Some individual appears to have hijacked more than a 1,000 home computers starting in late June or early July and has been installing a new Trojan Horse program on them. The Trojan allows this person to run a number of small websites on the hijacked home computers. These websites consists of only a few web pages and apparently produce income by directing sign-ups to for-pay porn websites through affiliate programs. Spam emails messages get visitors to come to the small websites.
To make it more difficult for these websites to be shut down, a single home computer is used for only 10 minutes to host a site. After 10 minutes, the IP address of the website is changed to a different home computer. The hacker is able to do this quick switching because he has installed DNS name servers for his domains on other home computers under his control. The DNS name servers specify that a hostname-to-IP-address mapping should only live for 10 minutes. Over the July 4th long weekend, some of these same web servers were used in an apparent phishing scam to collect stolen PayPal passwords and credit card numbers. Silicon.com has an article about this scam.
Joe Stewart of LURHQ has obtained a copy of the Trojan, which he has named Migmaf. His analysis of the Trojan was just released on LURHQ website.
The initial theory was that the Trojan was installing a mini-web server on hacked computer to host the porn websites. However, Joe's analysis shows that the Trojan is actually a reverse HTTP proxy that makes a home computer act as a front for a home base Web server.
Some of the domain names used by the websites of the Trojan are:
I've been monitoring these domains since July 5th and found over 2,000 unique IP address used by hosts in these domains. Almost all of these IP addresses are for commercial ISPs used by home computer users. AOL.com was the most used ISP.
One interesting feature of the Trojan is that it times the connection speed of a home computer that it is running on and reports the connection speed back to home base. The home base computer seems to only select a computer to run a reverse proxy server or the DNS name server if the computer has a high-speed cable or DSL Internet connection!
It is not known at the present time how the Trojan gets installed on people's computers. My theory is that the Sobig.e virus might be involved, but the evidence is not strong at the moment.
By Richard M. Smith, Computer & Internet Security Expert
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