websites listed in this post.]

However, clicking the link in the Google search results will bring the user to a web site using a common Rogue Anti-Virus template that alerts the user that their PC is infected and prompts unsuspecting users to download what is really a Trojan:

The Trojan being downloaded at this point has only a 7% detection rate by anti-virus software with Microsoft, NOD32 and Panda detecting.

Some of the sites being used include:

These redirect through some URLs including:

As far as eSoft’s TPT can tell, the referrer must have this string,, in it  and the User-Agent must indicate a Windows machine or the malware will not be delivered.  It does not appear that users of other search engines or operating systems are yet being targeted.

1 comment:

Lee Graves said...

For more information on this attack take a look at this post in the Internet Storm Center Diary. The .htaccess file and rewrite engine usage is described in more detail.

The resurgence of this technique comes in the wake of a large number of newly published exploits. Notable exploits include the IIS FTP exploit and Wordpress Admin Hacks as well as using Fake AV and the Zbot(Zeus) Trojan to capture FTP credentials.

The majority of the sites found in this report were compromised sites which likely used one of the techniques listed above. Once compromised fraudsters create links to Fake AV and employ PageRank bombs to increase their click counts.

Rogue AV hackers are constantly on the lookout for new servers to compromise to spread their malware. Be sure to keep your server software up to date, use strong credentials that are updated frequently and check the contents of your .htacess file.