Research

One of the more difficult aspects of medical research is correlating treatments/actions with outcomes. This is a core principle of science based medicine (if you’ve never worked in the medical field, you might be shocked at the lack of science at the practitioner level). When performing medical studies the results aren’t always clean cut. There are practical and ethical limits to how certain studies can be performed, and organisms like people are so complex, living in an uncontrolled environment, that results are rarely cut and dried. Three categories of studies are: Pre-clinical/biological: lab research on cells, animals, or other subsystems to test the basic science. For example, exposing a single cell to a drug to assess the response. Experimental/clinical: a broad classification for studies where treatments are tested on patients with control groups, specific monitoring criteria, and attempts to control and monitor for environmental effects. The classic double blind study is an example. Observational studies: observing, without testing specific treatments. For example, observational studies show that autism rates have not increased over time by measuring autism rates of different age groups using a single diagnostic criteria. With rates holding steady at 1% for all living age groups, the conclusion is that while there is a perception of increasing autism, at most it’s an increase in diagnosis rates, likely due to greater awareness and testing for autism. No single class of study is typically definitive, so much of medicine is based on correlating multiple studies to draw conclusions. A drug that works in the lab might not work in a clinical study, or one showing positive results in a clinical study might fail to show desired long-term outcomes. For example, the press was recently full of stories that the latest research showed little to no improvement in long-term patent outcomes due to routine mammograms for patients without risk factors before the age of 50. When studies focus on the effectiveness of mammograms detecting early tumors, they show positive results. But these results do not correlate with improvements in long-term patient outcomes. Touchy stuff, but there are many studies all over medicine and other areas of science where positive research results don’t necessarily correlate with positive outcomes. We face the same situation with security, and the recent debate over password rotation highlights (see a post here at Securosis, Russell Thomas’s more-detailed analysis, and Pete Lindstrom’s take). Read through the comments and you will see that we have good tools to measure how easy or hard it is to crack a password based on how it was encrypted/hashed, length, use of dictionary words, and so on, but none of those necessarily predict or correlate with outcomes. None of that research answers the question, “How often does 90 day password rotation prevent an incident, or in what percentage of incidents did lack of password rotation lead to exploitation?” Technically, even those questions don’t relate to outcomes, since we aren’t assessing the damage associated with the exploitation (due to the lack of password rotation), which is what we’d all really like to know. When evaluating security, I think wherever possible we should focus on correlating, to the best of our ability, security controls with outcomes. Studies like the Verizon Data Breach Report are starting to improve our ability to draw these conclusions and make more informed risk assessments. This isn’t one of those “you’re doing it wrong” posts. I believe that we have generally lacked the right data to take this approach, but that’s quickly changing, and we should take full advantage of the opportunity. Share:

As you are already well aware (if not, see the announcement – we’ll wait), Google is now offering a free DNS resolver service. Before we get into the players, though, let’s first understand the reasons to use one of these free services. You’re obviously reading this blog post, and to get here your computer or upstream DNS cache resolved securosis.com to 209.240.81.67 – as long as that works, what’s the big deal? Why change anything? Most of you are probably reading this on a computer that dynamically obtains its IP address from the network you’re plugged into. It could be at work, home, or a Starbucks filled with entirely too much Christmas junk. Aside from assigning your own network address, whatever router you are connecting to also tells you where to look up addresses, so you can convert securosis.com to the actual IP address of the server. You never have to configuring your DNS resolver, but can rely on whatever the upstream router (or other DHCP server) tells you to use. For the most part this is fine, but there’s nothing that says the DNS resolver has to be accurate, and if it’s hacked it could be malicious. It might also be slow, unreliable, or vulnerable to certain kinds of attacks. Some resolvers actively mess with your traffic, such as ISPs that return a search pages filled with advertisements whenever you type in a bad address, instead of the expected error. If you’re on the road, your DNS resolver is normally assigned by whatever network you’re plugged into. At home, it’s your home router, which gets its upstream resolver from your ISP. At work, it’s… work. Work networks are generally safe, but aside from the reliability issues we know that home ISPs and public networks are prime targets for DNS attacks. Thus there are security, reliability, performance, and even privacy advantages to using a trustworthy service. Each of the more notable free providers cites its own advantages, along the lines of: Cache/speed – In this case a large cache should equate to a fast lookup. Since DNS is hierarchical in naturem if the immediate cache you’re asking to resolve a name already has the record you want, there is less wait to get the answer back. Maintaining the relevance and accuracy of this cache is part of what separates a good fast DNS service from, say, the not-very-well-maintained-DNS-service-from-your-ISP. Believe it or not, but depending on your ISP, a faster resolver might noticeably speed up your web browsing. Anycast/efficiency – This gets down into the network architecture weeds, but at a high level it means that when I am in Minnesota, traffic I send to a certain special IP address may end up at a server in Chicago, while traffic from Oregon to that same address may go to a server in California instead. Anycast is often used in DNS to provide faster lookups based on geolocation, user density, or any other metrics the network engineers choose, to improve speed and efficiency. Security – Since DNS is susceptible to many different attacks, it’s a common attack vector for things like create a denial-of-service on a domain name, or poisoning DNS results so users of a service (domain name) are redirected to a malicious site instead. There are many attacks, but the point is that if a vendor focuses on DNS as a service, they have probably invested more time and effort into protecting it than an ISP who regards DNS as simply a minor cost of doing business. These are just a few reasons you might want to switch to a dedicated DNS resolver. While there are a bunch of them out there, here are three major services, each offering something slightly different: OpenDNS: One of the most full featured DNS resolution services, OpenDNS offers multiple plans to suit your needs – basic is free. The thing that sets OpenDNS apart from the others is their dashboard, from which you can change how the service responds to your networks. This adds flexibility, with the ability to enable and disable features such as content filtering, phishing/botnet/malware protection, reporting, logging, and personalized shortcuts. This enables DNS to serve as a security feature, as the resolver can redirect you someplace safe if you enter the wrong address; you can also filter content in different categories. The one thing that OpenDNS often gets a bad rap for, however, is DNS redirection on non-existent domains. Like many ISPs, OpenDNS treats every failed lookup as an opportunity to redirect you to a search page with advertisements. Since many other applications (Twitter clients, Skype, VPN, online gaming, etc…) use DNS, if you are using OpenDNS with the standard configuration you could potentially leak login credentials to the network, as a bad request will fail to get back a standard NXDOMAIN response. This can result in sending authentication credentials to OpenDNS, as your confused client software sees the response as a successful NOERROR and proceeds, rather than aborting as it would if it got back the ‘proper’ NXDOMAIN. You can disable this behavior, but doing so forfeits some of the advertised features that rely on it. OpenDNS is a great option for home users who want all the free security protection they can get, as well as for organizations interested in outsourcing DNS security and gaining a level of control and insight that might otherwise be available only through on-site hardware. Until your kid figures out how to set up their own DNS, you can use it to keep them from visiting porn sites. Not that your kid would ever do that. DNSResolvers: A simple no-frills DNS resolution service. All they do is resolve addresses – no filtering, redirection, or other games. This straight up DNS resolution service also won’t filter for security (phishing/botnet/malware). DNSResolvers is a great fast service for people who want well-maintained resolvers and are handling security themselves. DNSResolvers effectively serves as an ad demonstrating the competence and usefulness of parent company easyDNS), by providing a great free DNS service, which encourages some users