Entries Tagged "terrorism"

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Data Mining for Terrorists

In the post 9/11 world, there’s much focus on connecting the dots. Many believe that data mining is the crystal ball that will enable us to uncover future terrorist plots. But even in the most wildly optimistic projections, data mining isn’t tenable for that purpose. We’re not trading privacy for security; we’re giving up privacy and getting no security in return.

Most people first learned about data mining in November 2002, when news broke about a massive government data mining program called Total Information Awareness. The basic idea was as audacious as it was repellent: suck up as much data as possible about everyone, sift through it with massive computers, and investigate patterns that might indicate terrorist plots. Americans across the political spectrum denounced the program, and in September 2003, Congress eliminated its funding and closed its offices.

But TIA didn’t die. According to The National Journal, it just changed its name and moved inside the Defense Department.

This shouldn’t be a surprise. In May 2004, the General Accounting Office published a report that listed 122 different federal government data mining programs that used people’s personal information. This list didn’t include classified programs, like the NSA’s eavesdropping effort, or state-run programs like MATRIX.

The promise of data mining is compelling, and convinces many. But it’s wrong. We’re not going to find terrorist plots through systems like this, and we’re going to waste valuable resources chasing down false alarms. To understand why, we have to look at the economics of the system.

Security is always a trade-off, and for a system to be worthwhile, the advantages have to be greater than the disadvantages. A national security data mining program is going to find some percentage of real attacks, and some percentage of false alarms. If the benefits of finding and stopping those attacks outweigh the cost—in money, liberties, etc.—then the system is a good one. If not, then you’d be better off spending that cost elsewhere.

Data mining works best when there’s a well-defined profile you’re searching for, a reasonable number of attacks per year, and a low cost of false alarms. Credit card fraud is one of data mining’s success stories: all credit card companies data mine their transaction databases, looking for spending patterns that indicate a stolen card. Many credit card thieves share a pattern—purchase expensive luxury goods, purchase things that can be easily fenced, etc.—and data mining systems can minimize the losses in many cases by shutting down the card. In addition, the cost of false alarms is only a phone call to the cardholder asking him to verify a couple of purchases. The cardholders don’t even resent these phone calls—as long as they’re infrequent—so the cost is just a few minutes of operator time.

Terrorist plots are different. There is no well-defined profile, and attacks are very rare. Taken together, these facts mean that data mining systems won’t uncover any terrorist plots until they are very accurate, and that even very accurate systems will be so flooded with false alarms that they will be useless.

All data mining systems fail in two different ways: false positives and false negatives. A false positive is when the system identifies a terrorist plot that really isn’t one. A false negative is when the system misses an actual terrorist plot. Depending on how you “tune” your detection algorithms, you can err on one side or the other: you can increase the number of false positives to ensure that you are less likely to miss an actual terrorist plot, or you can reduce the number of false positives at the expense of missing terrorist plots.

To reduce both those numbers, you need a well-defined profile. And that’s a problem when it comes to terrorism. In hindsight, it was really easy to connect the 9/11 dots and point to the warning signs, but it’s much harder before the fact. Certainly, there are common warning signs that many terrorist plots share, but each is unique, as well. The better you can define what you’re looking for, the better your results will be. Data mining for terrorist plots is going to be sloppy, and it’s going to be hard to find anything useful.

Data mining is like searching for a needle in a haystack. There are 900 million credit cards in circulation in the United States. According to the FTC September 2003 Identity Theft Survey Report, about 1% (10 million) cards are stolen and fraudulently used each year. Terrorism is different. There are trillions of connections between people and events—things that the data mining system will have to “look at”—and very few plots. This rarity makes even accurate identification systems useless.

Let’s look at some numbers. We’ll be optimistic. We’ll assume the system has a 1 in 100 false positive rate (99% accurate), and a 1 in 1,000 false negative rate (99.9% accurate).

Assume one trillion possible indicators to sift through: that’s about ten events—e-mails, phone calls, purchases, web surfings, whatever—per person in the U.S. per day. Also assume that 10 of them are actually terrorists plotting.

This unrealistically-accurate system will generate one billion false alarms for every real terrorist plot it uncovers. Every day of every year, the police will have to investigate 27 million potential plots in order to find the one real terrorist plot per month. Raise that false-positive accuracy to an absurd 99.9999% and you’re still chasing 2,750 false alarms per day—but that will inevitably raise your false negatives, and you’re going to miss some of those ten real plots.

This isn’t anything new. In statistics, it’s called the “base rate fallacy,” and it applies in other domains as well. For example, even highly accurate medical tests are useless as diagnostic tools if the incidence of the disease is rare in the general population. Terrorist attacks are also rare, any “test” is going to result in an endless stream of false alarms.

This is exactly the sort of thing we saw with the NSA’s eavesdropping program: the New York Times reported that the computers spat out thousands of tips per month. Every one of them turned out to be a false alarm.

And the cost was enormous: not just the cost of the FBI agents running around chasing dead-end leads instead of doing things that might actually make us safer, but also the cost in civil liberties. The fundamental freedoms that make our country the envy of the world are valuable, and not something that we should throw away lightly.

Data mining can work. It helps Visa keep the costs of fraud down, just as it helps Amazon.com show me books that I might want to buy, and Google show me advertising I’m more likely to be interested in. But these are all instances where the cost of false positives is low—a phone call from a Visa operator, or an uninteresting ad—and in systems that have value even if there is a high number of false negatives.

Finding terrorism plots is not a problem that lends itself to data mining. It’s a needle-in-a-haystack problem, and throwing more hay on the pile doesn’t make that problem any easier. We’d be far better off putting people in charge of investigating potential plots and letting them direct the computers, instead of putting the computers in charge and letting them decide who should be investigated.

This essay originally appeared on Wired.com.

Posted on March 9, 2006 at 7:44 AM • View Comments

Fighting Misuse of the Patriot Act

I like this idea:

I had to sign a tedious business contract the other day. They wanted my corporation number—fair enough—plus my Social Security number—well, if you insist—and also my driver’s license number—hang on, what’s the deal with that?

Well, we e-mailed over a query and they e-mailed back that it was a requirement of the Patriot Act. So we asked where exactly in the Patriot Act could this particular requirement be found and, after a bit of a delay, we got an answer.

And on discovering that there was no mention of driver’s licenses in that particular subsection, I wrote back that we have a policy of reporting all erroneous invocations of the Patriot Act to the Department of Homeland Security on the grounds that such invocations weaken the rationale for the act, and thereby undermine public support for genuine anti-terrorism measures and thus constitute a threat to America’s national security.

And about 10 minutes after that the guy sent back an e-mail saying he didn’t need the driver’s license number after all.

Posted on March 8, 2006 at 7:17 AM • View Comments

The Terrorist Threat of Paying Your Credit Card Balance

This article shows how badly terrorist profiling can go wrong:

They paid down some debt. The balance on their JCPenney Platinum MasterCard had gotten to an unhealthy level. So they sent in a large payment, a check for $6,522.

And an alarm went off. A red flag went up. The Soehnges’ behavior was found questionable.

And all they did was pay down their debt. They didn’t call a suspected terrorist on their cell phone. They didn’t try to sneak a machine gun through customs.

They just paid a hefty chunk of their credit card balance. And they learned how frighteningly wide the net of suspicion has been cast.

After sending in the check, they checked online to see if their account had been duly credited. They learned that the check had arrived, but the amount available for credit on their account hadn’t changed.

So Deana Soehnge called the credit-card company. Then Walter called.

“When you mess with my money, I want to know why,” he said.

They both learned the same astounding piece of information about the little things that can set the threat sensors to beeping and blinking.

They were told, as they moved up the managerial ladder at the call center, that the amount they had sent in was much larger than their normal monthly payment. And if the increase hits a certain percentage higher than that normal payment, Homeland Security has to be notified. And the money doesn’t move until the threat alert is lifted.

The article goes on to blame something called the Bank Privacy Act, but that’s not correct. The culprit here is the amendments made to the Bank Secrecy Act by the USA Patriot Act, Sections 351 and 352. There’s a general discussion here, and the Federal Register here.

There has been some rumbling on the net that this story is badly garbled—or even a hoax—but certainly this kind of thing is what financial institutions are required to report under the Patriot Act.

Remember, all the time spent chasing down silly false alarms is time wasted. Finding terrorist plots is a signal-to-noise problem, and stuff like this substantially decreases that ratio: it adds a lot of noise without adding enough signal. It makes us less safe, because it makes terrorist plots harder to find.

Posted on March 6, 2006 at 10:45 AM • View Comments

U.S. Port Security and Proxies

My twelfth essay for Wired.com is about U.S. port security, and more generally about trust and proxies:

Pull aside the rhetoric, and this is everyone’s point. There are those who don’t trust the Bush administration and believe its motivations are political. There are those who don’t trust the UAE because of its terrorist ties—two of the 9/11 terrorists and some of the funding for the attack came out of that country—and those who don’t trust it because of racial prejudices. There are those who don’t trust security at our nation’s ports generally and see this as just another example of the problem.

The solution is openness. The Bush administration needs to better explain how port security works, and the decision process by which the sale of P&O was approved. If this deal doesn’t compromise security, voters—at least the particular lawmakers we trust—need to understand that.

Regardless of the outcome of the Dubai deal, we need more transparency in how our government approaches counter-terrorism in general. Secrecy simply isn’t serving our nation well in this case. It’s not making us safer, and it’s properly reducing faith in our government.

Proxies are a natural outgrowth of society, an inevitable byproduct of specialization. But our proxies are not us and they have different motivations—they simply won’t make the same security decisions as we would. Whether a king is hiring mercenaries, an organization is hiring a network security company or a person is asking some guy to watch his bags while he gets a drink of water, successful security proxies are based on trust. And when it comes to government, trust comes through transparency and openness.

Posted on February 23, 2006 at 7:07 AM • View Comments

Photographing Airports

Patrick Smith, a former pilot, writes about his experiences—involving the police—taking pictures in airports:

He makes sure to remind me, just as his colleague in New Hampshire
had done, that next time I’d benefit from advance permission, and that “we live in a different world now.” Not to put undue weight on the cheap prose of patriotic convenience, but few things are more repellant than that oft- repeated catchphrase. There’s something so pathetically submissive about it—a sound bite of such defeat and capitulation. It’s also untrue; indeed we find ourselves in an altered way of life, though not for the reasons our protectors would have us think. We weren’t forced into this by terrorists, we’ve chosen it. When it comes to flying, we tend to hold the events of Sept. 11 as the be-all and end-all of air crimes, conveniently purging our memories of several decades’ worth of bombings and hijackings. The threats and challenges faced by airports aren’t terribly different from what they’ve always been. What’s different, or “too bad,” to quote the New Hampshire deputy, is our paranoid, overzealous reaction to those threats, and our amped-up obeisance to authority.

Posted on February 22, 2006 at 2:09 PM • View Comments

School Bus Drivers to Foil Terrorist Plots

This is a great example of a movie-plot threat:

Already mindful of motorists with road rage and kids with weapons, bus drivers are being warned of far more grisly scenarios. Like this one: Terrorists monitor a punctual driver for weeks, then hijack a bus and load the friendly yellow vehicle with enough explosives to take down a building.

It’s so bizarre it’s comical.

But don’t worry:

An alert school bus driver could foil that plan, security expert Jeffrey Beatty recently told a class of 250 of drivers in Norfolk, Va.

So we’re funding counterterrorism training for school bus drivers:

Financed by the Homeland Security Department, school bus drivers are being trained to watch for potential terrorists, people who may be casing their routes or plotting to blow up their buses.

[…]

The new effort is part of Highway Watch, an industry safety program run by the American Trucking Associations and financed since 2003 with $50 million in homeland security money.

So far, tens of thousands of bus operators have been trained in places large and small, from Dallas and New York City to Kure Beach, N.C., Hopewell, Va., and Mount Pleasant, Texas.

The commentary borders on the surreal:

Kenneth Trump, a school safety consultant who tracks security trends, said being prepared is not being alarmist. “Denying and downplaying schools and school buses as potential terror targets here in the U.S.,” Trump said, “would be foolish.”

This is certainly a complete waste of money. Possibly it’s even bad for security, as bus drivers have to divide their attention between real threats—automobile accidents involving children—and movie-plot terrorist threats. And there’s the ever-creeping surveillance society:

“Today it’s bus drivers, tomorrow it could be postal officials, and the next day, it could be, ‘Why don’t we have this program in place for the people who deliver the newspaper to the door?’ ” Rollins said. “We could quickly get into a society where we’re all spying on each other. It may be well intentioned, but there is a concern of going a bit too far.”

What should we do this with money instead? We should fund things that actually help defend against terrorism: intelligence, investigation, emergency response. Trying to correctly guess what the terrorists are planning is generally a waste of resources; investing in security countermeasures that will help regardless of what the terrorists are planning is much smarter.

Posted on February 21, 2006 at 9:07 AM • View Comments

Secure Flight Suspended

The TSA has announced that Secure Flight, its comprehensive program to match airline passangers against terrorist watch lists, has been suspended:

And because of security concerns, the government is going back to the drawing board with the program called Secure Flight after spending nearly four years and $150 million on it, the Senate Commerce Committee was told.

I have written about this program extensively, most recently here. It’s an absolute mess in every way, and doesn’t make us safer.

But don’t think this is the end. Under Section 4012 of the Intelligence Reform and Terrorism Prevention Act, Congress mandated the TSA put in place a program to screen every domestic passenger against the watch list. Until Congress repeals that mandate, these postponements and suspensions are the best we can hope for. Expect it all to come back under a different name—and a clean record in the eyes of those not paying close attention—soon.

EDITED TO ADD (2/15): Ed Felton has some good commentary:

Instead of sticking to this more modest plan, Secure Flight became a vehicle for pie-in-the-sky plans about data mining and automatic identification of terrorists from consumer databases. As the program’s goals grew more ambitious and collided with practical design and deployment challenges, the program lost focus and seemed to have a different rationale and plan from one month to the next.

Posted on February 13, 2006 at 6:09 AM • View Comments

The Topology of Covert Conflict

Interesting research paper by Shishir Nagaraja and Ross Anderson. Implications for warfare, terrorism, and peer-to-peer file sharing:

Abstract:

Often an attacker tries to disconnect a network by destroying nodes or edges, while the defender counters using various resilience mechanisms. Examples include a music industry body attempting to close down a peer-to-peer file-sharing network; medics attempting to halt the spread of an infectious disease by selective vaccination; and a police agency trying to decapitate a terrorist organisation. Albert, Jeong and Barabási famously analysed the static case, and showed that vertex-order attacks are effective against scale-free networks. We extend this work to the dynamic case by developing a framework based on evolutionary game theory to explore the interaction of attack and defence strategies. We show, first, that naive defences don’t work against vertex-order attack; second, that defences based on simple redundancy don’t work much better, but that defences based on cliques work well; third, that attacks based on centrality work better against clique defences than vertex-order attacks do; and fourth, that defences based on complex strategies such as delegation plus clique resist centrality attacks better than simple clique defences. Our models thus build a bridge between network analysis and evolutionary game theory, and provide a framework for analysing defence and attack in networks where topology matters. They suggest definitions of efficiency of attack and defence, and may even explain the evolution of insurgent organisations from networks of cells to a more virtual leadership that facilitates operations rather than directing them. Finally, we draw some conclusions and present possible directions for future research.

Posted on February 6, 2006 at 7:03 AM • View Comments

Another No-Fly List Victim

This person didn’t even land in the U.S. His plane flew from Canada to Mexico over U.S. airspace:

Fifteen minutes after the plane left Toronto’s Pearson International Airport, the airline provided customs officials in the United States with a list of passengers. Agents ran the list through a national data base and up popped a name matching Mr. Kahil’s.

[…]

When the plane landed in Acapulco, the Kahils were ushered into a room for questioning. Mug shots were taken of the couple, along with their sons, Karim and Adam, who are 8 and 6. But it was not until a couple of hours later that the Kahils found out why.

Ms. Kahil and the children returned to Canada later that day and Mr. Kahil was put in a detention centre and his passport was confiscated.

Just another case of mistaken identity.

And here’s a story of a four-year-old boy on the watch list.

This program has been a miserable failure in every respect. Not one terrorist caught, ever. (I say this because I believe 100% that if this administration caught anyone through this program, they would be trumpeting it for all to hear.) Thousands of innocents subjected to lengthy and extreme searches every time they fly, prevented from flying, or arrested.

Posted on January 26, 2006 at 3:28 PM • View Comments

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Sidebar photo of Bruce Schneier by Joe MacInnis.