Analyst's note:  Interesting .... you'll want to read the entire original article for additional insight. 

The Dimona complex in the Negev desert is famous as the heavily guarded heart of Israel’s never-acknowledged nuclear arms program, where neat rows of factories make atomic fuel for the arsenal.

Over the past two years, according to intelligence and military experts familiar with its operations, Dimona has taken on a new, equally secret role — as a critical testing ground in a joint American and Israeli effort to undermine Iran’s efforts to make a bomb of its own.

Behind Dimona’s barbed wire, the experts say, [....] Dimona tested the effectiveness of the Stuxnet computer worm, a destructive program that appears to have wiped out roughly a fifth of Iran’s nuclear centrifuges and helped delay, though not destroy, Tehran’s ability to make its first nuclear arms.

[....] Though American and Israeli officials refuse to talk publicly about what goes on at Dimona, the operations there, as well as related efforts in the United States, are among the newest and strongest clues suggesting that the virus was designed as an American-Israeli project to sabotage the Iranian program.

[....] The biggest single factor in putting time on the nuclear clock appears to be Stuxnet, the most sophisticated cyberweapon ever deployed.

In interviews over the past three months in the United States and Europe, experts who have picked apart the computer worm describe it as far more complex — and ingenious — than anything they had imagined when it began circulating around the world, unexplained, in mid-2009.

Many mysteries remain, chief among them, exactly who constructed a computer worm that appears to have several authors on several continents. But the digital trail is littered with intriguing bits of evidence.

In early 2008 the German company Siemens cooperated with one of the United States’ premier national laboratories, in Idaho, to identify the vulnerabilities of computer controllers that the company sells to operate industrial machinery around the world — and that American intelligence agencies have identified as key equipment in Iran’s enrichment facilities.

[....] The worm itself now appears to have included two major components. One was designed to send Iran’s nuclear centrifuges spinning wildly out of control. Another seems right out of the movies: The computer program also secretly recorded what normal operations at the nuclear plant looked like, then played those readings back to plant operators, like a pre-recorded security tape in a bank heist, so that it would appear that everything was operating normally while the centrifuges were actually tearing themselves apart.

The attacks were not fully successful: Some parts of Iran’s operations ground to a halt, while others survived, according to the reports of international nuclear inspectors. Nor is it clear the attacks are over: Some experts who have examined the code believe it contains the seeds for yet more versions and assaults.

“It’s like a playbook,” said Ralph Langner, an independent computer security expert in Hamburg, Germany, who was among the first to decode Stuxnet. “Anyone who looks at it carefully can build something like it.” Mr. Langner is among the experts who expressed fear that the attack had legitimized a new form of industrial warfare, one to which the United States is also highly vulnerable.

Officially, neither American nor Israeli officials will even utter the name of the malicious computer program, much less describe any role in designing it.

[....] By the accounts of a number of computer scientists, nuclear enrichment experts and former officials, the covert race to create Stuxnet was a joint project between the Americans and the Israelis, with some help, knowing or unknowing, from the Germans and the British.

The project’s political origins can be found in the last months of the Bush administration. In January 2009, The New York Times reported that Mr. Bush authorized a covert program to undermine the electrical and computer systems around Natanz, Iran’s major enrichment center. President Obama, first briefed on the program even before taking office, sped it up, according to officials familiar with the administration’s Iran strategy. So did the Israelis, other officials said. Israel has long been seeking a way to cripple Iran’s capability without triggering the opprobrium, or the war, that might follow an overt military strike of the kind they conducted against nuclear facilities in Iraq in 1981 and Syria in 2007.

Two years ago, when Israel still thought its only solution was a military one and approached Mr. Bush for the bunker-busting bombs and other equipment it believed it would need for an air attack, its officials told the White House that such a strike would set back Iran’s programs by roughly three years. Its request was turned down.

Now, Mr. Dagan’s statement suggests that Israel believes it has gained at least that much time, without mounting an attack. So does the Obama administration.

For years, Washington’s approach to Tehran’s program has been one of attempting “to put time on the clock,” a senior administration official said, even while refusing to discuss Stuxnet. “And now, we have a bit more.”

Finding Weaknesses

[....] Years before the worm hit Iran, Washington had become deeply worried about the vulnerability of the millions of computers that run everything in the United States from bank transactions to the power grid.

Computers known as controllers run all kinds of industrial machinery. By early 2008, the Department of Homeland Security had teamed up with the Idaho National Laboratory to study a widely used Siemens controller known as P.C.S.-7, for Process Control System 7. Its complex software, called Step 7, can run whole symphonies of industrial instruments, sensors and machines.

The vulnerability of the controller to cyberattack was an open secret. In July 2008, the Idaho lab and Siemens teamed up on a PowerPoint presentation on the controller’s vulnerabilities that was made to a conference in Chicago at Navy Pier, a top tourist attraction.

“Goal is for attacker to gain control,” the July paper said in describing the many kinds of maneuvers that could exploit system holes. The paper was 62 pages long, including pictures of the controllers as they were examined and tested in Idaho.

In a statement on Friday, the Idaho National Laboratory confirmed that it formed a partnership with Siemens but said it was one of many with manufacturers to identify cybervulnerabilities. It argued that the report did not detail specific flaws that attackers could exploit. But it also said it could not comment on the laboratory’s classified missions, leaving unanswered the question of whether it passed what it learned about the Siemens systems to other parts of the nation’s intelligence apparatus.

The presentation at the Chicago conference, which recently disappeared from a Siemens Web site, never discussed specific places where the machines were used.

But Washington knew. The controllers were critical to operations at Natanz, a sprawling enrichment site in the desert. “If you look for the weak links in the system,” said one former American official, “this one jumps out.”

[....] the worm only kicked into gear when it detected the presence of a specific configuration of controllers, running a set of processes that appear to exist only in a centrifuge plant. “The attackers took great care to make sure that only their designated targets were hit,” he said. “It was a marksman’s job.”

For example, one small section of the code appears designed to send commands to 984 machines linked together.

Curiously, when international inspectors visited Natanz in late 2009, they found that the Iranians had taken out of service a total of exactly 984 machines that had been running the previous summer.

But as Mr. Langner kept peeling back the layers, he found more — what he calls the “dual warhead.” One part of the program is designed to lie dormant for long periods, then speed up the machines so that the spinning rotors in the centrifuges wobble and then destroy themselves. Another part, called a “man in the middle” in the computer world, sends out those false sensor signals to make the system believe everything is running smoothly. That prevents a safety system from kicking in, which would shut down the plant before it could self-destruct.

“Code analysis makes it clear that Stuxnet is not about sending a message or proving a concept,” Mr. Langner later wrote. “It is about destroying its targets with utmost determination in military style.”

This was not the work of hackers, he quickly concluded. It had to be the work of someone who knew his way around the specific quirks of the Siemens controllers and had an intimate understanding of exactly how the Iranians had designed their enrichment operations.

[....] Stuxnet is not the only blow to Iran. Sanctions have hurt its effort to build more advanced (and less temperamental) centrifuges. And last January, and again in November, two scientists who were believed to be central to the nuclear program were killed in Tehran.

The man widely believed to be responsible for much of Iran’s program, Mohsen Fakrizadeh, a college professor, has been hidden away by the Iranians, who know he is high on the target list.

Publicly, Israeli officials make no explicit ties between Stuxnet and Iran’s problems. But in recent weeks, they have given revised and surprisingly upbeat assessments of Tehran’s nuclear status.[....]"