Security watchers have discovered a string of malicious websites that install Trojan code, allowing hackers to compromise end-user banking credentials for more than 50 financial institutions and ecommerce websites.

Thousands of surfers a day are falling victim to the sophisticated attack, net security firm Websense warns.

The websites are hosted in Germany, England, and Estonia, and use a round robin DNS, resolving to five unique IP addresses that change on each occasion. Each site hosts the same code, exploiting the MS06-014 vulnerability in a bid to install a Trojan downloader without end-user interaction.

When surfers visit the sites, they are directed to one of the five servers which covertly downloads a file called “iexplorer.exe” onto vulnerable PCs. Meanwhile, users are informed that the site is temporarily busy. Hackers cheekily suggest that surfers might want to shut down any firewall and anti-virus software they have running.

If successfully downloaded, the “iexplorer.exe” file attempts to download additional malware components from a server in Russia that also acts as a bot controller, giving hackers access to compromised machines. The bot controller also has a database query interface that gives the attacker a simple search interface for additional information.

Source: The Register