An Inspiring Phone Call

Last night, I received a phone call from a neighbor asking if he should renew his home anti-virus subscription.  I typically shy away from giving people advice on this sort of question, but it did give me pause and caused me to do some thinking before I answered him.

I thought about how in most large enterprises that I advise, anti-virus is <25% effective at detecting malicious code threats.  Worse yet, most anti-virus vendors have not only sold large enterprises software that is largely ineffective, but they have also sold those enterprises on a mantra/workflow/philosophy that is nearly useless.  In other words, most anti-virus vendors will suggest that you review their logs regularly to identify systems infected with malicious code.  I remember from graduate school that this is, by definition, the quintessential biased sample.  In other words, since anti-virus is <25% effective at detecting and identifying threats, the enterprise is left with a gaping hole/blind spot of >75%.  Stated another way, if you trust anti-virus logs to guide your analysis, workflow, and/or process, you will be left largely in the dark.

The "Know Your Network" philosophy discussed in this blog and elsewhere is really the only way to effectively monitor a large, enterprise network.  Unfortunately, anti-virus vendors do not seem to be interested in improving through novel or cutting edge techniques.  They are quite content to sell both home users and enterprises the 21st century equivalent of a bridge.

Of course, anti-virus logs are somewhat useful as a supporting/corroborating data source for investigations that begin with true network forensics/network traffic analysis, but not much else.  In other words, anti-virus logs can tell you if the malicious code that you see a user downloading in the proxy logs or via deep packet inspection (DPI) data was somehow detected and cleaned by anti-virus.  As an aside, even this is not 100% reliable though, as it is not uncommon for malicious code infection vectors to try several different exploits and/or executable downloads.  Just because anti-virus caught one of them, doesn't mean it caught all of them.  The analyst still needs to examine the proxy logs, firewall logs, DPI data, and/or any other relevant data looking for artifacts of infection.

So back to my neighbor.  After thinking about this for a moment, I explained to him that the anti-virus vendor he was thinking of sending additional money to was really no more effective than some of the free products that are available.  I advised him to hold onto his money.  After all, if one ignores the hype and thinks about it logically, it only makes sense.

Passive DNS Expansion

Recently, I learned that an analytical method I had experimented with a while back was being used by an organization to generate intelligence.  It would have been nice to have been given proper credit, but regardless, it's still great that the method is in use.  I've called the method "Passive DNS Expansion" for lack of a better term.  The basic idea is that you use a combination of forward DNS resolution and passive DNS data to generate lists of malicious domain names that can be used for analysis and/or network defense purposes.  It turns out to be a pretty handy way to generate some actionable intelligence.  The basic algorithm is as follows:

1) Begin with a known malicious domain name
2) Forward resolve the known malicious domain name and obtain its current IP address
3) Leverage passive DNS data to identify the domain's IP address history
4) Search passive DNS data for the IP addresses to obtain a list of domain names associated with those IP addresses
5) Perform some cursory research on the domain names to determine whether or not they can be reliably used for analysis/network defense

I'd like to illustrate this with an example.  I picked the domain name at the top of the Zeus Tracker list this morning to use as an example for illustrative purposes:

1) I begin with the domain name freetop[.]mobi, which I obtained from the Zeus Tracker list
2) The domain name forward resolves to 69[.]175[.]127[.]82
3) Passive DNS data shows only one IP address for this domain: 69[.]175[.]127[.]82
4) In this case, there is only one additional domain name associated with this IP address in passive DNS data: mymobilewap[.]info
5) A Google search for mymobilewap[.]info indicates that the domain name is most likely malicious and could probably be used reliably for network traffic analysis purposes.


I'm a big fan of this method.  In the past, I've scripted these steps to automate the process with positive results.  Feel free to give it a try and let me know your thoughts!

Cyber Is Not A Hill

Of late, I've heard a lot from military minded people about running "cyber security and cyber operations" (whatever that means) like you would run a physical world military operation.  In other words, I hear a lot of discussion about running a cyber operation like you would run an operation to take a hill (land), drop a bomb (air), or secure a strait (sea).  This seems to be a foregone conclusion that is not up for debate.  Unfortunately, I don't see how it's possible to run cyber security and cyber operations in this manner.  In other words, the enemy in cyber is one that I can't see, can't react as fast as, and am not as smart as.  I can't outspend this enemy, and the enemy has just as much "history" and "experience" as I do.  The enemy does not have to follow bureaucratic processes and/or laws, and the enemy is free to recruit the cream of the crop without needing them to adhere to arcane standards that are irrelevant to the cyber landscape.  So, all in all, how is a large, hulking bureaucracy designed for and experienced in other purposes supposed to fight this enemy?

They're not.  Perhaps that's why I've seen a lot of discussion to date, but little progress.  Everyone seems to be a cyber expert of late (experts follow the money I suppose), but most of these so-called experts have never worked in the space, even for a short while.  If cyber security is indeed to be treated like a battle, the enemy has already infiltrated us and is living within us.  Talk is cheap.  Action is rare, sorely needed, and often winds up stalled in the headstrong trade winds that often dominate bureaucracies.  I would urge those skilled in the physical world's battle strategies (these are often the people in leadership positions these days) to keep an open mind and choose progress and success over tradition and procedure.  It may necessitate listening to people who have little or no military experience and may look or act differently than you would expect.  It may also necessitate being open to the fact that we, as a society, may not know how to approach the cyber landscape, and that approaching it as a military operation may be entirely misguided.  Otherwise, I fear we may end up in a bad place.

I've had experience consulting in both the public sector and the private sector.  What's amazing to me is that although private sector organizations often start out with their capabilities behind those of similarly sized public sector organizations, they are soon able to catch up and surpass their public sector peers.  It isn't voodoo or magic that is responsible for this transformation -- it's openness, discipline, competency, and most importantly, the choice of progress over politics, pomp, and circumstance..

Following The Trail Of DNS

As discussed previously on this blog, logging and subsequently monitoring/analyzing DNS traffic is extremely important.  It sounds straightforward, but it can often be challenging to accomplish this in an enterprise.  This is likely the reason why most enterprises I encounter, unfortunately, don't log DNS traffic.

Here are a few issues that enterprises often encounter:

1) The volume of DNS traffic in an enterprise is overwhelming.  If you think about it, almost every network transaction requires at least one, and often times multiple domain name look ups to function properly.  This generates an incredible amount of traffic when you consider that there may be several hundred thousand machines generating several billion network transactions per day on a typical enterprise network.  Keeping even 30, 60, or 90 days worth of this data can quickly inundate an organization.

2) DNS functions in a "nested" fashion within an enterprise.  Many enterprises use Active Directory Domain Controllers, or some other nested means by which to resolve domain names.  This creates multiple layers of "NATing"/"client abstraction" issues that both necessitates multiple layers of DNS logging (often redundant), and creates the need to "following the trail" of DNS transactions through the network.  An easy fix to this issue is to mandate that all client endpoints resolve DNS in one logical place.  Note that one logical place for logging purposes can translate into an array of physical systems for redundancy and availability reasons.  I'm not trying to introduce a single point of failure here, but rather a single point of success.

3) Most DNS logging doesn't "match up" or sessionize requests with their corresponding responses (or lack thereof).  This leads to 2 problems.  First, nearly twice as much data is generated as is really necessary.  Instead of just one line in the logging with the DNS request and its corresponding response(s) (or lack thereof), there are two or more lines in the logging.  Most of the information in the additional lines is redundant, with only a small amount of that information being new and/or adding value.

4) Because the information contained in the DNS logging is not sessionized, it is incumbent on the analyst to "match up" the requests with their corresponding response(s) (or lack thereof).  It isn't always obvious how best to do this, and in some cases, the logging is such that it's almost impossible to do this.  This introduces a needless level of complexity and concern that often acts as a barrier to enterprises adopting the policy of logging DNS traffic.

If I look at the four challenges explained above, I believe that one solution could potentially abate and/or solve many of the issues presented by these challenges.  To me, a sessionized, intelligently aggregated DNS logging ability could produce a compact, efficient data source for retention, analysis, and monitoring within an enterprise.  To those of you familiar with my blog and/or my way of thinking, this may sound a lot like a specialized version of layer 7 enriched network flow data and/or the uber data source.  Indeed it is.  Indeed it is.

Thinking About Vectors

I find it interesting how most clients ask me to help them write reports or alerts to monitor their enterprises for various different threats. This is, of course, to be expected in my line of work. What I often ask them is "What vectors into (and out of) the enterprise are you concerned with/do you want to monitor for?" Clients often find this to be a surprising question, but when you think about it, the question isn't really all that surprising. The most advanced analytic, the fanciest report, or the coolest detection technique aren't worth much if they aren't relevant to the enterprise they're being applied to, right? It's important to conceptualize and understand what it is you'd like to monitor for based on the vectors into (and out of) the enterprise you're concerned with. Once that is done, implementing those concepts is usually fairly straightforward. That's all well and good, but what if you don't know what vectors you ought to be concerned with? To that, I say, know your network! Study and analyze the data transiting the network and let it guide you towards an understanding of the vectors you might want to concern yourself with.

Boiling The Ocean

Boiling the ocean is one of my favorite phrases. As the phrase connotes, boiling the ocean is a process that will likely never converge to success, nor end. I am reminded of this phrase as I attend FloCon this week. The vast majority of people I work with professionally understand the need to make compromises and accept some imperfections in order to make progress operationally. In my experience, operational progress, though often imperfect, still leads to improved network security monitoring and security operations in infinitely more cases than taking a "boil the ocean" approach. In other words, an 80% solution at least gets you 80% of what you want and need, while waiting for everything to be 100% perfect will always get you nowhere. There are a few in attendance at FloCon for whom the compromises that operational personnel must make is lost on them. I can't think of a way to show them the other side, other than to put them in an operational environment for a year (or perhaps longer)....

And Then What?

I am at FloCon this week and enjoying the conference tremendously. I always enjoy FloCon, as it's a unique opportunity to catch up with peers in the community. It's also a great place to learn about different techniques and methods that people are using to analyze network security data. There was a presentation this morning from US-CERT that discussed some interesting analytical work US-CERT is currently doing. The presentation described some of the architecture, systems, processes, and procedures that US-CERT is using to perform analysis of various different types of data. The presentation was interesting, but it made me ask the question, "and then what?". All that analysis is great, but at the end of the day practitioners (like myself) need actionable intelligence and information that we can use to defend the networks we are responsible for. Unfortunately, we're not getting much in the way of actionable information and intelligence from US-CERT. As our national CERT, this is disappointing. My intention here is not to pick on or harass the analysts who work hard in service of our nation day in and day out. Rather, I'm hoping that the leadership in our government, and particularly the leadership within DHS will get a clue sometime soon. If I had a minute with the leadership I would ask them why they can't find some way to cut through the bureaucratic red tape and share information with a nation (and world) so desparate for it. After all, the security of our nation's most critical infrastructure depends on it, right? Analysis is great, but I am reminded this morning that analysis is not for analysis' sake. Analysis should serve some productive end, namely producing actionable information and intelligence for those who so desperately need it. Come on DHS -- get with the program.