Broken Trust Part 1: Reflections on RSA's SecurID

Monday, June 20, 2011

Enno Rey

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Broken Trust Part 1: Definitions & Fundamentals + Some More Reflections on RSA

This again is going to be a little series of posts. Their main topic – next to the usual deviations & ranting I tend to include in blog posts – is some discussion of “trust” and putting this discussion into the context of recent events and future developments in the infosec space.

The title originates from a conversation between Angus Blitter and me in a nice Thai restaurant in Zurich where we figured the consequences of the latest RSA revelations.

While we both expect that – unfortunately – not much is really going to happen (surprisingly many people, including some CSOs we know, are still trying to somehow downplay this or sweep it under the carpet, shying away from the – obvious – consequences it might have to accept that for a number of environments RSA SecurID is potentially reduced to single factor auth nowadays…), the long term impact on our understanding of 3rd party (e.g. vendor) trust might be more interesting. Furthermore “Broken Trust” seems a promising title for a talk at upcoming Day-Con V… 

Before getting into too much detail too early I’d like to outline the model of trust, control and confidence we use at ERNW. This model was originally based on Piotr Cofta’s seminal book on “Trust, Complexity and Control: Confidence in a Convergent World” and Rino Falcone’s & Christiano Castelfranchi’s paper “Trust and Control: A Dialectic Link” and has evolved a bit in the last two years. Let’s start with some

Definitions

Despite (or maybe due to) being an apparently essential part of human nature and a fundamental factor of our relationships and societies there is no single, concise definition of “trust”. Quite some researchers discussing trust related topics do not define the term at all and presume some “natural language” understanding.

This is even more true in papers in the area of computer science (CS) and related fields, the most prominent example being probably Ken Thompson’s ” Reflections on Trusting Trust” where no definition is provided at all. Given the character and purpose of RFCs in general and their relevance for computer networks it seems an obvious course of action to look for an RFC providing a clarification. In fact the RFC 2828 defines as follows:

“Trust [...] Information system usage: The extent to which someone who relies on a system can have confidence that the system meets its specifications, i.e., that the system does what it claims to do and does not perform unwanted functions”

which is usually shortened to statements like “trust = system[s] perform[s] as expected”. We don’t like this definition for a number of reasons (outside the scope of a blog post) and prefer the definition the Italian sociologist Diego Gambetta published in his paper “Can we trust trust?” in 1988 (and which has – while originating from another discipline – gained quite some adoption in CS) that states

“Trust (or, symmetrically, distrust) is a particular level of the subjective probability with which an agent assesses that another agent or group of agents will perform a particular action, both before he can monitor such action (or independently of his capacity ever to be able to monitor it) and in a context in which it affects his own action.”

With Falcone & Castelfranchi we define control as “a (meta) action:

a) Aimed at ascertaining whether another action has been successfully executed or if a given state of the world has been realized or maintained […]

b) aimed at dealing with the possible deviations and unforeseen events in order to positively cope with them (intervention).”

It should be noted that the term “control” is used here with a much broader sense (thus the attribute “meta” in the above definition) than in some information security standard documents (e.g. the ISO 27000 family) where control is defined as a “means of managing risk, including policies, procedures, guidelines, practices or organizational structures, which can be of administrative, technical, management, or legal nature.” [ISO27002, section 2.2]

Following Cofta’s model both, trust and control, constitute ways to build confidence which he defines as:

“One’s subjective probability of expectation that a certain desired event will happen (or that the undesired one will not happen), if the course of action is believed to depend on another agent”.

[I know that this sounds quite similar to Gambetta's definition of trust but I will skip discussing such subtleties for the moment, in this post.]

Putting the elements together & bringing the whole stuff to the infosec world

Let’s face it: in the end of the day all the efforts we as security practitioners take ultimately serve a simple goal, that is somebody (be it yourself, your boss or some CxO of your organization) reaching a point where she states “considering the relevant risks and our limited resources, we’ve done what is humanly possible”. Or just “it’s ok the way it is. I can sleep well now”.

I’m well aware that this may sound strange to some readers still believing in a “concrete, concise and measurable approach to information security” but this is the reality in most organizations. And the mentioned point of “it’s ok” reflects fairly precisely the above definition of confidence (with the whole of events threatening the security of an environment being “another agent”).

Now, this state of confidence can be attained on two roads, that of “control” (applying security controls and, having done so, subsequently sleeping well) or that of “trust” (reflecting on some elements of the overall picture and then refraining from the application of certain security controls, still sleeping well).

A simple example might help to understand the difference: imagine you move to a new house in another part of the world. Your family is set to arrive one week later, so you have some days left to create an environment you consider “to be safe enough” for them.

What would you do (to reach the state of confidence)? I regularly ask this question in workshops I give and the most common answers go like “install [or check] the doors & locks”, “buy a dog”, “install an alarm system”.

These are typical responses for “technology driven people” and the last one, sorry guys, is – as of my humble opinion – a particularly dull one given this is a detective/reactive type of control requiring lots of the most expensive operational resource, that is human brain (namely for follow-up on alarms = incident response). Which, btw, is the very reason why it pretty much never works in a satisfying manner, in pretty much any organization.

And yes, I understand that naming this regrettable reality is against the current vogue of “you’ll get owned anyway – uh, uh APT is around – so you need elaborate detection capabilities. just sign here for our new fancy SIEM/deep packet inspection appliance/deep inspection packet appliance/revolutionary network monitoring platform” BS.

Back to our initial topic (I announced some ranting, didn’t I? All this stuff (doors & locks, the dog, the alarm system) follow the “control approach” and, more importantly and often overlooked, they all might require quite some operational effort (key management for the doors – don’t underestimate this, especially if you have a household full of kids, walking the dog, tuning the alarm system & as stated above: resolving the incidents one it goes off, etc.).

Another approach – at least for some threats, to some assets – could be to find out which parties are involved in the overall picture (the neighbors, the utility providers, the legal authorities and so on) and then, maybe, deciding “in this environment we have trust in (some of) those and that’s why we don’t need the full set of potential controls”. Living in a hamlet with about 40 inhabitants, in the Bavarian country side, I can tell you that the handling of doors and locks there certainly is a different one than in most European metropolises…

Some of you might argue here “nice for you, Enno, but what’s the application in corporate information security space?”. Actually that’s an easy one. Just think about it:

- Do you encrypt the MPLS links connecting your organization’s main sites? [Most of you don't, because "we trust our carriers". Which can be a entirely reasonable security decision, depending on your carriers... and their partners... and the partners of their partners...]

- Do you perform full database encryption for your ERP systems hosted & operated by some outsourcing provider? [Most of you don't, trusting that provider, which again might be a fully legitimate and reasonable approach].

- Did you ever ask the company providing essential parts of your authentication infrastructure if they kept copies of your key material and, more importantly, if they did so in a sufficiently secure way? [Most of you didn't, relying on reputation-based trust "everybody uses them, and aren't they the inventors of that algorithm widely used for banking transactions? and isn't 'the military' using this stuff, too?" or so].

So, in short: trust is a confidence-contributing element and common security instrument in all environments and – here comes the relevant message – this is fully ok. As efficient information security work (leading to confidence) relies on both approaches: trust (where justified) and control (where needed). Alas most infosec people still have a control-driven mindset, not recognizing the value of trust. [this will have to change radically in "the age of the cloud", more on this in a later part of this series].

Unfortunately, both approaches (trust & control) have their own respective shortcomings:

- following the control road usually leads to increased operational cost & complexity and might have severe business impact.

- trust, by it’s very nature (see the “Gambetta definition” above) is something “subjective” and thereby might not be suited to base corporate security decisions on

BUT – and I’m finally getting to the main point of this post – if we could transform “subjective trust” into the documented and justified, it might become a valuable and accepted element in an organization’s infosec governance process [and, again, this will have to happen anyway, as in the age of the cloud, the control approach is doomed.

And pls don't try to tell me the "we'll audit our cloud providers then" story. ever tried to negotiate with $YOUR_FAVORITE_IAAS_PROVIDER on data center visits or just very basic security reporting or sth.?].

Still, then the question is: What could that those “reasons for trust” be?

Evaluating trust(worthiness) in a structured way

There are various approaches to evaluate factors that contribute to the trustworthiness of another party (called “trustee” in the following) and hence their own (the “trustor’s”) trust towards that party. For example, Cofta lists three main elements, that are (the associated questions in brackets are paraphrases by myself):

  • Continuity (“How long will we work together?”)
  • Competence (“Can $TRUSTEE provide what we expect?”)
  • Motivation (“What’s $TRUSTEE’s motivation?”)

We, however, usually prefer the avenue the ISECOM uses for their Certified Trust Analyst training which is roughly laid out here. It’s based on ten trust properties, two of which are not aligned with our/Gambetta’s definition of trust and are thereby omitted (these two are “control” and “offsets”, for obvious reasons. Negotiating a compensation to be paid when the trust is broken constitutes the exact opposite of trust… it can contribute to confidence, but not to trust in the above sense). So there’s eight left and these are:

  • Size (“Who exactly are you going to trust?”. In quite some cases this might be an interesting question. Think of carriers partnering with others in areas of the world called “emerging markets” or just think of RSA and its shareholders. And this is why background checks are performed when you apply for a job in some agency; they want to find out who you interact with in your daily life and who/what might influence your decisions.).
  • Symmetry (“Do they trust us?”. This again is an interesting, yet often neglected, point. I first stumbled across this when performing an MPLS carrier evaluation back in 2007).
  • Transparency (“How much do we know about $TRUSTEE?”).
  • Consistency (“What happened in the past?”. This is the exact reason why to-be-employers ask for criminal records of the to-be-employees.).
  • Integrity (“[How] Do we notice if $TRUSTEE changes?”).
  • Value of Reward (“What do we gain by trusting?” If this one has enough weight, all the others might become irrelevant. Which is exactly the mechanism Ponzi schemes are based upon. Or your CIO’s decision “to go to the cloud within the next six months” – overlooking that the departments are already extensively using AWS, “for demo systems” only, of course – or, for that matter, her (your CIO’s decision) to virtualize highly classified systems by means of VMware products. See also this post of Chris Hoff on “the CxO part in the game”.).
  • Components: (“Which resources does $TRUSTEE rely on?”).
  • Porosity (“How separated is $TRUSTEE from it’s environment?”).

Asking all these questions might either help to get a better understanding who to trust & why and thereby contribute to well-informed decision taking or might at least help to identify the areas where additional controls are needed (e.g. asking for enhanced reporting to be put into the contracts).

Applying this stuff to the RSA case

So, what does all this mean when reflecting on the RSA break-in? Why exactly is RSA’s trustworthiness potentially so heavily damaged?

As a little exercise, let’s just pick some of the above questions and try to figure the respective responses. Like I did in this post three days after RSA filed the 8-K report I will leave potential conclusions to the valued reader…

Here we go:

“Size”, so who exactly are you trusting when trusting “RSA, The Security Division of EMC”? Honestly, I do not know much about RSA’s share- and stake-holders. Still, even though not regarding myself as particularly prone to conspiracy theories, I think that Sachar Paulus, the Ex-CSO of SAP and now a professor for Corporate Security and Risk Management at the University of Applied Sciences Brandenburg, made some interesting observations in this blogpost.

“Symmetry” (do they trust us?): everybody who had the dubious pleasure to participate in one of those – hilarious – conference calls RSA held with large customers after the initial announcement in late March, going like:

  • “no customer data was compromised.”
  • “what do you mean, do you mean no seed files where compromised?”
  • “as we stated, no customer data, that is PII was compromised.”
  • “so what about the seeds?”
  • “as we just said, no customer data was compromised.”
  • “and what about the seeds?”
  • “we can’t comment on this further due to the ongoing investigation. but we can assure you no customer data was compromised.”
  • might think of an answer on his/her own…

“Transparency”: well, see above. One might add: “did they ever tell you they kept a copy of your seed files?” but, hey, you never asked them, did you? I mean, even the (US …) defense contractors use this stuff, so why should one have asked such silly questions…

“Integrity”, which the ISECOM defines as “the amount and timely notice of change within the target”. Well… do I really have to comment on “the amount [of information]” and “timely notice” RSA delivered in the last weeks & months?  Some people assume we might never have known of the break-in if they’d not been obliged to file a 8-K form (as standard breach-laws might not have kicked in, given – remember – “no customer data was exposed”…) and there’s speculation we might never have known that actually the seeds were compromised if the Lockheed Martin break-in hadn’t happened. I mean, most of us were pretty sure it _was_ about the seed files, but of course, it’s easy to say so in hindsight.

“Components” and “porosity”: see above.

Conclusions

If you have been wondering “why do my guts tell me we shouldn’t trust these guys anymore?” this post might serve as a little contribution to answering this question in a structured way. Furthermore the intent was to provide some introduction to the wonderful world of trust, control and confidence and its application in the infosec world. Stay tuned for more stuff to come in this series.

Cross-posted from Insinuator

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