Tag: audit

Enarx for everyone (a quest)

In your backpack, the only tool that you have to protect you is Enarx…

You are stuck in a deep, dark wood, with spooky noises and roots that seem to move and trip you up.  Behind every tree malevolent eyes look out at you.  You look in your backpack and realise that the only tool that you have for your protection is Enarx, the trusty open source project given you by the wizened old person at the beginning of your quest.  Hard as you try, you can’t remember what it does, or how to use it.  You realise that now is that time to find out.

What do you do next?

  • If you are a business person, go to 1. Why I need Enarx to reduce business risk.
  • If you are an architect, go to 2. How I can use Enarx to protect sensitive data.
  • If you are a techy, go to 3. Tell me more about Enarx technology (I can take it).

1. Why I need Enarx to reduce business risk

You are the wise head upon which your business relies to consider and manage risk.  One of the problems that you run into is that you have sensitive data that needs to be protected.  Financial data, customer data, legal data, payroll data: it’s all at risk of compromise if it’s not adequately protected.  Who can you trust, however?  You want to be able to use public clouds, but the risks of keeping and processing information on systems which are not under your direct control are many and difficult to quantify.  Even your own systems are vulnerable to outdated patches, insider attacks or compromises: confidentiality is difficult to ensure, but vital to your business.

Enarx is a project which allows you to run applications in the public cloud, on your premises – or wherever else – with significantly reduced and better quantifiable risk.  It uses hardware-based security called “Trust Execution Environments” from CPU manufacturers, and cuts out many of the layers that can be compromised.  The only components that do need to be trusted are fully open source software, which means that they can be examined and audited by industry experts and your own teams.

Well done: you found out about Enarx.  Continue to 6. Well, what’s next?

2. How I can use Enarx to protect sensitive data

You are the expert architect who has to consider the best technologies and approaches for your organisation.  You worry about where best to deploy sensitive applications and data, given the number of layers in the stack that may have been compromised, and the number of entities – human and machine – that have the opportunity to peek into or mess with the integrity of your applications.  You can’t control the public cloud, nor know exactly what the stack it’s running is, but equally, the resources required to ensure that you can run sufficient numbers of hardened systems on premises are growing.

Enarx is an open source project which uses TEEs (Trusted Execution Environments), to allow you to run applications within “Keeps” on systems that you don’t trust.  Enarx manages the creation of these Keeps, providing cryptographic confidence that the Keeps are using valid CPU hardware and then encrypting and provisioning your applications and data to the Keep using one-time cryptographic keys.  Your applications run without any of the layers in the stack (e.g. hypervisor, kernel, user-space, middleware) being able to look into the Keep.  The Keep’s run-time can accept applications written in many different languages, including Rust, C, C++, C#, Go, Java, Python and Haskell.  It allows you to run on TEEs from various CPU manufacturers without having to worry about portability: Enarx manages that for you, along with attestation and deployment.

Well done: you found out about Enarx.  Continue to 6. Well, what’s next?

3. Tell me more about Enarx technology (I can take it)

You are a wily developer with technical skills beyond the ken of most of your peers.  A quick look at the github pages tells you more: Enarx is an open source project to allow you to deploy and applications within TEEs (Trusted Execution Environments).

  • If you’d like to learn about how to use Enarx, proceed to 4. I want to use Enarx.
  • If you’d like to learn about contributing to the Enarx project, proceed to 5. I want to contribute to Enarx.

Well done: you found out about Enarx.  Continue to 6. Well, what’s next?

4. I want to use Enarx

You learn good news: Enarx is designed to be easy to use!

If you want to run applications that process sensitive data, or which implement sensitive algorithms themselves, Enarx is for you.  Enarx is a deployment framework for applications, rather than a development framework.  What this means is that you don’t have to write to particular SDKs, or manage the tricky attestation steps required to use TEEs.  You write your application in your favourite language, and as long as it has WebAssembly as a compile target, it should run within an Enarx “Keep”.  Enarx even manages portability across hardware platforms, so you don’t need to worry about that, either.  It’s all open source, so you can look at it yourself, audit it, or even contribute (if you’re interested in that, you might want to proceed to 5. I want to contribute to Enarx).

Well done: you found out about Enarx.  Continue to 6. Well, what’s next?

5. I want to contribute to Enarx

Enarx is an open source project (under the Apache 2.0 licence), and we welcome contributions, whether you are a developer, tester, documentation guru or other enthusiastic bod with an interest in providing a way for the rest of the world to up the security level of the applications they’re running with minimal effort.  There are various components to Enarx, including attestation, hypervisor work, uni-kernel and WebAssembly run-time pieces.  We want to provide a simple and flexible framework to allow developers and operations folks to deploy applications to TEEs on any supported platform without recompilation, having to choose an obscure language or write to a particular SDK.  Please have a look around our github site and get in touch if you’re in a position to contribute.

Well done: you found out about Enarx.  Continue to 6. Well, what’s next?

6. Well, what’s next?

You now know enough to understand how Enarx can help you: well done!  At time of writing, Enarx is still in development, but we’re working hard to make it available to all.

We’ve known for a long time that we need encryption for data at rest and in transit: Enarx helps you do encryption for data in use.

For more information, you may wish to visit:

Why security policies are worthless

A policy, to have any utility at all, needs to exist in a larger context.

“We need a policy on that.” This is a phrase that seems to act as a universal panacea to too many managers. When a problem is identified, and the blame game has been exhausted, the way to sort things out, they believe, is to create a policy. If you’ve got a policy, then everything will be fine, because everything will be clear, and everyone will obey the policy, and nothing can go wrong.

Right[1].

The problem is that policy, on its own, is worthless.

A policy, to have any utility at all, needs to exist in a larger context, or, to think of it in a different way, to sit in a chain of artefacts.  It is its place in this chain that actually gives it meaning.  Let me explain.

When that manager said that they wanted a policy, what did that actually mean?  That rather depends on how wise the manager is[2].  Hopefully, the reason that the manager identified the need for a policy was because:

  1. they noticed that something had gone wrong that shouldn’t have done and;
  2. they wanted to have a way to make sure it didn’t happen again.

The problem with policy on its own is that it doesn’t actually help with either of those points.  What use does it have, then?

Governance

Let’s look at those pieces separately.  When we say that “something had gone wrong that shouldn’t have done“, what we’re saying is that there is some sort of model for what the world should look like, giving us often general advice on our preferred state.  Sometimes this is a legal framework, sometimes it’s a regulatory framework, and sometimes it’s a looser governance model.  The sort of thing I’d expect to see at this level would be statements like:

  • patient data must be secured against theft;
  • details of unannounced mergers must not be made available to employees who are not directors of the company;
  • only authorised persons may access the military base[4].

These are high level requirements, and are statements of intent.  They don’t tell you what to do in order to make these things happen (or not happen), they just tell you that you have to do them (or not do them).  I’m going to call collections of these types of requirements “governance models”.

Processes

At the other end of the spectrum, you’ve got the actual processes (in the broader sense of the term) required to make the general intent happen.  For the examples above, these might include:

  • AES-256 encryption using OpenSSL version 1.1.1 FIPS[5], with key patient-sym-current for all data on database patients-20162019;
  • documents Indigo-1, Indigo-3, Indigo-4 to be collected after meeting and locked in cabinet Socrates by CEO or CFO;
  • guards on duty at post Alpha must report any expired passes to the base commander and refuse entry to all those producing them.

These are concrete processes that must be followed, which will hopefully allow the statements of intent that we noted above to be carried out.

Policies and audit

The problem with both the governance statements and the processes identified is that they’re both insufficient.  The governance statements don’t tell you how to do what needs to be done, and the processes are context-less, which means that you can’t tell what they relate to, or how they’re helping.  It’s also difficult to know what to do if they fail: what happens, for example, if the base commander turns up with an expired pass?

Policies are what sit in the middle.  They provide guidance as to how to implement the governance model, and provide context for the processes.  They should give you enough detail to cover all eventualities, even if that’s to say “consult the Legal Department when unsure[6]”.  What’s more, they should be auditable.  If you can’t audit your security measures, then how can you be sure that your governance model is being followed?  But governance models, as we’ve already discovered, are at the level of intent – not the sort of thing that can be audited.

Policies, then, should provide enough detail that they can be auditable, but they should also preferably be separated enough from implementation that rules can be written that are applicable in different circumstances.  Here are a few policies that we might create to follow the first governance model examples above:

  • patient data must be secured against theft;
    • Policy 1: all data at rest must be encrypted by a symmetric key of at least 256 bits or equivalent;
    • Policy 2: all storage keys must be rotated at least once a month;
    • Policy 3: in the event of a suspected key compromise, all keys at the same level in that department must be rotated.

You can argue that these policies are too detailed, or you can argue that they’re not detailed enough: both arguments are fair, and level of detail (or granularity) should depend on the context and the use to which they are being put.  However, though I’m sure that all of the example policies I’ve given could be improved, I hope that they are all:

  • auditable;
  • able to be implemented by one or more well-defined processes;
  • understandable by both those who concerned with the governance level and those involved at the process implementation and operations level.

The value of auditing

I’ve written about auditing before (Confessions of an auditor).  I think it’s really important.  Done well, it should allow you to discover whether:

  1. your processes are covering all of the eventualities of your policies;
  2. whether your policies are actually being implemented correctly.

Auditing may also address whether your policies fully meet your governance model.  Auditing well is a skill, but in order to help your auditor – whether they are good at it or bad at it – having a clearly defined set of policies is a must.  But, as I pointed out at the beginning of this article, policies for policies’ sake are worthless: put them together with governance and processes, however, and they provide technical and business value.

1 – this is sarcasm.

2 – yes, I know.  But let’s not be rude if we can avoid it.  We want to help managers, because the more clue we deliver to them, the easier our lives will be[3].

3 – and you never know: one day, even you might be a manager.

4 – which is probably not a US military base, given the spelling of “authorised”.

5 – example only…

6 – this, in my experience, is the correct answer to many questions.

Who do you trust: your data, or your enemy’s?

Our security logs define our organisational memory.

Imagine, just imagine, that you’re head of an organisation, and you suspect that there’s been some sort of attack on your systems[1].  You don’t know for sure, but a bunch of your cleverest folks are pretty sure that there are sufficient signs to merit an investigation.  So, you agree to allow that investigation, and it’s pretty clear from the outset – and becomes yet more clear as the investigation unfolds – that there was an attack on your organisation.  And as this investigation draws close to its completion, you happen to meet the head of another organisation, which happens to be not only your competitor, but also the party that your investigators are certain was behind the attack.  That person – the leader of your competitor – tells you that they absolutely didn’t perform an attack: no, sirree.  Who do you believe?  Your people, who have been laboring[2] away for months, or your competitor?

What a ridiculous question: of course you’d believe your own people over your competitor, right?

So, having set up such an absurd scenario[4], let’s look at a scenario which is actually much more likely.  Your systems have been acting strangely, and there seems to be something going on.  Based on the available information, you believe that you’ve been attacked, but you’re not sure.  Your experts think it’s pretty likely, so you approve an investigation.  And then one of your investigatory team come to you to tell you some really bad news about the data.  “What’s the problem?” you ask.  “Is there no data?”

“No,” they reply, “it’s worse than that.  We’ve got loads of data, but we don’t know which is real.”

Our logs are our memory

There is a literary trope – one of my favourite examples is Margery Allingham’s The Traitor’s Purse – where a character realises that he or she is somebody other than who they think they are when they start to question their memories.  We are defined by our memories, and the same goes for organisational security.  Our security logs define our organisational memory.  If you cannot prove that the data you are looking at is[5] correct, then you cannot be sure what led to the state you are in now.

Let’s give a quick example.  In my organisation, I am careful to log every time I upgrade a piece of software, but I begin to wonder whether a particular application is behaving as expected.  Maybe I see some traffic to an external IP address which I’ve never seen before, for instance.  Well, the first thing I’m going to do is to check the logs to see whether somebody has updated the software with a malicious version.  Assuming that somebody has installed a malicious version, there are three likely outcomes at this point:

  1. you check the logs, and it’s clear that a non-authorised version was installed.  This isn’t good, because you now know that somebody has unauthorised access to your system, but at least you can do something about it.
  2. at least some of the logs are missing.  This is less good, because you really can’t be sure what’s gone on, but you know have a pretty strong suspicion that somebody with unauthorised access has deleted some logs to cover up their tracks, which means that you have a starting point for remediation.
  3. there’s nothing wrong.  All the logs look fine.  You’re now really concerned, as you can’t be sure of your own data – your organisation’s memories.  You may be looking at correct data, or you may be looking at incorrect data: data which has been written by your enemy.  Attackers can – and do – go into log files and change the data in them to obscure the fact that they have performed particular actions.  It’s actually one of the first steps that a competent attacker will perform.

In the scenario as defined, things probably aren’t too bad: you can check the checksum or hash of the installed software, and check that it’s the version you expect.  But what if the attacker has also changed the version of your checksum- or hash-checker so that, for packages associated with this particular application, they always return what you expect to see?  This is not a theoretical attack, and nor is it the only way approach that attackers have to try to muddy the waters as to what they’ve done. And if it has happened, they you have no way of confirming that you have the correct version of the application.  You can try updating the checksum- or hash-checker, but what if the attacker has meddled with the software installer to ensure that it always installs their version…?

It’s a slippery slope, and bar wiping the entire system and reinstalling[6], there’s little you can do to be certain that you’ve cleared things up properly.  And in some cases, it may be too late: what if the attacker’s main aim was to exfiltrate some of your proprietary data, for example?

Lessons to learn, actions to take

Well, the key lesson is that your logs are important, and they need to be protected.  If you can’t trust your logs, then it can be very, very difficult not only to identify the extent of an attack, but also to remediate it or, in the worst case, even to know that you’ve been attacked at all.

And what can you do?  Well, there are many techniques that you can employ, and the best combination will depend on a number of questions, including your regulatory regime, your security posture, and what attackers you decide to defend against.  I’d start with a fairly simple combination:

  • move your most important logs off-system.  Where possible, host logs on different systems to the ones that are doing the reporting.  If you’re an attacker, it’s more difficult to jump from one system to another than it is to make changes to logs on a system which you’ve already compromised;
  • make your logs write-only.  This sounds crazy – how are you supposed to check logs if they can’t be read?  What this really means is that you separate read and write privileges on your logs so that only those with a need to read them can do so.  Writing is less worrisome – though there are attacks here, including filesystem starvation – because if you can’t see what you need to change, then it’s almost impossible to do so.  If you’re an attacker, you might be able to wipe some logs – see our case 2 above – but obscuring what you’ve actually done is more difficult.

Exactly what steps you take are up to you, but remember: if you can’t trust your logs, you can’t trust your data, and if you can’t trust your data, you don’t know what has happened.  That’s what your enemy wants: confusion.

1 – like that’s ever going to happen.

2- on this, very rare, occasion, I’m going to countenance[2] a US spelling.  I think you can guess why.

3 – contenance?

4 – I know, I know.

5 – are?

6 – you checked the firmware, right?  Hmm – maybe safer just to buy completely new hardware.

 

Confessions of an auditor

Moving to a postive view of security auditing.

So, right up front, I need to admit that I’ve been an auditor.  A security auditor.  Professionally.  It’s time to step up and be proud, not ashamed.  I am, however, dialled into a two-day workshop on compliance today and tomorrow, so this is front and centre of my thinking right at the moment.  Hence this post.

Now, I know that not everybody has an entirely … positive view of auditors.  And particularly security auditors[1].  They are, for many people, a necessary evil[2].  The intention of this post is to try to convince you that auditing[3] is, or can and should be, a Force for Good[tm].

The first thing to address is that most people have auditors in because they’re told that they have to, and not because they want to.  This is often – but not always – associated with regulatory requirements.  If you’re in the telco space, the government space or the financial services space, for instance, there are typically very clear requirements for you to adhere to particular governance frameworks.  In order to be compliant with the regulations, you’re going to need to show that you meet the frameworks, and in order to do that, you’re going to need to be audited.  For pretty much any sensible auditing regime, that’s going to require an external auditor who’s not employed by or otherwise accountable to the organisation being audited.

The other reason that audit may happen is when a C-level person (e.g. the CISO) decides that they don’t have a good enough idea of exactly what the security posture of their organisation – or specific parts of it – is like, so they put in place an auditing regime.  If you’re lucky, they choose an industry-standard regime, and/or one which is actually relevant to your organisation and what it does.  If you’re unlucky, … well, let’s not go there.

I think that both of the reasons above – for compliance and to better understand a security posture – are fairly good ones.  But they’re just the first order reasons, and the second order reasons – or the outcomes – are where it gets interesting.

Sadly, one of key outcomes of auditing seems to be blame.  It’s always nice to have somebody else to blame when things go wrong, and if you can point to an audited system which has been compromised, or a system which has failed audit, then you can start pointing fingers.  I’d like to move away from this.

Some positive suggestions

What I’d like to see would be a change in attitude towards auditing.  I’d like more people and organisations to see security auditing as a net benefit to their organisations, their people, their systems and their processes[4].  This requires some changes to thinking – changes which many organisations have, of course, already made, but which more could make.  These are the second order reasons that we should be considering.

  1. Stop tick-box[5] auditing.  Too many audits – particularly security audits – seem to be solely about ticking boxes.  “Does this product or system have this feature?”  Yes or no.  That may help you pass your audit, but it doesn’t give you a chance to go further, and think about really improving what’s going on.  In order to do this, you’re going to need to find auditors who actually understand the systems they’re looking at, and are trained to some something beyond tick-box auditing.  I was lucky enough to be encouraged to audit in this broader way, alongside a number of tick-boxes, and I know that the people I was auditing always preferred this approach, because they told me that they had to do the other type, too – and hated it.
  2. Employ internal auditors.  You may not be able to get approval for actual audit sign-off if you use internal auditors, so internal auditors may have to operate alongside – or before – your external auditors, but if you find and train people who can do this job internally, then you get to have people with deep knowledge (or deeper knowledge, at least, than the external auditors) of your systems, people and processes looking at what they all do, and how they can be improved.
  3. Look to be proactive, not just reactive.  Don’t just pick or develop products, applications and systems to meet audit, and don’t wait until the time of the audit to see whether they’re going to pass.  Auditing should be about measuring and improving your security posture, so think about posture, and how you can improve it instead.
  4. Use auditing for risk-based management.  Last, but not least – far from least – think about auditing as part of your risk-based management planning.  An audit shouldn’t be something you do, pass[6] and then put away in a drawer.  You should be pushing the results back into your governance and security policy model, monitoring, validation and enforcement mechanisms.  Auditing should be about building, rather than destroying – however often it feels like it.

 

1 – you may hear phrases like “a special circle of Hell is reserved for…”.

2 – in fact, many other people might say that they’re an unnecessary evil.

3 – if not auditors.

4 – I’ve been on holiday for a few days: I’ve maybe got a little over-optimistic while I’ve been away.

5 – British usage alert: for US readers, you’ll probably call this a “check-box”.

6 – You always pass every security audit first time, right?