Microsoft attack worm rides on the back of MyDoom
The latest version of the MyDoom could be just the first stage of a two-stage attack targeting Microsoft's main website.
MyDoom-M (AKA MyDoom-O) is a mass-mailing worm that opens a back door - Zincite-A - on port 1034/TCP of compromised PCs. This gives attackers remote, unauthorised access to infected PCs. First spotted on Monday afternoon, MyDoom-M has spread like wildfire, causing availability problems for leading search engines because of its use of sites such as Google to hunt for email addresses to attack.
Finnish anti-virus firm F-Secure is reporting the spread of a new worm, Zindos, which works together with MyDoom. Zindos-A is now hitching a ride on the back of the MyDoom, using the infected machine lists and the backdoors prepared by MyDoom-M, to spread. Zindos's payload includes a denial of service attack on www.microsoft.com. Once Zindos has infected a machine it causes the machine to request the http://www.microsoft.com/ domain in an infinite loop, with 50ms delays. This behaviour could help to explain the difficulties some Reg experienced visiting the software giant's website earlier this week.
The first version of MyDoom, which appeared on the scene in January, targeted SCO's web presence. Virus writers have already used the backdoor created by worms in the MyDoom series to spread their wares, so the tactics used by the Zindos worm shouldn't come as too much of a surprise.
Based on similarities in coding style, F-Secure reckons that the same virus writer created both MyDoom-M and Zindos. F-Secure has a produced a free MyDoom disinfection tool here. ®