Essays in the Category "Computer and Information Security"
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The Vulnerabilities Market and the Future of Security
Brazilian Portuguese translation
Recently, there have been several articles about the new market in zero-day exploits: new and unpatched computer vulnerabilities. It’s not just software companies, who sometimes pay bounties to researchers who alert them of security vulnerabilities so they can fix them. And it’s not only criminal organizations, who pay for vulnerabilities they can exploit. Now there are governments, and companies who sell to governments, who buy vulnerabilities with the intent of keeping them secret so they can exploit them.
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Schneier-Ranum Face-Off on Whitelisting and Blacklisting
This essay appeared as the second half of a point/counterpoint with Marcus Ranum.
The whitelist/blacklist debate is far older than computers, and it’s instructive to recall what works where. Physical security works generally on a whitelist model: if you have a key, you can open the door; if you know the combination, you can open the lock. We do it this way not because it’s easier—although it is generally much easier to make a list of people who should be allowed through your office door than a list of people who shouldn’t—but because it’s a security system that can be implemented automatically, without people…
The Plan to Quarantine Infected Computers
Keeping infected computers at bay is great in theory, but there are all sorts of complicating factors to consider.
Last month Scott Charney of Microsoft proposed that infected computers be quarantined from the Internet. Using a public health model for Internet security, the idea is that infected computers spreading worms and viruses are a risk to the greater community and thus need to be isolated. Internet service providers would administer the quarantine, and would also clean up and update users’ computers so they could rejoin the greater Internet.
This isn’t a new idea. Already there are products that test computers trying to join private networks, and only allow them access if their security patches are up-to-date and their antivirus software certifies them as clean. Computers denied access are sometimes shunned to a limited-capability sub-network where all they can do is download and install the updates they need to regain access. This sort of system has been used with great success at universities and end-user-device-friendly corporate networks. They’re happy to let you log in with any device you want—this is the consumerization trend in action—as long as your security is up to snuff…
When to Change Passwords
How often should you change your password? I get asked that question a lot, usually by people annoyed at their employer’s or bank’s password expiration policy—people who finally memorized their current password and are realizing they’ll have to write down their new one. How could that possibly be more secure, they want to know.
The answer depends on what the password is used for.
The downside of changing passwords is that it makes them harder to remember. And if you force people to change their passwords regularly, they’re more likely to choose easy-to-remember—and easy-to-guess—passwords than they are if they can use the same passwords for many years. So any password-changing policy needs to be chosen with that consideration in mind…
The Dangers of a Software Monoculture
This essay appeared as the first half of a point-counterpoint with Marcus Ranum. Marcus’s half is here.
In 2003, a group of security experts—myself included—published a paper saying that 1) software monocultures are dangerous and 2) Microsoft, being the largest creator of monocultures out there, is the most dangerous. Marcus Ranum responded with an essay that basically said we were full of it. Now, eight years later, Marcus and I thought it would be interesting to revisit the debate.
The basic problem with a monoculture is that it’s all vulnerable to the same attack. The Irish Potato Famine of 1845—9 is perhaps the most famous monoculture-related disaster. The Irish planted only one variety of potato, and the genetically identical potatoes succumbed to a rot caused by Phytophthora infestans. Compare that with the diversity of potatoes traditionally grown in South America, each one adapted to the particular soil and climate of its home, and you can see the security value in heterogeneity…
The Story Behind The Stuxnet Virus
Computer security experts are often surprised at which stories get picked up by the mainstream media. Sometimes it makes no sense. Why this particular data breach, vulnerability, or worm and not others? Sometimes it’s obvious. In the case of Stuxnet, there’s a great story.
As the story goes, the Stuxnet worm was designed and released by a government—the U.S. and Israel are the most common suspects—specifically to attack the Bushehr nuclear power plant in Iran. How could anyone not report that? It combines computer attacks, nuclear power, spy agencies and a country that’s a pariah to much of the world. The only problem with the story is that it’s almost entirely speculation…
Should Enterprises Give In to IT Consumerization at the Expense of Security?
This essay appeared as the second half of a point/counterpoint with Marcus Ranum.
If you’re a typical wired American, you’ve got a bunch of tech tools you like and a bunch more you covet. You have a cell phone that can easily text. You’ve got a laptop configured just the way you want it. Maybe you have a Kindle for reading, or an iPad. And when the next new thing comes along, some of you will line up on the first day it’s available.
So why can’t work keep up? Why are you forced to use an unfamiliar, and sometimes outdated, operating system? Why do you need a second laptop, maybe an older and clunkier one? Why do you need a second cell phone with a new interface, or a BlackBerry, when your phone already does e-mail? Or a second BlackBerry tied to corporate e-mail? Why can’t you use the cool stuff you already have?…
3 Reasons to Kill the Internet Kill Switch Idea
Last month, Sen. Joe Lieberman, I-Conn., introduced a bill that might—we’re not really sure—give the president the authority to shut down all or portions of the Internet in the event of an emergency. It’s not a new idea. Sens. Jay Rockefeller, D-W.Va., and Olympia Snowe, R-Maine, proposed the same thing last year, and some argue that the president can already do something like this. If this or a similar bill ever passes, the details will change considerably and repeatedly. So let’s talk about the idea of an Internet kill switch in general.
It’s a bad one…
Threat of "Cyberwar" Has Been Hugely Hyped
There’s a power struggle going on in the U.S. government right now.
It’s about who is in charge of cyber security, and how much control the government will exert over civilian networks. And by beating the drums of war, the military is coming out on top.
“The United States is fighting a cyberwar today, and we are losing,” said former NSA director—and current cyberwar contractor—Mike McConnell. “Cyber 9/11 has happened over the last ten years, but it happened slowly so we don’t see it,” said former National Cyber Security Division director Amit Yoran. Richard Clarke, whom Yoran replaced, wrote an entire …
The Failure of Cryptography to Secure Modern Networks
For a while now, I’ve pointed out that cryptography is singularly ill-suited to solve the major network security problems of today: denial-of-service attacks, website defacement, theft of credit card numbers, identity theft, viruses and worms, DNS attacks, network penetration, and so on.
Cryptography was invented to protect communications: data in motion. This is how cryptography was used throughout most of history, and this is how the militaries of the world developed the science. Alice was the sender, Bob the receiver, and Eve the eavesdropper. Even when cryptography was used to protect stored data—data at rest—it was viewed as a form of communication. In “Applied Cryptography,” I described encrypting stored data in this way: “a stored message is a way for someone to communicate with himself through time.” Data storage was just a subset of data communication…
Sidebar photo of Bruce Schneier by Joe MacInnis.