Entries Tagged "computer security"

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Making an Operating System Virus Free

Commenting on Google’s claim that Chrome was designed to be virus-free, I said:

Bruce Schneier, the chief security technology officer at BT, scoffed at Google’s promise. “It’s an idiotic claim,” Schneier wrote in an e-mail. “It was mathematically proved decades ago that it is impossible—not an engineering impossibility, not technologically impossible, but the 2+2=3 kind of impossible—to create an operating system that is immune to viruses.”

What I was referring to, although I couldn’t think of his name at the time, was Fred Cohen’s 1986 Ph.D. thesis where he proved that it was impossible to create a virus-checking program that was perfect. That is, it is always possible to write a virus that any virus-checking program will not detect.

This reaction to my comment is accurate:

That seems to us like he’s picking on the semantics of Google’s statement just a bit. Google says that users “won’t have to deal with viruses,” and Schneier is noting that it’s simply not possible to create an OS that can’t be taken down by malware. While that may be the case, it’s likely that Chrome OS is going to be arguably more secure than the other consumer operating systems currently in use today. In fact, we didn’t take Google’s statement to mean that Chrome OS couldn’t get a virus EVER; we just figured they meant it was a lot harder to get one on their new OS – didn’t you?

When I said that I had not seen Google’s statement. I was responding to what the reporter was telling me on the phone. So yes, I jumped on the reporter’s claim about Google’s claim. I did try to temper my comment:

Redesigning an operating system from scratch, “[taking] security into account all the way up and down,” could make for a more secure OS than ones that have been developed so far, Schneier said. But that’s different from Google’s promise that users won’t have to deal with viruses or malware, he added.

To summarize, there is a lot that can be done in an OS to reduce the threat of viruses and other malware. If the Chrome team started from scratch and took security seriously all through the design and development process, they have to potential to develop something really secure. But I don’t know if they did.

Posted on July 10, 2009 at 9:44 AM • View Comments

The Pros and Cons of Password Masking

Usability guru Jakob Nielsen opened up a can of worms when he made the case for unmasking passwords in his blog. I chimed in that I agreed. Almost 165 comments on my blog (and several articles, essays, and many other blog posts) later, the consensus is that we were wrong.

I was certainly too glib. Like any security countermeasure, password masking has value. But like any countermeasure, password masking is not a panacea. And the costs of password masking need to be balanced with the benefits.

The cost is accuracy. When users don’t get visual feedback from what they’re typing, they’re more prone to make mistakes. This is especially true with character strings that have non-standard characters and capitalization. This has several ancillary costs:

  • Users get pissed off.
  • Users are more likely to choose easy-to-type passwords, reducing both mistakes and security. Removing password masking will make people more comfortable with complicated passwords: they’ll become easier to memorize and easier to use.

The benefits of password masking are more obvious:

  • Security from shoulder surfing. If people can’t look over your shoulder and see what you’re typing, they’re much less likely to be able to steal your password. Yes, they can look at your fingers instead, but that’s much harder than looking at the screen. Surveillance cameras are also an issue: it’s easier to watch someone’s fingers on recorded video, but reading a cleartext password off a screen is trivial.

    In some situations, there is a trust dynamic involved. Do you type your password while your boss is standing over your shoulder watching? How about your spouse or partner? Your parent or child? Your teacher or students? At ATMs, there’s a social convention of standing away from someone using the machine, but that convention doesn’t apply to computers. You might not trust the person standing next to you enough to let him see your password, but don’t feel comfortable telling him to look away. Password masking solves that social awkwardness.

  • Security from screen scraping malware. This is less of an issue; keyboard loggers are more common and unaffected by password masking. And if you have that kind of malware on your computer, you’ve got all sorts of problems.
  • A security “signal.” Password masking alerts users, and I’m thinking users who aren’t particularly security savvy, that passwords are a secret.

I believe that shoulder surfing isn’t nearly the problem it’s made out to be. One, lots of people use their computers in private, with no one looking over their shoulders. Two, personal handheld devices are used very close to the body, making shoulder surfing all that much harder. Three, it’s hard to quickly and accurately memorize a random non-alphanumeric string that flashes on the screen for a second or so.

This is not to say that shoulder surfing isn’t a threat. It is. And, as many readers pointed out, password masking is one of the reasons it isn’t more of a threat. And the threat is greater for those who are not fluent computer users: slow typists and people who are likely to choose bad passwords. But I believe that the risks are overstated.

Password masking is definitely important on public terminals with short PINs. (I’m thinking of ATMs.) The value of the PIN is large, shoulder surfing is more common, and a four-digit PIN is easy to remember in any case.

And lastly, this problem largely disappears on the Internet on your personal computer. Most browsers include the ability to save and then automatically populate password fields, making the usability problem go away at the expense of another security problem (the security of the password becomes the security of the computer). There’s a Firefox plugin that gets rid of password masking. And programs like my own Password Safe allow passwords to be cut and pasted into applications, also eliminating the usability problem.

One approach is to make it a configurable option. High-risk banking applications could turn password masking on by default; other applications could turn it off by default. Browsers in public locations could turn it on by default. I like this, but it complicates the user interface.

A reader mentioned BlackBerry’s solution, which is to display each character briefly before masking it; that seems like an excellent compromise.

I, for one, would like the option. I cannot type complicated WEP keys into Windows—twice! what’s the deal with that?—without making mistakes. I cannot type my rarely used and very complicated PGP keys without making a mistake unless I turn off password masking. That’s what I was reacting to when I said “I agree.”

So was I wrong? Maybe. Okay, probably. Password masking definitely improves security; many readers pointed out that they regularly use their computer in crowded environments, and rely on password masking to protect their passwords. On the other hand, password masking reduces accuracy and makes it less likely that users will choose secure and hard-to-remember passwords, I will concede that the password masking trade-off is more beneficial than I thought in my snap reaction, but also that the answer is not nearly as obvious as we have historically assumed.

Posted on July 3, 2009 at 1:42 PM • View Comments

The Problem with Password Masking

I agree with this:

It’s time to show most passwords in clear text as users type them. Providing feedback and visualizing the system’s status have always been among the most basic usability principles. Showing undifferentiated bullets while users enter complex codes definitely fails to comply.

Most websites (and many other applications) mask passwords as users type them, and thereby theoretically prevent miscreants from looking over users’ shoulders. Of course, a truly skilled criminal can simply look at the keyboard and note which keys are being pressed. So, password masking doesn’t even protect fully against snoopers.

More importantly, there’s usually nobody looking over your shoulder when you log in to a website. It’s just you, sitting all alone in your office, suffering reduced usability to protect against a non-issue.

Shoulder surfing isn’t very common, and cleartext passwords greatly reduces errors. It has long annoyed me when I can’t see what I type: in Windows logins, in PGP, and so on.

EDITED TO ADD (6/26): To be clear, I’m not talking about PIN masking on public terminals like ATMs. I’m talking about password masking on personal computers.

EDITED TO ADD (6/30): Two articles on the subject.

Posted on June 26, 2009 at 6:17 AM • View Comments

Second SHB Workshop Liveblogging (3)

The second session was about fraud. (These session subjects are only general. We tried to stick related people together, but there was the occasional oddball—and scheduling constraint—to deal with.)

Julie Downs, Carnegie Mellon University (suggested reading: Behavioral Response to Phishing Risk; Parents’ vaccination comprehension and decisions; The Psychology of Food Consumption), is a psychologist who studies how people make decisions, and talked about phishing. To determine how people respond to phishing attempts—what e-mails they open and when they click on links—she watched as people interacted with their e-mail. She found that most people’s strategies to deal with phishing attacks might have been effective 5-10 years ago, but are no longer sufficient now that phishers have adapted. She also found that educating people about phishing didn’t make them more effective at spotting phishing attempts, but made them more likely to be afraid of doing anything on line. She found this same overreaction among people who were recently the victims of phishing attacks, but again people were no better separating real e-mail from phishing attempts. What does make a difference is contextual understanding: how to parse a URL, how and why the scams happen, what SSL does and doesn’t do.

Jean Camp, Indiana University (suggested reading: Experimental Evaluation of Expert and Non-expert Computer Users’ Mental Models of Security Risks), studies people taking risks online. Four points: 1) “people create mental models from internal narratives about risk,” 2) “risk mitigating action is taken only if the risk is perceived as relevant,” 3) “contextualizing risk can show risks as relevant,” and 4) “narrative can increase desire and capacity to use security tools.” Stories matter: “people are willing to wash out their cat food cans and sweep up their sweet gum balls to be a good neighbor, but allow their computers to join zombie networks” because there’s a good story in the former and none in the latter. She presented two experiments to demonstrate this. One was a video experiment watching business majors try to install PGP. No one was successful: there was no narrative, and the mixed metaphor of physical and cryptographic “key” confused people.

Matt Blaze, University of Pennsylvania (his blog), talked about electronic voting machines and fraud. He related this anecdote about actual electronic voting machine vote fraud in Kentucky. In the question session, he speculated about the difficulty of having a security model that would have captured the problem, and how to know whether that model was complete enough.

Jeffrey Friedberg, Microsoft (suggested reading: Internet Fraud Battlefield; End to End Trust and the Trust User Experience; Testimony on “spyware”), discussed research at Microsoft around the Trust User Experience (TUX). He talked about the difficulty of verifying SSL certificates. Then he talked about how Microsoft added a “green bar” to signify trusted sites, and how people who learned to trust the green bar were fooled by “picture in picture attacks”: where a hostile site embedded a green-bar browser window in its page. Most people don’t understand that the information inside the browser window is arbitrary, but that the stuff around it is not. The user interface, user experience, mental models all matter. Designing and evaluating TUX is hard. From the questions: training doesn’t help much, because given a plausible story, people will do things counter to their training.

Stuart Schechter, Microsoft, presented this research on secret questions. Basically, secret questions don’t work. They’re easily guessable based on the most common answers; friends and relatives of people can easily predict unique answers; and people forget their answers. Even worse, the more memorable the question/answers are, the easier they are to guess. Having people write their own questions is no better: “What’s my blood type?” “How tall am I?”

Tyler Moore, Harvard University (suggested reading: The Consequences of Non-Cooperation in the Fight against Phishing; Information Security Economics—and Beyond), discussed his empirical studies on online crime and defense. Fraudsters are good at duping users, but they’re also effective at exploiting failures among IT professionals to perpetuate the infrastructure necessary to carry out these exploits on a large scale (hosting fake web pages, sending spam, laundering the profits via money mules, and so on). There is widespread refusal among the defenders to cooperate with each other, and attackers exploit these limitations. We are better at removing phishing websites than we are at defending against the money mules. Defenders tend to fix immediate problems, but not underlying problems.

In the discussion phase, there was a lot of talk about the relationships between websites, like banks, and users—and how that affects security for both good and bad. Jean Camp doesn’t want a relationship with her bank, because that unduly invests her in the bank. (Someone from the audience pointed out that, as a U.S. taxpayer, she is already invested in her bank.) Angela Sasse said that the correct metaphor is “rules of engagement,” rather than relationships.

Adam Shostack’s liveblogging. Ross Anderson’s liveblogging is in his blog post’s comments.

Matt Blaze is taping the sessions—except for the couple of presenters who would rather not be taped—I’ll post his links as soon as the files are online.

EDITED TO ADD (6/11): Audio of the session is here.

Posted on June 11, 2009 at 11:42 AM • View Comments

Obama's Cybersecurity Speech

I am optimistic about President Obama’s new cybersecurity policy and the appointment of a new “cybersecurity coordinator,” though much depends on the details. What we do know is that the threats are real, from identity theft to Chinese hacking to cyberwar.

His principles were all welcome—securing government networks, coordinating responses, working to secure the infrastructure in private hands (the power grid, the communications networks, and so on), although I think he’s overly optimistic that legislation won’t be required. I was especially heartened to hear his commitment to funding research. Much of the technology we currently use to secure cyberspace was developed from university research, and the more of it we finance today the more secure we’ll be in a decade.

Education is also vital, although sometimes I think my parents need more cybersecurity education than my grandchildren do. I also appreciate the president’s commitment to transparency and privacy, both of which are vital for security.

But the details matter. Centralizing security responsibilities has the downside of making security more brittle by instituting a single approach and a uniformity of thinking. Unless the new coordinator distributes responsibility, cybersecurity won’t improve.

As the administration moves forward on the plan, two principles should apply. One, security decisions need to be made as close to the problem as possible. Protecting networks should be done by people who understand those networks, and threats needs to be assessed by people close to the threats. But distributed responsibility has more risk, so oversight is vital.

Two, security coordination needs to happen at the highest level possible, whether that’s evaluating information about different threats, responding to an Internet worm or establishing guidelines for protecting personal information. The whole picture is larger than any single agency.

This essay originally appeared on The New York Times website, along with several others commenting on Obama’s speech. All the essays are worth reading, although I want to specifically quote James Bamford making an important point I’ve repeatedly made:

The history of White House czars is not a glorious one as anyone who has followed the rise and fall of the drug czars can tell. There is a lot of hype, a White House speech, and then things go back to normal. Power, the ability to cause change, depends primarily on who controls the money and who is closest to the president’s ear.

Because the new cyber czar will have neither a checkbook nor direct access to President Obama, the role will be more analogous to a traffic cop than a czar.

Gus Hosein wrote a good essay on the need for privacy:

Of course raising barriers around computer systems is certainly a good start. But when these systems are breached, our personal information is left vulnerable. Yet governments and companies are collecting more and more of our information.

The presumption should be that all data collected is vulnerable to abuse or theft. We should therefore collect only what is absolutely required.

As I said, they’re all worth reading. And here are some more links.

I wrote something similar in 2002 about the creation of the Department of Homeland Security:

The human body defends itself through overlapping security systems. It has a complex immune system specifically to fight disease, but disease fighting is also distributed throughout every organ and every cell. The body has all sorts of security systems, ranging from your skin to keep harmful things out of your body, to your liver filtering harmful things from your bloodstream, to the defenses in your digestive system. These systems all do their own thing in their own way. They overlap each other, and to a certain extent one can compensate when another fails. It might seem redundant and inefficient, but it’s more robust, reliable, and secure. You’re alive and reading this because of it.

EDITED TO ADD (6/2): Gene Spafford’s opinion.

EDITED TO ADD (6/4): Good commentary from Bob Blakley.

Posted on May 29, 2009 at 3:01 PM • View Comments

Kylin: New Chinese Operating System

Interesting:

China has developed more secure operating software for its tens of millions of computers and is already installing it on government and military systems, hoping to make Beijing’s networks impenetrable to U.S. military and intelligence agencies.

The secure operating system, known as Kylin, was disclosed to Congress during recent hearings that provided new details on how China’s government is preparing to wage cyberwarfare with the United States.

“We are in the early stages of a cyber arms race and need to respond accordingly,” said Kevin G. Coleman, a private security specialist who advises the government on cybersecurity. He discussed Kylin during a hearing of the U.S. China Economic and Security Review Commission on April 30.

The deployment of Kylin is significant, Mr. Coleman said, because the system has “hardened” key Chinese servers. U.S. offensive cyberwar capabilities have been focused on getting into Chinese government and military computers outfitted with less secure operating systems like those made by Microsoft Corp.

“This action also made our offensive cybercapabilities ineffective against them, given the cyberweapons were designed to be used against Linux, UNIX and Windows,” he said.

Is this real, or yet more cybersecurity hype pushed by agencies looking for funding and power? My guess is the latter. Anyone know?

Posted on May 18, 2009 at 6:06 AM • View Comments

Secure Version of Windows Created for the U.S. Air Force

I have long argued that the government should use its massive purchasing power to pressure software vendors to improve security. Seems like the U.S. Air Force has done just that:

The Air Force, on the verge of renegotiating its desktop-software contract with Microsoft, met with Ballmer and asked the company to deliver a secure configuration of Windows XP out of the box. That way, Air Force administrators wouldn’t have to spend time re-configuring, and the department would have uniform software across the board, making it easier to control and maintain patches.

Surprisingly, Microsoft quickly agreed to the plan, and Ballmer got personally involved in the project.

“He has half-a-dozen clients that he personally gets involved with, and he saw that this just made a lot of sense,” Gilligan said. “They had already done preliminary work themselves trying to identify what would be a more secure configuration. So we fine-tuned and added to that.”

The NSA got together with the National Institute of Standards and Technology, the Defense Information Systems Agency and the Center for Internet Security to decide what to lock down in the Air Force special edition.

Many of the changes were complex and technical, but Gilligan says one of the most important and simplest was an obvious fix to how Windows XP handled passwords. The Air Force insisted the system be configured so administrative passwords were unique, and different from general user passwords, preventing an average user from obtaining administrative privileges. Specifications were added to increase the length and complexity of passwords and expire them every 60 days.

It then took two years for the Air Force to catalog and test all the software applications on its networks against the new configuration to uncover conflicts. In some cases, where internally designed software interacted with Windows XP in an insecure way, they had to change the in-house software.

Now I want Microsoft to offer this configuration to everyone.

EDITED TO ADD (5/6): Microsoft responds:

Thanks for covering this topic, but unfortunately the reporter for the original article got a lot of the major facts, which you relied upon, wrong. For instance, there isn’t a special version of Windows for the Air Force. They use the same SKUs as everyone else. We didn’t deliver a special settings that only the Air Force can access. The Air Force asked us to help them to create a hardened gpos and images, which the AF could use as the standard image. We agreed to assist, as we do with any company that hires us to assist in setting their own security policy as implemented in Windows.

The work from the AF ended up morphing into the Federal Desktop Core Configuration (FDCC) recommendations maintained by NIST. There are differences, but they are essentially the same thing. NIST initially used even more secure settings in the hardening process (many of which have since been relaxed because of operational issues, and is now even closer to what the AF created).

Anyone can download the FDCC settings, documentation, and even complete images. I worked on the FDCC project for little over a year, and Aaron Margosis has been involved for many years, and continues to be involved. He offers all sorts of public knowledge and useful tools. Here, Aaron has written a couple of tools that anyone can use to apply FDCC settings to local group policy. It includes the source code, if anyone wants to customize them.

In the initial article, a lot of the other improvements, such as patching, came from the use of better tools (SCCM, etc.), and were not necessarily solely due to the changes in the base image (although that certainly didn’t hurt). So, it seems the author mixed up some of the different technology pushes and wrapped them up into a single story. He also seem to imply that this is something special and secret, but the truth is there is more openness with the FDCC program and the surrounding security outcomes than anything we’ve ever done before. Even better, there are huge agencies that have already gone first in trying to use these harden settings, and essentially been beta testers for the rest of the world. The FDCC settings may not be the best fit for every company, but it is a good model to compare against.

Let me know if you have any questions.

Roger A. Grimes, Security Architect, ACE Team, Microsoft

EDITED TO ADD (5/12): FDCC policy specs.

Posted on May 6, 2009 at 6:43 AM • View Comments

Who Should be in Charge of U.S. Cybersecurity?

U.S. government cybersecurity is an insecure mess, and fixing it is going to take considerable attention and resources. Trying to make sense of this, President Barack Obama ordered a 60-day review of government cybersecurity initiatives. Meanwhile, the U.S. House Subcommittee on Emerging Threats, Cybersecurity, Science and Technology is holding hearings on the same topic.

One of the areas of contention is who should be in charge. The FBI, DHS and DoD—specifically, the NSA—all have interests here. Earlier this month, Rod Beckström resigned from his position as director of the DHS’s National Cybersecurity Center, warning of a power grab by the NSA.

Putting national cybersecurity in the hands of the NSA is an incredibly bad idea. An entire parade of people, ranging from former FBI director Louis Freeh to Microsoft’s Trusted Computing Group Vice President and former Justice Department computer crime chief Scott Charney, have told Congress the same thing at this month’s hearings.

Cybersecurity isn’t a military problem, or even a government problem—it’s a universal problem. All networks, military, government, civilian and commercial, use the same computers, the same networking hardware, the same Internet protocols and the same software packages. We all are the targets of the same attack tools and tactics. It’s not even that government targets are somehow more important; these days, most of our nation’s critical IT infrastructure is in commercial hands. Government-sponsored Chinese hackers go after both military and civilian targets.

Some have said that the NSA should be in charge because it has specialized knowledge. Earlier this month, Director of National Intelligence Admiral Dennis Blair made this point, saying “There are some wizards out there at Ft. Meade who can do stuff.” That’s probably not true, but if it is, we’d better get them out of Ft. Meade as soon as possible—they’re doing the nation little good where they are now.

Not that government cybersecurity failings require any specialized wizardry to fix. GAO reports indicate that government problems include insufficient access controls, a lack of encryption where necessary, poor network management, failure to install patches, inadequate audit procedures, and incomplete or ineffective information security programs. These aren’t super-secret NSA-level security issues; these are the same managerial problems that every corporate CIO wrestles with.

We’ve all got the same problems, so solutions must be shared. If the government has any clever ideas to solve its cybersecurity problems, certainly a lot of us could benefit from those solutions. If it has an idea for improving network security, it should tell everyone. The best thing the government can do for cybersecurity world-wide is to use its buying power to improve the security of the IT products everyone uses. If it imposes significant security requirements on its IT vendors, those vendors will modify their products to meet those requirements. And those same products, now with improved security, will become available to all of us as the new standard.

Moreover, the NSA’s dual mission of providing security and conducting surveillance means it has an inherent conflict of interest in cybersecurity. Inside the NSA, this is called the “equities issue.” During the Cold War, it was easy; the NSA used its expertise to protect American military information and communications, and eavesdropped on Soviet information and communications. But what happens when both the good guys the NSA wants to protect, and the bad guys the NSA wants to eavesdrop on, use the same systems? They all use Microsoft Windows, Oracle databases, Internet email, and Skype. When the NSA finds a vulnerability in one of those systems, does it alert the manufacturer and fix it—making both the good guys and the bad guys more secure? Or does it keep quiet about the vulnerability and not tell anyone—making it easier to spy on the bad guys but also keeping the good guys insecure? Programs like the NSA’s warrantless wiretapping program have created additional vulnerabilities in our domestic telephone networks.

Testifying before Congress earlier this month, former DHS National Cyber Security division head Amit Yoran said “the intelligence community has always and will always prioritize its own collection efforts over the defensive and protection mission of our government’s and nation’s digital systems.”

Maybe the NSA could convince us that it’s putting cybersecurity first, but its culture of secrecy will mean that any decisions it makes will be suspect. Under current law, extended by the Bush administration’s extravagant invocation of the “state secrets” privilege when charged with statutory and constitutional violations, the NSA’s activities are not subject to any meaningful public oversight. And the NSA’s tradition of military secrecy makes it harder for it to coordinate with other government IT departments, most of which don’t have clearances, let alone coordinate with local law enforcement or the commercial sector.

We need transparent and accountable government processes, using commercial security products. We need government cybersecurity programs that improve security for everyone. The NSA certainly has an advisory and a coordination role in national cybersecurity, and perhaps a more supervisory role in DoD cybersecurity—both offensive and defensive—but it should not be in charge.

A version of this essay appeared on The Wall Street Journal website.

Posted on April 2, 2009 at 6:09 AM • View Comments

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Sidebar photo of Bruce Schneier by Joe MacInnis.