A newly discovered piece of malicious code dubbed Duqu is closely related to the notorious Stuxnet worm that damaged Iran’s nuclear-enrichment centrifuges last year. Although it has no known target or author, it sets the stage for more industrial and cyberwar attacks, experts say.

“This is definitely a troubling development on a number of levels,” says Ronald Deibert, director of Citizen Lab, an Internet think-tank at the University of Toronto who leads research on cyberwarfare, censorship, and espionage. “In the context of the militarization of cyberspace, policymakers around the world should be concerned.”

Indeed, the spread of such code could be destabilizing. The Pentagon’s cyberwar strategy, for example, makes clear that computer attacks on industrial and civilian infrastructure like chemical factories or power grids as well as military networks could be regarded as equivalent to a conventional bombing or other attack, if civilians were endangered.

Duqu was described Tuesday by the security firm Symantec, which says the malware’s purpose appears to be gathering intelligence from computerized industrial control systems. It doesn’t do damage, but rather spies on them to gather information relevant to making future attacks.

Symantec researchers wrote that Duqu has circulated for 10 months and is “essentially the precursor to a future Stuxnet-like attack,” but with the target unknown. The code can monitor messages and processes, and look for information including the design of so-called SCADA systems (for “supervisory control and data acquisition”). These are computer systems that are used at industrial plants and power plants to control things like pumps, valves, and other machinery.

The code was originally discovered at a handful of unnamed sites in Europe by an undisclosed research team and given to Symantec for analysis on October 14, the company says.

The Stuxnet worm was highly specific to the Iran’s Natanz facility, where uranium enrichment is conducted in hardened underground bunkers. Iran maintains that Natanz is an entirely peaceful effort to make fuel for nuclear power plants, but some observers fear it may also serve as a bomb-making program.

Stuxnet went far beyond shutting down or disrupting operations. After infecting Seimens-made control systems, it sent out instructions that would damage delicate centrifuges, in which bomb- or reactor-grade uranium is separated from naturally occurring uranium. In a Hollywood touch, the worm also displayed normal information on computer screens so that human operators wouldn’t notice the attacks.

Stuxnet is widely regarded as the most sophisticated piece of malicious software ever created. Earlier this year, the New York Times reported that Stuxnet was tested by Israeli agents on centrifuges at an Israeli site, and pointed to this and other clues that Stuxnet may have been “designed as an American-Israeli project to sabotage the Iranian program.”

But much is not known. “We don’t know what it’s for. The initial speculation is that it was a precursor to the next Stuxnet, but we don’t know anything,” says Bruce Schneier, a cryptologist and security expert. “It is what it is. We don’t know.”

Duqu creates a kind of “back door” that can receive commands from, and deliver information to, a so-called command-and-control server somewhere in India. (That server is not known to have sent out instructions, Symantec says.) The company says the back door stays open for only 36 days, and then the malware deletes itself.

Symantec says its researchers—after sending out a detection tool following the discovery of the code in Europe—have found Duqu on industrial computers “around the globe.” Like Stuxnet, which infected thousands of computers in 155 countries last year, Duqu got aboard victim computers by means of a stolen digital certificate—a cryptographic code that authenticates a piece of software on a target machine. “On the whole, this underscores the critical importance of cyberspace security policy and practices, national, regionally, and internationally,” Deibert says.