MS issues warning on Web attacks, pushes XP SP2 beta

Microsoft Corp. acknowledged Thursday that Internet Information Server (IIS), a component of the Windows 2000 Server, and holes in the Internet Explorer Web browser are being used in widespread attacks that are compromising Web pages and using them as launching pads for malicious computer code.

Microsoft issued an alert late Thursday and posted a Web page with information on the attacks. The company urged customers to apply the latest security patches for both IIS and the Internet Explorer Web browser and increase the security settings on Internet Explorer browser. In an unusual move, Microsoft noted that users that are running its as-yet-unreleased Windows XP Service Pack 2 operating system are protected. (See: http://www.microsoft.com/security/incident/settings.mspx.)

The warnings from the Redmond, Washington, company came as antivirus and computer security experts said Friday that an organized gang of Russian hackers were behind the attacks and were using the security holes in a coordinated, global attack to steal sensitive personal and financial information from customers of leading banking and e-commerce Web sites.

Rumors of the attacks surfaced Thursday, after network administrators spotted malicious files on Windows 2000 machines running IIS Version 5. Computer security experts are still analyzing the attacks, but have isolated files involved in the attack and how the malicious files are being spread from Web sites to customer machines, according to a message posted on The SANS Institute's Internet Storm Center.

The infected files have names such as Download_Ject_Symantec.doc, ipaddress.txt, issue.csv, ads.vbs and agent.exe. They are placed in a Windows folder named "inetsrv." In addition, the configuration of IIS is changed, so that an option called "enable document footer," is turned on, according to the Internet Storm Center.

That Microsoft Web site encourages network administrators to apply a recent patch for IIS, MS04-011. Systems that did not have this patch may be vulnerable to the attacks, the company said. A previously unknown and unpatched (or "zero day") security vulnerability in IIS may also be to blame for the infections, said Ken Dunham, director of malicious code at iDefense Inc.

The IIS vulnerability allows the attackers to place malicious files on the Windows 2000 machines and change a configuration setting called the "enable document footer" feature, which is used to append files, such as copyright statements or disclaimers, to the bottom of Web pages served by IIS. In the case of the latest attack, the malicious JavaScript files are appended as "footers" to every file on the Web site, Dunham said.

When Web surfers visit the site, the malicious JavaScript code is sent to the user's client machine, along with other Web site files, and run. For people visiting those sites, a combination of holes in Internet Explorer, one that has been patched by Microsoft and one that has not, is allowing malicious programs to be surreptitiously placed on customers' machines, Dunham said. The code redirects the user's Web browser to a Russian Web site from which a Trojan horse program is unknowingly downloaded and installed on the user's system, according to Johannes Ullrich, chief technology officer at the Internet Storm Center.

That program contains a key-capture feature that can be used to steal password and credit card information from Web sessions, and forward those to the criminals behind the scam, experts said.