Code Blue deemed bigger threat than Code Red

Chinese antivirus researchers have uncovered a modified variant of the Code Red worm, dubbed Code Blue, that has the potential to cause more damage to users of Microsoft Windows NT and Windows 2000 than earlier Code Red variants, according to a statement released Friday by Beijing-based software vendor Kingsoft Corp.

The company did not give an indication of just how many users have so far been affected by the worm. But like earlier variants of Code Red, Code Blue launches a denial of service attack. However, unlike other variants which launched a denial of service attack against the White House Web site, the Code Blue worm instead attacks an IP address (211.99.196.135) associated with the Web site of a Chinese network security provider, NSFocus Information Technology Co. Ltd.

At 12 p.m. ET, the NSFocus Web site and the targeted IP address were observed to be functioning normally.

Code Red was first discovered in mid-July, but made its biggest splash after infecting hundreds of thousands of computers worldwide in August.

Code Blue is deemed to be more threatening to users than earlier Code Red variants because, unlike Code Red, Code Blue gradually increases its usage of system resources and, if not stopped, can bring computers running Windows NT or Windows 2000 to a halt, the Kingsoft statement said. By comparison, computers affected by Code Red were largely able to continue functioning normally with no obvious degradation in system performance.

Earlier variants of the Code Red worm exploited a single buffer overflow vulnerability in versions of Windows NT and Windows 2000 running Internet Information Server (IIS). A buffer overflow vulnerability opens when space in a program's code that is reserved for transaction protocols is violated by a malicious program.

By comparison, Code Blue exploits multiple system vulnerabilities, including a Web server folder traversal vulnerability first announced by Microsoft late last year, the statement said. The Web server folder vulnerability in IIS is exploited by using a malformed URL address to access files and folders on a specific drive. This gives a malicious user control of a machine, including the ability to change or delete data and upload and run code on the server.

Information on the Web server folder traversal vulnerability and a patch can be found on Microsoft's Web site at http://www.microsoft.com/technet/treeview/default.asp?url=/technet/Security/Bulletin/ms00-078.asp. In addition, Kingsoft has developed a software tool that can detect and remove the Code Blue worm. It can be downloaded for free at http://www.iduba.net/download/other/tool_010907_CodeBlue.htm.

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