NewsApril 25, 2017 @ 6:31 AM

Stuxnet: The Computer Worm That Keeps on Living

In 2010, a new kind of computer worm was discovered. At the time, it took advantage of a then-unknown flaw in the Windows shell present in every supported version of Windows. This included Windows XP SP3, Server 2003 SP2, Vista SP1 and SP2, Server 2008 SP2 and R2, and Windows 7.

The flaw allowed local users or remote attackers to execute arbitrary code via a crafted .LNK or .PIF shortcut file. While shortcuts help users easily access information, they are often accessed as files within a LNK extension. They also present themselves as PIF files when attached to MS-DOS programs.

The first known malware using this attack method was Stuxnet, which leveraged CVE-2010-2772 in Siemens WinCC SCADA systems, a kind of controller used in uranium spin systems. But what does this have to do with today?

A Life Beyond the Patch

Though a vulnerability like this may get patched by the manufacturer, that doesn’t mean that the patch actually got installed on all affected machines. Kaspersky Lab found that in 2015 and 2016, Stuxnet was used to target about a quarter of Kaspersky users who had encountered an exploit. It’s still very much in the active column.

The firm addressed this longevity in its research, noting that it may be “due to the fact that malware that uses these exploits have a self-replicating feature, constantly recreating themselves in the attacked network where vulnerable computers are installed.” The clear message of the report is that an exploit’s life cycle doesn’t necessarily end with the release of a security patch, as Kaspersky noted on its blog, SecureList.

Researchers explained that approximately two-thirds of the vulnerabilities tracked were used by more than one threat actor. In other words, one threat actor picks up techniques from another. Kaspersky found that an exploit technique can be grabbed and repurposed by big attackers within hours.

Addressing the Continuing Computer Worm

Ultimately, the older the operating system, the more vulnerable it is. CSO Online observed that an older operating system such as Windows Server 2003 will “remain vulnerable indefinitely to some of the risks because Microsoft no longer supports the software.”

The obvious mitigation lesson from Stuxnet, among others, is to make sure all machines in a network are patched. The use of patch management solutions that allowed centralized software updates on all endpoints may improve vulnerability management and help industrial IT managers get their systems under control.

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Larry Loeb

Principal, PBC Enterprises

Larry Loeb has written for many of the last century's major "dead tree" computer magazines, having been, among other things, a consulting editor for BYTE magazine and senior editor for the launch of WebWeek. He wrote for IBM's DeveloperWorks site for seven years and has written a book on the Secure Electronic Transaction Internet protocol. His latest book has the commercially obligatory title of Hack Proofing XML. He's been online since uucp "bang" addressing (where the world existed relative to !decvax), serving as editor of the Macintosh Exchange on BIX and the VARBusiness Exchange.