Microsoft has pushed out an update that prevents Windows being used as a launching pad for malicious code.
The software update makes changes to the configuration of Windows 2000, XP and Windows Server 2003 to help fight off attacks, detected last week, that use Web pages running Internet Information Server (IIS) to run code on people's machines.
It disables a Windows component called ADODB.Stream, which online criminals were using to copy malicious code onto Windows users' machines, according to Stephen Toulouse, security program manager in Microsoft's Security Response Center. The company is also planning a number of software patches, including a patch for a gaping Internet Explorer security hole in coming weeks, and may release those outside of its monthly security patch schedule, he said.
Microsoft released the update one week after reports surfaced of website attacks by a Russian criminal hacking group called the Hangup Team. Some companies that failed to apply a recent software patch for Microsoft's IIS Version 5.0 Web server fell victim to the attacks, in which hackers modified the configuration of IIS servers, allowing malicious code to be appended to every HTML document served from the Web page.
Two vulnerabilities in Windows and Explorer enabled attackers to silently run the malicious code on machines that visited the compromised sites, redirecting the customers to now-dormant websites controlled by the hackers from which a Trojan horse program is unknowingly downloaded and installed on the user's system and used to capture sensitive information, such as account numbers, user names and passwords.
The ADODB.Stream component that Microsoft disabled helped the hackers to place that Trojan program on victim computers, Toulouse said. The ActiveX program was "legitimate functionality" of Internet Explorer that was designed to allow Windows customers to read and write files, including non-text "binary" files to a hard drive using a Web page interface. Microsoft does not believe that it is a widely-used feature, however, and moved to disable it when it learned that hackers were using it to deliver malicious code, he said.
For companies with applications that do use the ADODB.Steam component, Microsoft posted an article on its Knowledge Base explaining how to modify the Windows registry to disable or enable ADODB.Stream, and how disabling the component might affect Web applications that use the component, which Microsoft said could be "any line-of-business Web application that requires a file to be loaded or to be saved to the hard disk."
Microsoft is testing software patches to address other vulnerabilities exploited by the Hangup Team, including the unpatched "cross zone scripting" vulnerability, which allows attackers to trick Explorer into loading insecure content using relaxed security precautions typically applied to files stored on the local hard drive or obtained from a trusted Web site such as www.microsoft.com.
The next version of Windows XP, Service Pack 2, will also protect against the Web attacks, even though it will not contain the new change that deactivates ADODB.Stream, Toulouse said.
Customers are advised to visit the Windows update website to download the ADODB.Stream change, or use the automatic update feature in Windows to obtain it.