A new Trojan horse program appeared on the Internet Friday, and security experts are worried that its disguise will help it infect a large number of computers rather quickly.
Known variously as Xombe and Downloader, the program is attached to an e-mail that purports to come from Microsoft Corp. and supposedly delivers security updates to the user"s computer. Experts haven"t yet analyzed all of the Trojan"s capabilities, but once activated, it downloads another executable file from a remote Web site. This file also appears to be a Trojan, which downloads and installs a third program. The third file can vary in name, but immediately begins requesting pages repeatedly from a Web site with a Russian domain, possibly as a denial-of-service attack.
Xombe arrives in an e-mail from the address windowsupdate@microsoft.com with a subject line of "Windows XP Service Pack 1 (Express)-Critical Update." The attachment is named "winxp_sp1.exe." According to an analysis of the program done by Computer Associates International Inc., the body of the message reads: