Somewhere Over The Rainbow – A Story About A Global Ubiquitous Record of All Things Incident

One of my posts from earlier in 2012 discussed the idea that CEOs are to blame for all of our problems in security. The idea that we “must have reliable actuarial data on incidents to stay relevant” is another of the information security holy sacred cows that rears its head every so often, and this post explains covers three angles on the incidents database idea. First I look at the impracticalities of gathering incidents data. Second, even if we have accurate data, exactly how useful is the data to us in the formulation of risk management decisions, and third, even if the data is accurate and useful, did we even need it in the first place?

Shostack and Stewart’s New School book was from the mid-2000s and a chapter is devoted to the absolute necessity of a global, ubiquitous incidents database. Such a thing is proclaimed by many as carrying do or die importance, as if we need it to prove the existence of a threat, and moreover to prove our right to exist as security professionals. Do we really need a global database to prove to the C-levels that spending on security is necessary?

There are of course some real blockers with regard the gathering of incidents data, not least the “what the heck just happened” factor, where post-incident, logging is turned on (it was off until the incident occurred) and $300k invested in a SIEM solution – one that really doesn’t help the business to respond effectively to incidents, it just gives operations a nice vehicle with which they can use to diagnose non-security related problems, and of course the vendor/box pusher consultants knew what they were doing when they configured the thing.

Anyway it really isn’t terribly constructive to talk reality with regard this subject. We need to talk about a theoretical world, somewhere over the rainbow – one where logging is enabled, internal detection controls are well configured, and internal IT ops and sec know how to respond to incidents and they understand log messages. Okay, most businesses don’t even know they were hacked until a botnet command and control box is owned by some supposed good guys somewhere, but all talk of security is null and void if we acknowledge reality here. So let’s not talk reality.

So incidents data simply won’t be available in many cases – that base is now covered. But what are we trying to achieve here? The proposal is to use past incidents data to help us prove the existence of a threat in formulating decisions on risk. We receive a penetration test report that tells us that vulnerability X was compromised 4 years ago in Timbuctoo. The other vulnerabilities mentioned in the report – according to our accurate database there is no mention of them ever having been compromised with resulting financial damage. So we fix vulnerability X and ignore the rest – a wise strategy, especially given that our incidents database hosts accurate information with check-sums and integrity built-in (well – I did say let’s not talk reality here).

But wait a minute – vulnerability X was exploited 4 years ago in a company Y in an industry sector Z. What if company Y’s network was wide open? Where is this leading? All networks are different. All businesses face different challenges. Even those in the same industry sector as each other are completely different. How ludicrous this is getting? Business X can even have the exact same network architecture as another business Y in the same industry sector, and yet the exploitation of the same vulnerability X in business X can lead to $100K damages for business X, but $100 damages in business Y. So are we really going to use these records of financial damages to formulate our risk acceptance, transferal, or mitigation decision? One would hope not.

As if this all isn’t bad enough: even if we ignore the hard reality of the limitations covered here, how long would it take before we have gathered enough information to call the database useful? 10 years? 20 years? One million incidents or…? Products are past their shelf life in less than a decade generally. I did come across an IBM AIX 4.1 (we’re talking mid-to-late 90s here) box at a customer site not so long ago, but thankfully that was an isolated incident.

After all the deliberation, it emerges that security is too complex – it cannot be reduced down to a simple picture a la “vulnerability X was exploited resulting in damages Y in company Z, and therefore we in Botnetz R Us need to address vulnerability X”.

All this is not to say that there is no benefit in knowing what’s going off out there in the wild. We can pick up on on-going bigger picture attack trends to enable us to prepare for what might be down the road for us. But do we really need details of past incidents to convince businesses to part with cash in risk mitigation, or moreover validate our existence?

What we’re really concerned with here is trust. The proponents of a big data repository of incident big data would have it that we need such a thing because the powers that be don’t trust us. When we propose a mitigation of a particular risk, they don’t trust our advice. Unfortunately though, we might get one success story where we consult the oracle of all incidents and we do magically find an incident related to the problem we are trying to fix, and we use this “evidence” to convince the bosses. What about the next problem though? We can’t use the same card trick next time to address the next risk issue if no such problem was ever encountered (and reported) before by another company somewhere else in the world. By looking into the history of all incidents we’re setting a dangerous precedent, and rather than enabling trust, we’re making the situation even worse.

We don’t need an incidents history record. What we need is for our customers to trust us. Our customers are C-levels, other business units, home users, in-house reps, and so on. How do we get them to trust us? What we need is a single accreditation path for security professionals, one that ties Analysts to past experience as an IT admin or developer, and one that ties Security Managers with past Analyst experience. With this, security managers can confidently deliver risk-related advisories to their superiors, safe in the knowledge that their message is backed up by Analysts with solid tech experience, and in whose advice they are comfortable in placing their trust.

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Blame The CEO?

I would like to start by issuing a warning about the content in this article. I will be taking cynicism to the next level, so the baby-eyed, and “positive” among us should avert their gaze after this first paragraph. For those in tune with their higher consciousness, I will summarise: Can we blame the C-levels for our problems? Answer: no. Ok, pass on through now. More positive vibes may be found in the department of delusion down the hall.

The word “salt” was for the first time ever inserted into the hall of fame of Information Security buzzwords after the Linkedin hack infamy, and then Yahoo came along and spoiled the ridicule-fest by showing to the world that they could do even better than Linkedin by not actually using any password hashing at all.

There is a tendency among the masses to latch onto little islands of intellectual property in the security world. Just as we see with “cloud”, the “salt” element of the Linkedin affair was given plenty of focus, because as a result of the incident, many security professionals had learned something new – a rare occurrence in the usual agenda of tick-in-box-marking that most analysts are mandated to follow.

With Linkedin, little coverage was given to the tedious old nebulous “compromise” element, or “how were the passwords compromised?”. No – the “salt” part was much more exciting to hose into blogs and twitter – but with hundreds of analysts talking about the value of “salting”, the value of this pearl of wisdom was falling exponentially with time – there was a limited amount of time in which to become famous. If you were tardy in showing to the world that you understood what “salting” means, your tweet wouldn’t be favourite’d or re-tweeted, and the analyst would have to step back off the stage and go back to their usual humdrum existence of entering ticks in boxes, telling devs to use two-factor authentication as a matter of “best practices”, “run a vulnerability scanner against it”, and such ticks related matters.

Infosec was down and flailing around helplessly, then came the Linkedin case. The inevitable fall-out from the “salting” incident (I don’t call it the Linkedin incident any more) was a kick of sand in the face of the already writhing information security industry. Although I don’t know of any specific cases, based on twelve happy years of marriage with infosec, i’m sure they’re as abundant as the stars and occurring as I write this. I am sure that nine times out of ten, whenever devs need to store a password, they are told by CISSP-toting self-righteous analysts (and blindly backed up by their managers) that it is “best practice” and “mandatory” to use salting with passwords – regardless of all the other factors that go into making up the full picture of risk, the operational costs, and other needless over-heads. There will be times when salting is a good idea. Other times not. There cannot be a zero-value proposition here – but blanket, parrot-fashion advisories are exactly that.

The subject matter of the previous four paragraphs serves as a recent illustrator of our plight in security. My book covers a much larger piece of the circus-o-sphere and its certainly too much to even to try to summarise here, but we are epic-failing on a daily basis. One of the subjects I cover in Security De-engineering is the role of C-Level executives in security, and I ask the question “can we blame the C-levels” for the broken state of infosec?

Let’s take a trip down memory lane. The heady days of the late 90s were owned by technical wizards, sometimes known as Hackers. They had green hair and piercings. If a CEO ran some variant of a Windows OS on her laptop, she was greeted with a stream of expletives. Ok, “best practices” was nowhere to be seen in the response, and it is a much more offensive swear-phrase than any swear word I can think of, but the point is that the Hacker’s reposte could be better.

Hackers have little or no business acumen. They have the tech talent that the complexities of information security afford, but back when they worked in infosec in the late 90s, they were poorly managed. Artists need an agent to represent them, and there were no agents.

Hackers could theoretically be locked in a room with a cat-flap for food and drink, no email, and no phone. The only person they should be allowed to communicate with is their immediate security line manager. They could be used as a vault of intellectual capital, or a swiss army knife in the organisation. Problem was – the right kind of management was always lacking. Organisations need an interface between themselves and the Hackers. No such interface ever existed unfortunately.

The upper levels of management gave up working with Hackers for various reasons, not just for scaring the living daylights out of their normal earthling colleagues. Then came the early noughties. Hackers were replaced by respectable analysts with suits and ties, who sounded nice, used the words “governance” and “non-repudiation” a lot, and didn’t swear at their managers regardless of ineptitude levels. The problem with the latter CASE (Checklist and Standards Evangelist) were illustrated with the “salting” debacle and Linkedin.

There is a link between information and information security (did you notice the play on words there – information was used in…”information”… and also in… “information security” – thereby implicating that there might just be a connection). The CASE successor to the realm actually managed to convince themselves (but few others in the business world) that security actually has nothing to do with information technology. It is apparently all about “management” and “processes”. So – every analyst is now a “manager”?! So who in the organisation is going to actually talk to ops and devs and solve the risk versus cost of safeguard puzzles? There are no foot soldiers, only a security department composed entirely of managers.

Another side of our woes is the security products space. Products have been lobbied by fierce marketing engines and given ten-out-of-ten ratings by objective information security publications. The products supposedly can automate areas of information risk management, and tell us things we didn’t already know about our networks. The problem is when you automate processes, you’re looking for accurate results. Right? Well, in certain areas such as vulnerability assessment, we don’t even get close to accurate results – and vulnerability assessment is one area where accuracy is sorely needed – especially if we are using automation to assess vulnerability in critical situations.

Some product classes do actually make some sense to deploy in some business cases, but the number of cases where something like SIEM (for example) actually make sense as as an investment is a small number of the whole.

Security line managers feel the pressure of compliance as the main part of their function. In-house advice is pretty much of the out-house variety in most cases, and service providers aren’t always so objective when it comes to technology acquisition. Products are purchased as a show of diligence for clueless auditors and a short cut to a tick-in-a-box.

So the current security landscape is one of a lack of appropriate skills, especially at security line-management level, which in turn leads to market support for whatever bone-headed product idea can be dreamed up next. The problems come in two boxes then – skills and products.

Is it the case that security analysts and line managers are all of the belief that everything is fine in their corner? The slew of incidents, outgoing connections to strange addresses in eastern Europe, and the loss of ownership of workstation subnets – it’s not through any fault of information security professionals? I have heard some use the excuse “we can never keep out bad guys all the time” – which actually is true, but there is little real confidence in the delivery of this message. Even with the most confidence – projecting among us, there is an inward sense of disharmony with things. We all know, just from intuition, that security is about IT (not just business) and that the value we offer to businesses is extremely limited in most cases.

CEOs and other silver-heads read non-IT publications, and often-times incidents will be reported, even in publications such as the Financial Times. Many of them are genuinely concerned about their information assets, and they will ask for updates from someone like a CISO. It is unlikely the case, as some suggest, they don’t care about information security and it is also unlikely, as is often claimed, that security budgets are rejected minus any consideration.

CEOs will make decisions on security spending based on available information. Have they ever been in a position where they can trust us with our line reporting? Back in the 90s they were sworn at with business-averse rhetoric. Later they were bombarded with IT-averse rhetoric, green pie charts from expensive vulnerability management suites, delivered with a perceptible lack of confidence in analyst skills and available tools.

So can we blame CEOs? Of course not, and our prerogative now should be re-engineering of skills, with a better system of “graduation” through the “ranks” in security, and an associated single body of accreditation (Chapter 11 of Security De-engineering covers this in more detail). With better skills, the products market would also follow suit and change radically. All of this would enable CISOs to report on security postures with confidence, which in turn enables trust at the next level up the ladder.

The idea that CEOs are responsible for all our problems is one of the sacred holy cows of the security industry (along with some others that I will be covering). Ladies and gentlemen: security analysts, managers, self-proclaimed “Evangelists”, “Subject Matter Experts”, and other ego-packing gurus of our time are responsible for the problems.

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A Tribute To Our Oldest And Dearest Of Friends – The Firewall (Part 2)

In the first part of my coverage on firewalls I mentioned about the usefulness of firewalls, and apart from being one of the few commercial offerings to actually deliver in security, the firewall really does do a great deal for our information security posture when its configured well.

Some in the field have advocated that the firewall has seen its day and its time for the knackers yard, but these opinions are borne from a considerable distance from the coal face in this business. Firewalls, when seen as something as in the movies, as in “breaking through”, “punching through” the firewall, can be seen as useless when bad folk have compromised networks seemingly effortlessly. One doesn’t “break through” a firewall. Your profile is assessed. If you fit a certain profile you are allowed through. If not, you absolutely shall not pass.

There have been counters to these arguments in support of firewalls, but the extent of the efficacy of well-configured firewalls has only been covered with some distance from the nuts and bolts, and so is not fully appreciated. What about segmentation for example? Are there any other security controls and products that can undisputedly be linked with cost savings? Segmentation allows us to devote more resources to more critical subnets, rather than blanket measures across a whole network. As a contractor with a logistics multinational in Prague, I was questioned a few times as to why I was testing all internal Linux resources, on a standard issue UK contract rate. The answer? Because they had a flat, wide open internal network with only hot swap redundant firewalls on the perimeter. Regional offices connecting into the data centre had frequent malware problems with routable access to critical infrastructure.

Back in the late 90s, early noughties, some service providers offered a firewall assessment service but the engagements lacked focus and direction, and then this service disappeared altogether…partly because of the lack of thought that went into preparation and also because many in the market really did believe they had nailed firewall configuration. These engagements were delivered in a way that was something like “why do you leave these ports open?”, “because this application X needs those ports open”…and that would be the end of that, because the service providers didn’t know application X, or where its IT assets were located, or the business importance of application X. After thirty minutes into the engagement there were already “why are we here?” faces in the room.

As a roaming consultant, I would always ask to see firewall configurations as part of a wider engagement – usually an architecture workshop whiteboard session, or larger scale risk assessment. Under this guise, there is license to use firewall rulebases to tell us a great deal about the organisation, rather than querying each micro-issue.

Firewall rulebases reveal a large part of the true “face” of an organization. Political divisions are revealed, along with the old classic: opening social networks, betting sites (and such-like) only for senior management subnets, and often times some interesting ports are opened only for manager’s secretaries.

Nine times out of ten, when you ask to see firewall rules, faces will change in the room from “this is a nice time wasting meeting, but maybe I’ll learn something about security” to mild-to-severe discomfort. Discomfort – because there is no hiding place any more. Network and IT ops will often be aware that there are some shortcomings, but if we don’t see their firewall rules, they can hide and deflect the conversation in subtle ways. Firewall rulebases reveal all manner of architectural and application – related issues.

To illustrate some firewall configuration and data flow/architectural issues, here are some examples of common issues:

– Internal private resources 1-to-1 NAT’d to pubic IP addresses: an internal device with a private RFC 1918 address (something like 10. or 192.168. …) has been allocated a public IP address that is routable from the public Internet and clearly “visible” on the perimeter. Why is this a problem? If this device is compromised, the attacker has compromised an internal device and therefore has access to the internal network. What they “see” (can port scan) from there depends on internal network segmentation but if they upload and run their own tools and warez on the compromised device, it won’t take long to learn a great deal about the internal network make-up in these cases. This NAT’ing problem would be a severe problem for most businesses.

– A listening service was phased out, but the firewall still considers the port to be open: this is a problem, the severity of which is usually quite high but just like everything else in security, it depends on a lot of factors. Usually, even in default configurations, firewalls “silently drop” packets when they are denied. So there is no answer to a TCP SYN request from a port scanner trying to fire-up some small talk of a long winter evening. However, when there is no TCP service listening on a higher port (for example) but the firewall also doesn’t block access to this port – there will be a quick response to the effect “I don’t want to talk, I don’t know how to answer you, or maybe you’re just too boring” – this is bad but at least there’s a response. Let’s say port 10000 TCP was left unfiltered. A port scanner like nmap will report other ports as “filtered” but 10000 as “closed”. “Closed” sounds bad but the attacker’s eye light up when seeing this…because they have a port with which to bind their shell – a port that will be accessible remotely. If all ports other than listening services are filtered, this presents a problem for the attacker, it slows them down, and this is what we’re trying to achieve ultimately.

– Dual-homed issues: Sometimes you will see internal firewalls with rules for source addresses that look out of place. For example most of the rules are defined with 10.30.x.x and then in amidst them you see a 172.16.x.x. Oh oh. Turns out this is a source address for a dual-homed host. One NIC has an address for a subnet on one side of a firewall, plus one other NIC on the other side of the firewall. So effectively the dual-homed device is bypassing firewall controls. If this device is compromised, the firewall is rendered ineffective. Nine times out of ten, this dual homing is only setup as a short cut for admins to make their lives easier. I did see this once for a DMZ, where the internal network NIC address was the same subnet as a critical Oracle database.

– VPN gateways in inappropriate places: VPN services should usually be listening on a perimeter firewall. This enables firewalls to control what a VPN user can “see” and cannot see once they are authenticated. Generally, the resources made available to remote users should be in a VPN DMZ – at least give it some consideration. It is surprising (or perhaps not) how often you will see VPN services on internal network devices. So on firewalls such as the inner firewall of a DMZ, you will see classic VPN TCP services permitted to pass inbound! So the VPN client authenticates and then has direct access to the internal network – a nice encrypted tunnel for syphoning off sensitive data.

Outbound Rules

Outbound filtering is often ignored, usually because the business is unaware of the nature of attacks and technical risks. Inbound filtering is usually quite decent, but its still the case as of 2012 that many businesses do not filter any outbound traffic – as in none whatsoever. There are several major concerns when it comes to egress considerations:

– Good netizen: if there is no outbound filtering, your site can be broadcasting all kinds of traffic to all networks everywhere. Sometimes there is nothing malicious in this…its just seen as incompetence by others. But then of course there is the possibility of internal staff hacking other sites, or your site can be used as a base from which to launch other attacks – with a source IP address registered under the ownership of the source of the attack – and this is no small matter.

– Your own firewall can be DOS’d: Border firewalls NAT outgoing traffic, with address translation from private to public space. With some malware outbreaks that involve a lot of traffic generation, the NAT pool can fill quickly and the firewall NAT’ing can fail to service legitimate requests. This wouldn’t happen if these packets are just dropped.

– It will be an essential function of most malware and manual attacks to be able to dial home once “inside” the target – for botnets for example, this is essential. Plus, some publicly available exploits initiate outbound connections rather than fire up listening shells.

Generally, as with ingress, take the standard approach: start with deny-all, then figure out which internal DNS and SMTP servers need to talk to which external devices, and take the same approach with other services. Needless to say, this has to be backed by corporate security standards, and made into a living process.

Some specifics on egress:

– Netbios broadcasts reveal a great deal about internal resources – block them. In fact for any type of broadcast – what possible reason can there be for allowing them outside your network? There are other legacy protocols which broadcast nice information for interested parties – Cisco Discovery Protocol for example.

– Related to the previous point: be as specific as possible with subnet masks. Make these as “micro” as possible.

– There is a general principle around proxies for web access and other services. The proxy is the only device that needs access to the Internet, others can be blocked.

– DNS: Usually there will be an internal DNS server in private space which forwards queries to a public Internet DNS service. Make sure the DNS server is the only device “allowed out”. Direct connections from other devices to public Internet services should be blocked.

– SMTP: Access to mail services is important for many malware variants, or there is mail client functionality in the malware. Internal mail servers should be the only devices permitted to connect to external SMTP services.

As a final note, for those wishing to find more detail, the book I mentioned in part 1 of this diatribe, “Building Internet Firewalls” illustrates some different ways to set up services such as FTP and mail, and explains very well the principles of segregated subnets and DMZs.

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A Tribute To Our Oldest And Dearest Of Friends – The Firewall (Part 1)

In my previous article I covered OS and database security in terms of the neglect shown to this area by the information security industry. In the same vein I now take a look at another blast from the past – firewalls. The buzz topics these days are cloud, big data, APT, “cyber”* and BYOD. Firewall was a buzz topic a very long time ago, but the fact that we moved on from that buzz topic, doesn’t mean we nailed it. And guess what? The newer buzz topics all depend heavily on the older ones. There is no cloud security without properly configured firewalls (and moving assets off-campus means even more thought has to be put into this area), and there shouldn’t be any BYOD if there is no firewall(s) between workstation subnets and critical infrastructure. Good OS/DB security, plus thoughtful firewall configs sets the stage on which the new short-sighted strategies are played out and retrenched.

We have a lot of bleeding edge software and hardware products in security backed by fierce marketing engines which set unrealistic expectations, advertised with 5 gold star ratings in infosec publications, coincidentally next to a full page ad for the vendor. Out of all these products, the oldest carries the highest bang for our bucks – the firewall. In fact the firewall is one of the few that actually gives us what we expect to get – network access control, and by and large, as a technology it’s mature and it works. At least when we buy a firewall looking for packet filtering, we get packet filtering, unlike another example where we buy a product which allegedly manages vulnerability, but doesn’t even detect vulnerability, let alone “manage” it.

Passwords, crypto, filesystem permissions – these are old concepts. The firewall arrived on the scene some considerable number of years after the aforementioned, but before some of the more recent marketing ideas such as IdM, SIEM, UTM etc. The firewall, along with anti-virus, formed the basis of the earliest corporate information security strategies.

Given the nature of TCP/IP, the next step on from this creation was quite an intuitive one to take. Network access control – not a bad idea! But the fact that firewalls have been around corporate networks for two decades doesn’t mean we have perfected our approach to configuration and deployment of firewalls – far from it.

What this article is not..

“I’m a firewall, I decide which packets are dropped or passed based on source and destination addresses and services”.

Let’s be clear, this article is not about which firewall is the best. New firewall, new muesli. How does one muesli differ from another? By the definition of muesli, not much, or it’s not muesli any more.

Some firewalls have exotic features – even going back 10 years, Checkpoint Firewall-1 had application layer trackers such as FTP passive mode trackers, earlier versions of which crashed the firewall if enabled – thereby introducing DoS as an innovative add-on. In most cases firewalls need to be able to track conversations and deny/pass packets based on unqualified TCP flags (for example) – but these days they all do this. Firewalls are not so CPU intensive but they can be memory-intensive if conversations are being monitored and we’re being DoS’d – but being a firewall doesn’t make a node uniquely vulnerable to SYN-Flood and so on. The list of considerations in firewall design goes on and on but by 2012 we have covered off most of the more important, and you will find the must-haves and the most useful features in any modern commercial firewall…although I wouldn’t be sure that this covers some of the UTM all-in-one matchbox size offerings.

Matters such as throughput and bandwidth are matters for network ops in reality. Our concern in security should be more about configuration and placement.

On the matter of which firewall to use, we can go back to the basic tenet of a firewall as in the first paragraph of this subsection – sometimes it is perfectly fine to cobble together an old PC, install Linux on it, and use iptables – but probably not for a perimeter choke point firewall that has to handle some considerable throughput. Likewise, do you want the latest bright flashing lights, bridge of the Starship Enterprise enterprise box for the firewall which separates a 10-node development subnet from the commercial business production subnets? Again, probably not – let’s just keep an open mind. Sometimes cheap does what we need. I didn’t mention the term “open source” here because it does tend to evoke quite emotional responses – ok well i did mention it actually, sorry, just couldn’t help myself there. There are the usual issues with open source such as lack of support, but apart from bandwidth, open source is absolutely fine in many cases.

Are firewalls still important?

All attack efforts will be successful given sufficient resources. What we need to do is slow down these efforts such that the resources required outweighs the potential gains from owning the network. Effective firewall configuration helps a great deal in this respect. I still meet analysts who underestimate the effect of a firewall on the security posture.

Taking the classic segregated subnet as in a DMZ type configuration, by now most of us are aware at least that a DMZ is in most cases advisable, and most analysts can draw a DMZ network diagram on a white board. But why DMZ? Chiefly we do this to prevent direct connections from untrusted networks to our most valuable information assets. When an outsider port scans us, we want them to “see” only the services we intend the outside world to see, which usually will be the regular candidates: HTTPs, VPN, etc. So the external firewall blocks access to all services apart from those required, and more importantly, it only allows access to very specific DMZ hosts, certainly no internal addresses should be directly accessible.

Taking the classic example of a DMZ web server application that connects to an internal database. Using firewalls and sensible OS and database configuration, we can create a situation where we can add some considerable time on an attack effort aimed at compromising the database. Having compromised the DMZ webserver, port scanning should then reveal only one or two services on the internal database server, and no other IP addresses need to be visible (usually). The internal firewall limits access from the source address of the DMZ webserver, to only the listening database service and the IP address of the destination database server. This is a considerably more challenging situation for attackers, as compared with a scenario where the internal private IP space is fully accessible…perhaps one where DMZ servers are not at all segregated and their “real” IP addresses are private RFC 1918 addresses, NAT’d to public Internet addresses to make them routable for clients.

Firewalls are not a panacea, especially with so many zero days in circulation, but in an era where even automated attacks can lead to our most financially critical assets disappearing via the upstream link, they can, and regularly do, make all the difference.

We All “Get” Firewalls…right?

There is no judgment being passed here, but it often is the case that security departments don’t have much to offer when it comes to firewall configuration and placement. Network and IT operations teams will try perhaps a couple of times to get some direction with firewalls, but usually what comes back is a check list of “best practices” and “deny all services that are not needed”, some will even take the extraordinary measure of reminding their colleagues about the default-deny, “catch all” rule. But very few security departments will get more involved than this.

IT and network ops teams, by the year 2012 AD, are quite averse in the wily ways of the firewall, and without any further guidance they will do a reasonable job of firewall configuration – but 9 times out of 10 there will be shortcomings. Ops peeps are rarely schooled on the art of technical risks. Its not part of their training. If they do understand the tech risk aspects of network access control, it will have been self-taught. Even if they have attended a course by a vendor, the course will cover the usage aspects, as in navigating GUIs and so on, and little of any significance to keeping bad guys out.

Ops teams generally configure fairly robust ingress filtering, but rarely is there any attention given to egress (more on that in part 2 of this offering), and the importance of other aspects such as whether services are UDP or TCP (with the result that one or other other is left open).

Generally, up to now, there are still some gaps and areas where businesses fall short in their configuration efforts, whereas I am convinced that in many cases attention moved away from firewalls many years ago – as if it’s an area that we have aced and so we can move on to other things.

So where next?

I would like to bring this diatribe to a close for now, until part 2. In the interim I would also like to point budding, enthusiastic analysts, SMEs, Senior *, and Evangelists in the direction of some rather nice reads. Try out TCP/IP Illustrated, at least Volume 1. Then O’ Reilly’s “Building Internet Firewalls”. The latter covers the in and outs of network architecture and how to firewall specific commonly used application layer protocols. This is a good starting point. Also, try some hands-on demo work (sorry – this involves using command shells) with IPtables – you’ll love it (I swear by this), and pay some attention to packet logging.

In Part 2 I will go over some of my experiences as a consultant with a roaming disposition, related to firewall configuration analysis, and I will cover some guiders related to classic misconfigurations – some of which may not be so obvious to the reader.

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