However, it turns out there’s other effects as well. In a paper I presented last week to the Fifth Conference on Email and Anti-Spam (CEAS 2008), I showed that the first letter of the local part of the email address also plays a part.

Incoming email to Demon Internet where the email address local part (the bit left of the @) begins with “A” (think of these as aardvarks) is almost exactly 50% spam and 50% non-spam. However, where the local part begins with “Z” (zebras) then it is about 75% spam.

However, if one only considers “real” aardvarks and zebras, viz: where a particular email address was legitimate enough to receive some non-spam email, then the picture changes. If one treats an email address as “real” if there’s one non-spam email on average every second day, then real aardvarks receive 35% spam, but real zebras receive only 20% spam.

The most likely reason for these results is the prevalence of “dictionary” or “Rumpelstiltskin” attacks (where spammers guess addresses). If there are not many other zebras, then guessing zebra names is less likely.

Aardvarks should consider changing species — or asking their favourite email filter designer to think about how this unexpected empirical result can be leveraged into blocking more of their unwanted email.

[[[ ** Note that these percentages are way down from general spam rates because Demon rejects out of hand email from sites listed in the PBL (which are not expected to send email) and greylists email from sites in the ZEN list. This reduces overall volumes considerably -- so YMMV! ]]]

The designer, Carter Bryant, has been accused by Mattel of using Evidence Eliminator on his laptop computer just two days before investigators were due to copy its hard drive. Carter hasn't denied that the program was run on his computer, but he said it wasn't to destroy evidence. He said he had legitimate reasons to use the software. [...] But the wiper programs don't ensure a clean getaway. They leave behind a kind of digital calling card. "Not only do these programs leave a trace that they were used, they each have a distinctive fingerprint," Kessler said. "Evidence Eliminator leaves one that's different from Window Washer, and so on." It's the kind of information that can be brought up in court. And if the digital calling card was left by Evidence Eliminator, it could raise some eyebrows, even if the wiper was used for the most innocent of reasons.

Vulnerabilities are software mistakes--mistakes in specification and design, but mostly mistakes in programming. Any large software package will have thousands of mistakes. These vulnerabilities lie dormant in our software systems, waiting to be discovered. Once discovered, they can be used to attack systems. This is the point of security patching: eliminating known vulnerabilities. But many systems don't get patched, so the Internet is filled with known, exploitable vulnerabilities.

New vulnerabilities are hot commodities. A hacker who discovers one can sell it on the black market, blackmail the vendor with disclosure, or simply publish it without regard to the consequences. Even if he does none of these, the mere fact the vulnerability is known by someone increases the risk to every user of that software. Given that, is it ethical to research new vulnerabilities?

Unequivocally, yes. Despite the risks, vulnerability research is enormously valuable. Security is a mindset, and looking for vulnerabilities nurtures that mindset. Deny practitioners this vital learning tool, and security suffers accordingly.

Security engineers see the world differently than other engineers. Instead of focusing on how systems work, they focus on how systems fail, how they can be made to fail, and how to prevent--or protect against--those failures. Most software vulnerabilities don't ever appear in normal operations, only when an attacker deliberately exploits them. So security engineers need to think like attackers.

People without the mindset sometimes think they can design security products, but they can't. And you see the results all over society--in snake-oil cryptography, software, Internet protocols, voting machines, and fare card and other payment systems. Many of these systems had someone in charge of "security" on their teams, but it wasn't someone who thought like an attacker.

This mindset is difficult to teach, and may be something you're born with or not. But in order to train people possessing the mindset, they need to search for and find security vulnerabilities--again and again and again. And this is true regardless of the domain. Good cryptographers discover vulnerabilities in others' algorithms and protocols. Good software security experts find vulnerabilities in others' code. Good airport security designers figure out new ways to subvert airport security. And so on.

This is so important that when someone shows me a security design by someone I don't know, my first question is, "What has the designer broken?" Anyone can design a security system that he cannot break. So when someone announces, "Here's my security system, and I can't break it," your first reaction should be, "Who are you?" If he's someone who has broken dozens of similar systems, his system is worth looking at. If he's never broken anything, the chance is zero that it will be any good.

Vulnerability research is vital because it trains our next generation of computer security experts. Yes, newly discovered vulnerabilities in software and airports put us at risk, but they also give us more realistic information about how good the security actually is. And yes, there are more and less responsible--and more and less legal--ways to handle a new vulnerability. But the bad guys are constantly searching for new vulnerabilities, and if we have any hope of securing our systems, we need the good guys to be at least as competent. To me, the question isn't whether it's ethical to do vulnerability research. If someone has the skill to analyze and provide better insights into the problem, the question is whether it is ethical for him not to do vulnerability research.

This was originally published in InfoSecurity Magazine, as part of a point-counterpoint with Marcus Ranum. You can read Marcus's half here.

In development for more than 30 years, the research is beginning to bear fruit, and may soon spawn more powerful bombs, warheads that tear apart stone and concrete, mines that can be set to stun or kill, and grenades that can swat rockets or mortar rounds out of the sky like flies.

"You can get effects that are more precisely tailored to a particular target," says John Pike, director of Washington military research group GlobalSecurity.org. "And you're able to get a greater effect out of a smaller munition."

Reactive materials are combinations of materials that are normally stable, but, when subjected to sudden shock -- such as striking a target -- release a large amount of energy. Depending on the composition and warhead design, the energy can be released as heat, a blast or a combination of the two. Unlike conventional explosives, RMs cannot be set off by fuses. Technically, they are classified as flammable solids, and they are less hazardous to transport and store than explosives.

While they're more energetic than explosives, RMs are not intended to be a substitute. Instead, they will replace warhead components normally made of metal.

An analysis of U.S. military procurement papers and defense contractor presentations, as well as interviews with companies working on the technology, suggests that a wave of munitions using reactive materials may be headed for a battlefield near you.

The material can dramatically magnify the yield of conventional bombs, and do away with the waste embodied by a bomb's inert metal skin. The U.S. Air Force's 5,000 BLU-122 bunker buster, for example, contains just 780 pounds of explosives; the other 80 percent is the bomb's thick steel casing. DARPA's Reactive Munition program (.doc) aims to replace that steel with RMs, to create a bomb with a blast four times as powerful. Alternatively, a new bomb could be half the size of existing weapons but twice as powerful.

Conventional warheads could also benefit from an RM makeover. For centuries, shells have blasted out steel shrapnel, small pieces of metal that cause damage with their high speed. Defense contractor Alliant Techsystems is developing a warhead called BattleAxe for the Air Force that uses fragments made of RM instead of metal. Those fragments will explode on impact, making the warhead far more effective against soft targets like trucks.

RM shrapnel is also being touted as the ideal way of shooting down incoming rockets and mortar bombs (.pdf).

A radar-guided defense pod can automatically engage incoming rockets or other threats using RM-based grenades. Weapons designers suggest that RMs can be five to ten times as effective as the existing inert shrapnel for this task. Moreover, RM shrapnel can be engineered to burn out at a set distance, so there is no hazard to nearby friendly forces.

Bullets can even be made of RM. The Navy's new electromagnetic railgun has been criticized because it can only fire solid slugs, not the usual explosive shells. However, documents reveal that tungsten-based RM rounds are being developed for the weapon. These will explode on impact, making the railgun effective against buildings, ships and vehicles.

Shaped charges are another application where RMs can increase the effectiveness of existing designs. In a shaped charge, a hollow metal cone is surrounded by explosive material, which is then detonated, forcing the blast through the small end of the cone.

"The action is analogous to stamping on an open toothpaste tube, ejecting the liquid contents," says Douglas Millard of British defense contractors QinetiQ.

Replace the metal liner with RM, and the explosive power of that jet will increase dramatically.

"Such reactions are highly exothermic and therefore lead to the release of large amounts of energy, which is in addition to the kinetic energy within the jet," Millard says. "An increase in the energy coupled into the target occurs and this results in the creation of greater damage to the target."

QinetiQ is marketing an RM-based shaped charge called Connex for oil-well perforation in the civil market. Meanwhile, the U.S. Army is developing a demolition charge called Bam Bam that blasts a jet of RM deep into stone or concrete, producing massive damage

One version of the Bam Bam charge is intended for demolishing bridges and other structures. An alternative version blasts broader, shallower craters in roads or runways, making them useless.

RMs will also transform another mutation called the Explosively Formed Penetrator, a modified version of the shaped charge. Instead of producing a narrow, short-range jet, the Penetrator fires an aerodynamic slug of metal over a long distance. It's best known as a favored weapon of insurgents in Iraq. Again, replacing the metal with RM makes a much deadlier weapon -- after punching through armor, the slug releases energy like a grenade going off.

If you're a weapons designer, RMs also offer amazing flexibility. Alliant Techsystems is building a variable landmine (.pps) -- a so-called "dial-a-yield" weapon that can produce a range of different effects.

At the lowest setting, most of the output would be light -- a dazzling warning that would be impossible to miss. A higher setting would produce intense heat, creating a "discomfort zone" to drive off intruders. The third setting produces a nonlethal blast, like the concussion stun grenades used by Special Forces. If lethal force is called for, the mine could be set to produce either inert shrapnel or reactive shrapnel that explodes on impact.

RM munitions may face legal challenges. Under the St. Petersburg Declaration of 1868, the use of explosive projectiles with a weight of less than 400 grams is forbidden, as is using incendiary ammunition, like napalm, against personnel. But RMs are not technically explosive or incendiary, and although the effect on human targets might cause protests from some groups, they are likely to be accepted, human rights experts say.

"Like any weapon, it would have to go through a lengthy effectiveness and then legal review, " says Marc Garlasco, senior military analyst at Human Rights Watch. "If used in the open against military targets, it does not seem to have any obvious problems at first blush."

However, there may be technology issues too. Although the developers sound very upbeat in all their descriptions of RM munitions, producing material that will reliably release energy only when required is extremely challenging.

"The fact that they've been working on it so long and don't seem to have fielded anything yet suggests that there may be a problem with the technology," GlobalSecurity's Pike says.

Normally new weapons are fielded rapidly if there is a military demand -- assuming they work. So far, RMs have not made it into the field, and the technology may not be as mature as developers suggest.

But Pike also notes that there has been an unprecedented surge in munitions development over the last few years, with "all kinds of weird stuff" being developed.

So after decades of being kept very quiet, reactive materials may soon be making a lot of noise.

---

Check out Danger Room for more on reactive materials.

Took the kids to see Iron Man tonight with our cousins Jeri and Danny.  I generally like Robert Downey, Jr and he acted very hard in this movie. However, I just didn't get the story. I remember watching Iron Man cartoons when I was little and reading the comic books, there was some special thing about Iron Man's blood the way I remember it that gave him super hero powers.

In the movie incarnation, Tony Starks is the son of a weapons designer and a brilliant weapons designer himself.  However, he has some serious character flaws. He is kidnapped by some sort of mid-eastern terrorists and take some shrapnel in his chest.  A doctor attaches an electromagnet to a car battery on his chest to keep the shrapnel from going into his heart. Downey then designs some sort of mini-power source to power the electromagnet,  He uses the power source to power a metal suit he builds (long story) and escapes from the terrorists.  From there the movie is fairly predictable and frankly in my opinion not very good.  I didn't understand how he got the superpower, it was just a powered suit and how it worked was pretty silly. 

The ultimate thumbs up or down for me was that both of my sons fell asleep in the movie theater.  The good news is that this is the start of the summer movie season. I am really looking forward to Indiana Jones and the kids want to see Speed Racer!

In order to register for the online system I need to supply an email address and a password (”at least 8 characters long and contain at least 1 numeric or non-alphabetic character”). So far so good.

If I forget this password, I will be required to answer two security questions, which I get to choose from a little shortlist. They’ve eschewed “mother’s maiden name”, but the system designer seems to have copied them from Bebo or Disney’s Mickey Mouse Club:

• Name of your favourite entertainer?
• Your main childhood phone number?
• Your favourite place to visit as a child?
• Name of your favourite teacher?
• Your grandfather’s occupation?
• Your best childhood friend?
• Name your childhood hero?

Since most pension fund trustees, the people who have to provide good answers to these questions, will be in their 50’s and 60’s, these questions are quite clearly unsuitable.

I’ve gone with the last two… each of which turn out to be different from the password, but the answers, weirdly enough, are also at least 8 characters long and contain at least one numeric or non-alphabetic character!