Stuxnet Malware Still Exploiting Microsoft Windows Security Hole

The Stuxnet malware targeting a Microsoft Windows vulnerability is continuing to spread in what some say is a targeted attack against industry. Here are some things your organization can do.

News of a Microsoft Windows zero-day vulnerability may have put the Stuxnet malware on the public's radar, but it has not stopped the malware's purveyors from trucking along.

As of this morning, Microsoft said it detected nearly 10,000 unique machines where Stuxnet infections were prevented.

The target of the malware is not ordinary users, but industrial companies using Siemens' SCADA (supervisory control and data acquisition) software. Its appearance has given rise to concerns about targeted attacks against the critical infrastructure, particularly since many of the infections are being reported in the United States. According to figures released July 19 by ESET Virus Lab, nearly 58 percent of all compromises are being reported in the United States. Another 30 percent were being reported in Iran, the vendor found.

"This worm is an exemplary case of a targeted attack exploiting a zero-day vulnerability...[and targeting] the industrial supervisory software SCADA," said Juraj Malcho, head of ESET's Virus Lab, in a statement. "In short - this is an example of malware-aided industrial espionage. The question is why the chart of affected nations looks as it does."

Once on systems, the malware looks to use default passwords to connect to the database associated with the SCADA systems to obtain files and run various queries to collect information, Symantec noted in an advisory. Still, Siemens has reportedly advised customers not to change their default passwords, arguing it "may impact plant operations."

According to Belarus-based security vendor VirusBlokAda, Stuxnet exploits a vulnerability in Windows Shell that can be triggered by browsing to the removable media drive using an application that displays shortcut icons. So far, security pros say it has been spreading primarily through infected USB devices, but can also be spread via other removable media as well.

While initial analysis found the drivers installed by the malware were digitally-signed by RealTek Semiconductor Corp., researchers at F-Secure said they found another driver digitally-signed by a company called JMicron Technology Corp. July 19.

Protecting against the malware can begin with implementing the workarounds disclosed by Microsoft to prevent exploitation of the Windows Shell vulnerability. According to Microsoft, users can follow the directions in the company's advisory and disable the displaying of icons for shortcuts, as well as the Windows WebClient service.

Meanwhile, security vendors have also updated their signatures to defend against the malware, though McAfee's Dmitri Alperovitch suggested anti-virus may not be the best solution.

"For protection of SCADA and other embedded systems, we do not recommend the traditional AV approach," said Alperovitch, vice president of threat research for McAfee Labs. "Instead, we have seen very successful use of whitelisting technologies...that can block all unknown or unidentified applications from running on a system."