Schneier on Security

A blog covering security and security technology.

Threat Modeling at Microsoft

Interesting paper by Adam Shostack:

Abstract. Describes a decade of experience threat modeling products and services at Microsoft. Describes the current threat modeling methodology used in the Security Development Lifecycle. The methodology is a practical approach, usable by non-experts, centered on data ow diagrams and a threat enumeration technique of 'STRIDE per element.' The paper covers some lessons learned which are likely applicable to other security analysis techniques. The paper closes with some possible questions for academic research.

Posted on October 13, 2008 at 6:21 AM • 4 Comments • View Blog Reactions

Friday Squid Blogging: Natural Squid Steganography

Squid can communicate with each other without any other fish noticing:

Squid and their relatives have eyes that are sensitive to polarised light and to them and are known to use it to signal to one another. Their predators on the other hand, like seals or whales, don't share this ability and cannot see the squids' signals.
Most of all, the polarised iridescent light, is not affected by the chromatophores and passes through unaltered. This means that camouflaged squid can have entire visual conversations while remaining invisible to passing predators. In the world of squid, conversations carry secrets wrapped in lies.

Posted on October 10, 2008 at 4:58 PM • 13 Comments • View Blog Reactions

The More Things Change, the More They Stay the Same

Guess the year:

Murderous organizations have increased in size and scope; they are more daring, they are served by the most terrible weapons offered by modern science, and the world is nowadays threatened by new forces which, if recklessly unchained, may some day wreck universal destruction. The Orsini bombs were mere children's toys compared with the later developments of infernal machines. Between 1858 and 1898 the dastardly science of destruction had made rapid and alarming strides...

No, that wasn't a typo. "Between 1858 and 1898...." This quote is from Major Arthur Griffith, Mysteries of Police and Crime, London, 1898, II, p. 469. It's quoted in: Walter Laqueur, A History of Terrorism, New Brunswick/London, Transaction Publishers, 2002.

Posted on October 10, 2008 at 12:30 PM • 15 Comments • View Blog Reactions

Data Mining for Terrorists Doesn't Work

According to a massive report from the National Research Council, data mining for terrorists doesn't work. Here's a good summary:

The report was written by a committee whose members include William Perry, a professor at Stanford University; Charles Vest, the former president of MIT; W. Earl Boebert, a retired senior scientist at Sandia National Laboratories; Cynthia Dwork of Microsoft Research; R. Gil Kerlikowske, Seattle's police chief; and Daryl Pregibon, a research scientist at Google.
They admit that far more Americans live their lives online, using everything from VoIP phones to Facebook to RFID tags in automobiles, than a decade ago, and the databases created by those activities are tempting targets for federal agencies. And they draw a distinction between subject-based data mining (starting with one individual and looking for connections) compared with pattern-based data mining (looking for anomalous activities that could show illegal activities).

But the authors conclude the type of data mining that government bureaucrats would like to do--perhaps inspired by watching too many episodes of the Fox series 24--can't work. "If it were possible to automatically find the digital tracks of terrorists and automatically monitor only the communications of terrorists, public policy choices in this domain would be much simpler. But it is not possible to do so."

A summary of the recommendations:

U.S. government agencies should be required to follow a systematic process to evaluate the effectiveness, lawfulness, and consistency with U.S. values of every information-based program, whether classified or unclassified, for detecting and countering terrorists before it can be deployed, and periodically thereafter.
Periodically after a program has been operationally deployed, and in particular before a program enters a new phase in its life cycle, policy makers should (carefully review) the program before allowing it to continue operations or to proceed to the next phase.

To protect the privacy of innocent people, the research and development of any information-based counterterrorism program should be conducted with synthetic population data... At all stages of a phased deployment, data about individuals should be rigorously subjected to the full safeguards of the framework.

Any information-based counterterrorism program of the U.S. government should be subjected to robust, independent oversight of the operations of that program, a part of which would entail a practice of using the same data mining technologies to "mine the miners and track the trackers."

Counterterrorism programs should provide meaningful redress to any individuals inappropriately harmed by their operation.

The U.S. government should periodically review the nation's laws, policies, and procedures that protect individuals' private information for relevance and effectiveness in light of changing technologies and circumstances. In particular, Congress should re-examine existing law to consider how privacy should be protected in the context of information-based programs (e.g., data mining) for counterterrorism.

Here are more news articles on the report. I explained why data mining wouldn't find terrorists back in 2005.

EDITED TO ADD (10/10): More commentary:

As the NRC report points out, not only is the training data lacking, but the input data that you'd actually be mining has been purposely corrupted by the terrorists themselves. Terrorist plotters actively disguise their activities using operational security measures (opsec) like code words, encryption, and other forms of covert communication. So, even if we had access to a copious and pristine body of training data that we could use to generalize about the "typical terrorist," the new data that's coming into the data mining system is suspect.
To return to the credit reporting analogy, credit scores would be worthless to lenders if everyone could manipulate their credit history (e.g., hide past delinquencies) the way that terrorists can manipulate the data trails that they leave as they buy gas, enter buildings, make phone calls, surf the Internet, etc.

So this application of data mining bumps up against the classic GIGO (garbage in, garbage out) problem in computing, with the terrorists deliberately feeding the system garbage. What this means in real-world terms is that the success of our counter-terrorism data mining efforts is completely dependent on the failure of terrorist cells to maintain operational security.

The combination of the GIGO problem and the lack of suitable training data combine to make big investments in automated terrorist identification a futile and wasteful effort. Furthermore, these two problems are structural, so they're not going away. All legitimate concerns about false positives and corrosive effects on civil liberties aside, data mining will never give authorities the ability to identify terrorists or terrorist networks with any degree of confidence.

Posted on October 10, 2008 at 6:35 AM • 19 Comments • View Blog Reactions

Nonviolent Activists Are Now Terrorists

Heard about this:

The Maryland State Police classified 53 nonviolent activists as terrorists and entered their names and personal information into state and federal databases that track terrorism suspects, the state police chief acknowledged yesterday.

Why did they do that?

Both Hutchins and Sheridan said the activists' names were entered into the state police database as terrorists partly because the software offered limited options for classifying entries.

I know that once we had this "either you're with us or with the terrorists" mentality, but don't you think that -- just maybe -- the software should allow for a little bit more nuance?

Posted on October 9, 2008 at 1:07 PM • 51 Comments • View Blog Reactions

"New Attack" Against Encrypted Images

In a blatant attempt to get some PR:

In a new paper, Bernd Roellgen of Munich-based encryption outfit PMC Ciphers, explains how it is possible to compare an encrypted backup image file made with almost any commercial encryption program or algorithm to an original that has subsequently changed so that small but telling quantities of data 'leaks'.

Here's the paper. Turns out that if you use a block cipher in Electronic Codebook Mode, identical plaintexts encrypt to identical ciphertexts.

Yeah, we already knew that.

And -1 point for a security company requiring the use of Javascript, and not failing gracefully for a browser that doesn't have it enabled.

And -- ahem -- what is it with that photograph in the paper? Couldn't the researchers have found something a little less adolescent?

For the record, I doghoused PMC Ciphers back in 2003:

PMC Ciphers. The theory description is so filled with pseudo-cryptography that it's funny to read. Hypotheses are presented as conclusions. Current research is misstated or ignored. The first link is a technical paper with four references, three of them written before 1975. Who needs thirty years of cryptographic research when you have polymorphic cipher theory?

EDITED TO ADD (10/9): I didn't realize it, but last year PMC Ciphers responded to my doghousing them. Funny stuff.

EDITED TO ADD (10/10): I'm sure you won't be shocked to discover that the three people defending the PMC Ciphers paper in the comments all come from dialups at the same German ISP.

Posted on October 9, 2008 at 6:44 AM • 54 Comments • View Blog Reactions

Chinese Monitoring Skype Messages

This is the best article I've read on the story.

Posted on October 8, 2008 at 6:55 AM • 9 Comments • View Blog Reactions

Do-Not-Call Lists

Turns out you can add anyone's number -- or remove anyone's number -- to/from the Canadian do-not-call list. You can also add (but not remove) numbers to the U.S. do-not-call list, though only up to three at a time, and you have to provide a valid e-mail address to confirm the addition.

Here's my idea. If you're a company, add every one of your customers to the list. That way, none of your competitors will be able to cold call them.

Posted on October 7, 2008 at 3:51 PM • 41 Comments • View Blog Reactions

The Seven Habits of Highly Ineffective Terrorists

Most counterterrorism policies fail, not because of tactical problems, but because of a fundamental misunderstanding of what motivates terrorists in the first place. If we're ever going to defeat terrorism, we need to understand what drives people to become terrorists in the first place.

Conventional wisdom holds that terrorism is inherently political, and that people become terrorists for political reasons. This is the "strategic" model of terrorism, and it's basically an economic model. It posits that people resort to terrorism when they believe -- rightly or wrongly -- that terrorism is worth it; that is, when they believe the political gains of terrorism minus the political costs are greater than if they engaged in some other, more peaceful form of protest. It's assumed, for example, that people join Hamas to achieve a Palestinian state; that people join the PKK to attain a Kurdish national homeland; and that people join al-Qaida to, among other things, get the United States out of the Persian Gulf.

If you believe this model, the way to fight terrorism is to change that equation, and that's what most experts advocate. Governments tend to minimize the political gains of terrorism through a no-concessions policy; the international community tends to recommend reducing the political grievances of terrorists via appeasement, in hopes of getting them to renounce violence. Both advocate policies to provide effective nonviolent alternatives, like free elections.

Historically, none of these solutions has worked with any regularity. Max Abrahms, a predoctoral fellow at Stanford University's Center for International Security and Cooperation, has studied dozens of terrorist groups from all over the world. He argues that the model is wrong. In a paper published this year in International Security that -- sadly -- doesn't have the title "Seven Habits of Highly Ineffective Terrorists," he discusses, well, seven habits of highly ineffective terrorists. These seven tendencies are seen in terrorist organizations all over the world, and they directly contradict the theory that terrorists are political maximizers:

Terrorists, he writes, (1) attack civilians, a policy that has a lousy track record of convincing those civilians to give the terrorists what they want; (2) treat terrorism as a first resort, not a last resort, failing to embrace nonviolent alternatives like elections; (3) don't compromise with their target country, even when those compromises are in their best interest politically; (4) have protean political platforms, which regularly, and sometimes radically, change; (5) often engage in anonymous attacks, which precludes the target countries making political concessions to them; (6) regularly attack other terrorist groups with the same political platform; and (7) resist disbanding, even when they consistently fail to achieve their political objectives or when their stated political objectives have been achieved.

Abrahms has an alternative model to explain all this: People turn to terrorism for social solidarity. He theorizes that people join terrorist organizations worldwide in order to be part of a community, much like the reason inner-city youths join gangs in the United States.

The evidence supports this. Individual terrorists often have no prior involvement with a group's political agenda, and often join multiple terrorist groups with incompatible platforms. Individuals who join terrorist groups are frequently not oppressed in any way, and often can't describe the political goals of their organizations. People who join terrorist groups most often have friends or relatives who are members of the group, and the great majority of terrorist are socially isolated: unmarried young men or widowed women who weren't working prior to joining. These things are true for members of terrorist groups as diverse as the IRA and al-Qaida.

For example, several of the 9/11 hijackers planned to fight in Chechnya, but they didn't have the right paperwork so they attacked America instead. The mujahedeen had no idea whom they would attack after the Soviets withdrew from Afghanistan, so they sat around until they came up with a new enemy: America. Pakistani terrorists regularly defect to another terrorist group with a totally different political platform. Many new al-Qaida members say, unconvincingly, that they decided to become a jihadist after reading an extreme, anti-American blog, or after converting to Islam, sometimes just a few weeks before. These people know little about politics or Islam, and they frankly don't even seem to care much about learning more. The blogs they turn to don't have a lot of substance in these areas, even though more informative blogs do exist.

All of this explains the seven habits. It's not that they're ineffective; it's that they have a different goal. They might not be effective politically, but they are effective socially: They all help preserve the group's existence and cohesion.

This kind of analysis isn't just theoretical; it has practical implications for counterterrorism. Not only can we now better understand who is likely to become a terrorist, we can engage in strategies specifically designed to weaken the social bonds within terrorist organizations. Driving a wedge between group members -- commuting prison sentences in exchange for actionable intelligence, planting more double agents within terrorist groups -- will go a long way to weakening the social bonds within those groups.

We also need to pay more attention to the socially marginalized than to the politically downtrodden, like unassimilated communities in Western countries. We need to support vibrant, benign communities and organizations as alternative ways for potential terrorists to get the social cohesion they need. And finally, we need to minimize collateral damage in our counterterrorism operations, as well as clamping down on bigotry and hate crimes, which just creates more dislocation and social isolation, and the inevitable calls for revenge.

This essay previously appeared on Wired.com.

EDITED TO ADD (10/9): Interesting rebuttal.

Posted on October 7, 2008 at 5:48 AM • 82 Comments • View Blog Reactions

Clickjacking

Good Q&A on clickjacking:

In plain English, clickjacking lets hackers and scammers hide malicious stuff under the cover of the content on a legitimate site. You know what happens when a carjacker takes a car? Well, clickjacking is like that, except that the click is the car.

"Clickjacking" is a stunningly sexy name, but the vulnerability is really just a variant of cross-site scripting. We don't know how bad it really is, because the details are still being withheld. But the name alone is causing dread.

Posted on October 6, 2008 at 1:45 PM • 25 Comments • View Blog Reactions

New Cross-Site Request Forgery Attacks

Interesting:

CSRF vulnerabilities occur when a website allows an authenticated user to perform a sensitive action but does not verify that the user herself is invoking that action. The key to understanding CSRF attacks is to recognize that websites typically don't verify that a request came from an authorized user. Instead they verify only that the request came from the browser of an authorized user. Because browsers run code sent by multiple sites, there is a danger that one site will (unbeknownst to the user) send a request to a second site, and the second site will mistakenly think that the user authorized the request.
If a user visits an attacker's website, the attacker can force the user's browser to send a request to a page that performs a sensitive action on behalf of the user. The target website sees a request coming from an authenticated user and happily performs some action, whether it was invoked by the user or not. CSRF attacks have been confused with Cross-Site Scripting (XSS) attacks, but they are very different. A site completely protected from XSS is still vulnerable to CSRF attacks if no protections are taken.

Paper here.

Posted on October 6, 2008 at 5:42 AM • 26 Comments • View Blog Reactions