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.
Compromised machines automatically connect to the server in Russia, and not legitimate ecommerce firms, when users log-on in an attempt to carry out an ecommerce transaction, security firm Websense reports. It warns thousands of surfers have already been hit by the attack, based on statistics held on the attack server.
"Once the DLLs are installed and loaded and the end-user connects to one of more than 50 financial institutions or ecommerce websites, the code transparently replaces some HTML within the page and posts the end-user's logon credentials to the server in Russia.
"At the time of this alert, the statistics showed more than 1,000 successful infections per day, with the USA and Australia leading the list," Websense explains. ®