An operating system has reached End of Support (EoS) so no more security patches are coming for the OS ever. An embedded device running this OS needs to be updated to a newer version. However, the engineers who designed the original product feel that the machine is not hackable and therefore does not need to be patched. The device has WiFi, Ethernet, USB ports and an OS that has reached EoS.

The questions I am asked daily:

  1. We have application white-listing so why do we need to patch vulnerabilities?
  2. We have a firewall so why do we need to patch vulnerabilities?

And the comments I get:

Our plan is to harden the system even more. If we do this then we should not have to update the OS and continue patching it. No one will be able to reach the vulnerabilities. Also we will fix the vulnerabilities in outward-facing parts of the OS (even though there is no ability for them to patch the vulnerabilities themselves) and then we can leave the non-outside facing vulnerabilities unpatched.

I have explained in detail about Nessus credentialed scans. I am not sure how to get my point across to these engineers. Any thoughts on how I can explain this?

UPDATE: The system is being patched. Thanks for everyones responses and help.

  • 194
    " the engineers who designed the original product feel that the machine is not hackable". I do not know the engineer nor the machine, but I do know that he/she is wrong.
    – dr_
    Commented Dec 22, 2017 at 10:42
  • 172
    "System is unhackable" This is where you laugh out loud. Anyone who thinks a system is unhackable does not understand how amazingly clever and resourceful attackers are. All systems are hackable given enough time and resources. The goal of security is to make the investment required a successful attack higher than the benefit of attacking.
    – jpmc26
    Commented Dec 22, 2017 at 11:22
  • 13
    Asking the customers is a great idea. Just consider that if reputation is actually your main concern and your customers are even just remotely familiar with IT subjects, when you ask your customers I would not mention to them that your engineers feel that the thing is unhackable; such claim has rightfully the potential of hurting reputation greattly. Commented Dec 22, 2017 at 14:06
  • 97
    Coming soon to a DailyWTF article near you... "But the system is unhackable! How could this have happened?! It must be KEN'S fault! That incompetent jerk broke the firewall whitelist with his patching!"
    – corsiKa
    Commented Dec 22, 2017 at 15:57
  • 12
    Despite how anyone feels about a system's security, it seems to me that you would want to try to patch every known vulnerability or at least have a very good reason why you couldn't. Because if you do end up getting hacked, "we didn't bother to apply any patches because we thought it was unhackable" is not a very good defense in any following investigation.
    – Herohtar
    Commented Dec 22, 2017 at 16:36

15 Answers 15


The trouble with the situation (as you are reporting it) is that there are a lot of assumptions being made with a lot of opinions. You have your opinions and you want them to share your opinions, but they have their own opinions.

If you want to get everyone to agree to something, you need to find common ground. You need to challenge and confirm each assumption and find hard data to support your opinion or theirs. Once you have common ground, then you can all move forward together.

  1. You have whitelisting: great, what does that mean? Are there ways around it? Can a whitelisted application be corrupted?
  2. What does the firewall do? How is it configured? Firewalls mean blocked ports, but they also mean allowed ports. Can those allowed ports be abused?
  3. No one has access? Who has access to the device? Are you trusting an insider or the ignorance of a user to keep it secure?
  4. What happens if someone gets local access to the device? How likely is that?

As an information security professional, your job is not to beat people over the head with "best practices" but to perform risk analyses and design a way forward that limits risk under the risk threshold in a cost-effective way. You have to justify not employing best practices, but if the justification is valid, then it's valid.

  • 13
    I apreciate this. I think I am guilty beating people over the head with "best practices". I was able to find evidence that the white listing can be hacked. There is access to the machine but not the OS desktop. Thanks Again.
    – Ken
    Commented Dec 22, 2017 at 10:32
  • 10
    @Ken what you should read between the lines of the last paragraph is that best practices aren't always best.
    – Blrfl
    Commented Dec 22, 2017 at 13:16
  • 4
    Best practices are based on current knowledge. Nobody is omniscient, so current best practices do not stay that way forever. Once current best practices become obsolete, it is due to some fundamental flaw newly discovered.
    – Nelson
    Commented Dec 22, 2017 at 16:34
  • 13
    Best practice is not to rely on an enumerated list of known-today best practices, but to make your system foolproof by not assuming it's unhackable, and designing it accordingly. Commented Dec 22, 2017 at 17:41
  • 11
    @Ken "There is access to the machine but not the OS desktop" - I open your machine, connect a disk with my own OS on it, boot it, and then make whatever changes I want to anything and everything on your system. Or I just open it, take your disk out, and sell it to the highest bidder.
    – aroth
    Commented Dec 23, 2017 at 13:02

If someone tells me that their machine is not hackable and I ought to believe them, I immediately conclude that

  • The machine is kept guarded under Fort Knox/High security prison conditions, with 24/7 guards and security cameras,

and also one of the following:

  • The machine has no exchange of information of any kind (no usb, ethernet, firewire, serial, parallel, etc. of any kind)

  • The machine is permanently turned off.

  • 117
    24/7 guards? Well there you've just got a perfect attack vector! Never underestimate the power of the insider threat.
    – forest
    Commented Dec 22, 2017 at 13:00
  • 42
    The only unhackable system is inside a safe that's been welded shut and pushed off a boat into the Marianas Trench. Then the boat crew was all shot to keep its location secret. Commented Dec 22, 2017 at 14:06
  • 18
    Also, I always get irked at hearing things like "the most secure computer is an unplugged computer", because that completely violates the Availability CIA triad principal. An unplugged computer is the ultimately insecure computer, complete denial of service.
    – forest
    Commented Dec 22, 2017 at 14:14
  • 16
    During our ongoing GSS audit our security people keep hitting us over the head with "gates, guns, and guards are not sufficient" to protect air-gapped media. btw, we're located inside a US army base.
    – doneal24
    Commented Dec 22, 2017 at 16:12
  • 59
    @Adonalsium is pulling the punches. We all know the only unhackable system is one that's crossed the event horizon. Commented Dec 22, 2017 at 18:26

Because you want a multi-layered security strategy with defence in depth. You have a firewall, but what if there's a security vulnerability in your firewall? What if some application exploit gives user-level OS access, and then an unpatched OS vulnerability allows that to be escalated to root access? For proper security you need to patch all known vulnerabilities, not just the ones that you believe can be exploited on your system, because a combination of an unknown vulnerability and a known vulnerability that you believe can't be exploited may allow compromise where either on its own would not, and you can't patch against the unknown vulnerabilities.

  • I was looking for the phrase "defense in depth." That's the simplest answer to these people and usually the best one.
    – Wildcard
    Commented Dec 29, 2017 at 4:06

The reason is simple, security is being applied in layers. For example, to connect to an important database, one needs first to get in the network of the database (pass firewall), add own IP address to the list of the clients allowed to connect, and then initiate the connection with username and password. Any of the layers makes the other two redundant. The problem is "what if". Let's think of the default scott/tiger login of old Oracle or an employee inadvertently forwards a port to the public internet. The firewall may be blocking only TCP, while the server also listens on UDP, or IPv6 is mis-configured, and security only applies for IP4. This is why good security comes in layers, attempts are being monitored and security experts learn from the attempted (hopefully failed) attacks, or they inspect activity on honeypots. Also, zero day exploits (ones that apply even to the latest patch) are less likely to succeed in a layered environment, since the attacker will need an exploit for each layer.

No device is not hackable, just it hasn't been hacked before. Either there is little interests on your device and/or the payoff is very low. Zero day exploits may still exist.

Also, some Android devices simply cannot be upgraded beyond a specific version. Knowing that an adversary has such a device is an open invitation for hacking, since the device name/brand carries the exact recipe of how to hack it.

Maintaining a device without active support is dangerous also from the functional perspective.

Security is not necessary designed to protect from outsiders (firewall) but also from insiders. I don't know the context your device is running, but given what you write, it may be vulnerable to somebody already inside of the firewall.


There are no unhackable systems. For those mentioning airgapping, there are plenty of examples of actual hacks or potential hacks on airgapped systems. Stuxnet is probably the most famous (and most extreme) example. Some others include van Eck phreaking, acoustic analysis, or other side channel attacks.

There are ways to mitigate vulnerabilities that don't involve patching. For instance, if the system is vulnerable to KRACK is it possible to simply disable WiFi? If WiFi is permanently disabled there should be no need to apply any update involving WiFi. Likewise, if there are specific applications on the system that pose a vulnerability (like Java, .NET, Flash, Browsers, etc.) you could simply uninstall those applications. There's no need to update Java if it's not even installed.

With OS upgrades this is admittedly more difficult. You need to be aware of the potential vulnerabilities, then you need to mitigate them. The benefit of using a supported OS is that someone else is (presumably) already doing the first part and half of the second part for you.

A fully updated/upgraded system is not a secure or unhackable system. But it does tend to minimize the risk of KNOWN vulnerabilities. To echo Schroeder, risk analysis is more important than either 'hardening/locking down' or blindly 'upgrading' and hoping that either will make you more secure.

  • 5
    Stuxnet was a result of a violation of the airgap policy, and van eck phreaking and other such attacks violate confidentiality, but not integrity. It would be a far cry to call them "hacking". As for there being "no unhackable systems", EAL7+ stuff comes pretty close!
    – forest
    Commented Dec 22, 2017 at 22:02
  • 3
    That's a nice distinction between confidentiality and integrity. OP didn't mention the goal of the security for the system and my own experience is more heavily focused on risk associated with confidentiality.
    – Meridian
    Commented Dec 22, 2017 at 22:25
  • wired.com/2017/02/malware-sends-stolen-data-drone-just- pcs-blinking-led/ - again, could argue this is a violate of the airgap policy - but still, bit of fun I thought I'd share.
    – user81147
    Commented Jan 24, 2018 at 9:54

No system is truly "unhackable." However once we have decided that a system is "unhackable" enough then we do not have to maintain a channel for security patches.

For a concrete example, our "unhackable" system controls a security camera. The camera's job is to look at a fixed location. Every setting is either constant or the system is smart enough to adjust by itself. The system streams video data and does not need any input from the user.

We could have the system run ssh so that we could log in periodically and apply security patches but that actually opens up a (very small) security hole. An attacker could use ssh to hack the camera. (Good luck hacking ssh).

So it is a trade off. If you honestly believe that you will never need to apply a security patch then you might decide that leaving that channel open is not worth it.

I got this idea from a presentation I attended where someone described the systems they were building for the government. The components of the system were short lived virtual machines (usually less than one day). Each virtual machine was immutable and disposable. The plan was that if they needed to apply a security patch they would just dispose of the machines in an orderly fashion and create new ones. The virtual machines did not have ssh.

The government security auditor blew a gasket and made them install ssh so that they could apply security patches. The ssh server did not provide any security value and was in fact a hole.

However, thinking about it, this (and my camera) example are just security updates through a non traditional channel.

What about

  1. a camera deployed to Mars ... everyone knows about the camera and everyone can view the camera's data
  2. a camera that exists secretly behind enemy lines (if the enemy knew about the camera, they could easily take it ... do we want to maintain a channel for security updates).
  • 2
    Even if you wish to apply security patches later on, a viable way around that would be to require physical access, combined with tamper protection.
    – Nzall
    Commented Dec 22, 2017 at 17:33
  • 7
    But the camera presumably has to upload its footage to a remote location, suppose an attacker spoofs its DNS to make it upload to the attacker’s server? And suppose there’s a buffer overflow in its network stack that the attacker can exploit with a malformed packet? Now it’s not unhackable after all.
    – Mike Scott
    Commented Dec 22, 2017 at 18:36
  • 5
    Also, the security camera accepts outside input. What if there's an exploitable bug in the image processing software that allows someone to hack your system via the camera?
    – Rob Watts
    Commented Dec 22, 2017 at 19:52
  • 3
    Good luck hacking ssh You've never been given a quote for an OpenSSH 0day before, have you?
    – forest
    Commented Dec 22, 2017 at 22:01
  • 2
    What if the vulnerability is of a nature that allows an attacker to communicate with the machine after all? It is connected to the network since it's sending data to a destination. Now you have a device that's permanently vulnerable. If your answer is, "We'll replace all the devices," then you've actually specified a "physical patching" scheme as your answer. Your points about devices now out of your control make some sense, though.
    – jpmc26
    Commented Dec 23, 2017 at 3:43

The fact that they can't think of (right now) on a way to hack it, does not mean that it is "unhackable". That is why, as a principle, we apply all security patches, even if it's on a component that shouldn't be accessible (eg. why patch a privilege escalation vulnerability if an attacker wouldn't even have user access?).

Now, they may be right, and not patching it could actually be the right decision in your case. But there are few people for which I would accept that outright. And those engineers are probably not specially knowledgeable in performing security audits.

As an argument for convincing them, I would ask them to provide access to one of these devices to anyone interested with a juicy bounty (eg. they bet their house?).

If they are uncomfortable doing that, well, then they actually don't think it's unhackable. And if they think that doing so would reveal important information, that means they rely on security by obscurity. A real unhackable system would still be hackable if the attacker knew everything about its workings.

PS: Even if they don't end up betting their houses, you would really benefit from implementing a bug bounty program.


the engineers who designed the original product feel that the machine is not hackable

The engineers who designed the Titanic felt that it was unsinkable.

The problem in IT is that people see no need to update a system, why change a working system? These companies then make the headlines: "4 factories were closed due to the x outbreak" or "Company x has been breached, the personal details of y million customers exposed".

Imagine, IBM's cloud recently moved all customers forcefully to TLS 1.1 (YES, the already obsolete version) and some customers complained ... THOSE CUSTOMERS SHOULD BE PREPARING FOR TLS 1.3, I do not know what they are doing, and I do not care what their excuses are, they should be running TLS 1.2 EVERYWHERE! IBM back peddled, UNACCEPTABLE!

Now you can tell me that the black unicorn in the stable is preventing you from moving everything to TLS 1.2, whatever, dispose of it and do not do business with the company selling the black unicorn ... We as an industry do not do this and breaches make headlines, breaches will continue to make headlines until we learn the lesson.

  • The problem is when the black unicorn in the stable is, for instance, the oldest client that brings in the most revenue. You can quit doing business with some vendor as long as they have a secure competitor, it is a completely different matter when it is a client. Also, Microsoft is stupid for not allowing you to override the TLS protocol request-wise (or even site-wise), so essentially they are exacerbating the black unicorn problem.
    – NH.
    Commented Dec 27, 2017 at 21:24
  • I am pretty sure your customer will appreciate the fact that he is compromising his security, yours, and that of other customers of yours. The News headline story is a good argument as well. Customer is king, true, but security has to come first!
    – thecarpy
    Commented Dec 29, 2017 at 16:27

feel that the machine is not hackable

Feelings do not matter. Facts do.

Go back to your risk assessment and/or threat model. Look if patching or keeping the software up-to-date was part of your risk treatment plan. Look if outdated software was part of your risk analysis or threat model.

Go back to the engineers with these facts and discuss with them how the risk changes or which threats are now untreated based on the fact that the software is no longer outdated. Also consider that this particular risk will increase over time as the chance of an exploitable defect being discovered will grow. So look ahead until the reasonable end-of-life of your product.

Note that their mitigating actions might well make the risk acceptable. But this needs to be discussed and the risk plan updated. It might also be that it makes the risk acceptable today, but in a few years not anymore. What then? Instead of looking for arguments against the engineers, get on the same page with them. Yours at least realize that mitigating actions might be needed.


“System is unhackable so why patch vulnerabilities?” In your question, you're trying to argue against a fallacy and an unprovable argument ("How do you know that it's 'unhackable'? Or do you just think that since you can't hack it, no one else can?"). In the end however, I think it's going to come down to a discussion on risk acceptability and who is willing to accept that risk. Try explaining it to them this way

"We have application white-listing so why do we need to patch vulnerabilities?"

Application whitelisting is only as good as the whitelist itself, the tools to block apps not on that whitelist, and assumes there are no faults or vulnerabilities in the application whitelisting tool itself. It also only protects against unknown / untrusted applications. What if the attacker decides to "live off the land" and use the systems own tools against itself? What if one of the applications you've whitelisted as part of the OS has a vulnerability

"We have a firewall so why do we need to patch vulnerabilities?" This is, effectively, the same argument as the previous one. Are you certain, absolutely, positively, 100%, beyond a smidgeon of doubt certain that there are no vulnerabilities in the network stack and / or the firewall itself nor any of the applications or services that may be listening or accessible via that network stack?

If their answers to the above are that they are 100% positive about their choices and decisions, then I would write up a document detailing their acceptance of that risk and have it signed off on by their leadership team all the way up to the CIO. Ultimately it's their (the CxO level) that are on the hook for the issue if and when the system gets breached and they're the one's who could be called before Congress (or whatever governmental oversight body they're subject to) ala the executives at Equifax were. When it's explained to the executives that they aren't doing everything in their power to keep a system updated and patched (as is required by many different credentialing and oversight groups / laws) and that they (the CxO) could be held accountable, attitudes oftentimes will shift.


Seems simple to me. Getting back to the question of how to get a point across in argument against not patching a system thought to be unhackable. What is the worst case scenario that can happen if that system is breached? Assume all of the protections in place fail or are likewise breached. Don't bias this exercise by discluding consequences because you don't think it can or will be breached.

Now, put that worse case scenario into business impact terms of cost in the form of lost revenues, or legal/regulatory fines, or damage to the company's image in the industry.

If that impact is severe, then look your engineers in the eye and say "are you willing to put your job -- and possibly your entire career -- on the line that this will never happen? Because if it does, in the aftermath of explaining how it did happen, the conscious decision to continue using and EOL operating system and deeming patching unnecessary will be near, if not at the top, of the list."

On the other hand, if the business impact isn't that impacting, it could make sense to continue using an EOL OS. But how to best do that in a well risk-managed way is another entire topic.


If your device has a wi-fi connection, then it can be attacked through the network. Will that attack succeed? It's a matter of the benefits of attacking the device, versus the level of effort required. Basing it on an outdated and unsupported OS definitely simplifies the attack method.

Application whitelisting is no protection, just a minor roadblock. You think a hacker can't develop an app that masquerades as one on the app whitelist? Of course they can... something they might look into if their first attempt doesn't run.

Equifax had quite a firewall in place. Didn't stop the hackers from exploiting the Struts hole that Equifax IT managers failed to patch, through a port that was left open out of necessity. A firewall just stops some of the older, obvious attacks.

Think back to the Target hack - the CEO and CIO lost their jobs over that one, and it was perpetrated by an insider, aided by Target's use of an older Windows version, no longer being updated, plus older, non secure connectivity methods on their point of sale devices. Doubtless, the CIO concluded that updating the Win version on their POS devices was too expensive, a judgment that was proven to be very wrong.

Think embedded firmware is immune to hacking? Consider the HP printer hack. HP had the clever idea of updating its printer firmware through a print job - easy to initiate. Until... someone came up with a firmware version that turned the printer into a spam relayer, and delivered it via a malware print job.

How do you do firmware updates? Through wi-fi? Yes, a hacker can replicate that... if they have a good enough reason.

A networked device can be hacked into becoming part of a botnet... a common way to launch a DOS attack. A hacker could find the vulnerability, and knowing that it would damage the company reputation, launch the attack at the same time they're shorting your company's stock. That has happened... Stealing PII and CC info isn't the only way to profit from a hack.

Now, ask yourself - what is the risk to you personally? If your system were to be hacked, can you demonstrate to the executives of your company that you exercised due diligence in identifying and mitigating potential threats, especially since you are basing the system on an OS that is no longer being updated? Hint: taking the word of engineers that say the system is 'unhackable' probably doesn't qualify as due diligence.

For that matter, if your engineers say it's unhackable, they probably aren't even looking for potential vulnerabilities, let alone mitigating them.

Anyone who says a system is unhackable just isn't being realistic. Not in this day and age.

  • You've made reference to an awful lot of historical examples. Some links would be good.
    – Wildcard
    Commented Dec 29, 2017 at 4:11

This may not be a technical decision at all. Using any externally-sourced component generally means you have to use that component strictly in accordance with its manufacturer's guidelines, or risk being stuck with all the consequences and liabilities arising from any failure it might be implicated in.

So if the device misbehaves, and someone is injured (or some other liabilty is incurred) then the original OS maker will say "unsupported software - not our problem". And your company's insurer will say "using out-of-support antiquated software - that's negligent, and so not our problem".

So, from your personal perspective, make sure those making the affirmative decision to continue to use outdated, unsupported components:

  • have been shown that they are doing so (and you have that in writing)
  • have affirmatively made the case that the upgrade is unnecessary (and they've made that in writing)

There's a big gap between people saying "we don't need to do this upgrade" and "I personally accept responsibility for not doing this upgrade".

In practice, there are often upgrades to components that are mandated by them having gone EOL, even if there's no actual technical needs to do so. That's a necessary part of engineering a complex product.


Depending on the resources available to you the "fool proof" (with all due respect to your colleagues) way would be to prove to them that the system is hackable. Hire somebody who can, and let him or her demonstrate the system's weaknesses. My guess is that with WLAN it should not be terribly difficult. WLAN and firewall? That's a contradictio in adjecto.

Afterthought: Perhaps it's possible to agree on payment on success (my dictionary calls that a "contingency fee"); that way the (hacking) service would always be worth the money.

  • And then they simply mitigate those weaknesses and have no need to upgrade the OS...
    – schroeder
    Commented Dec 26, 2017 at 16:25
  • @schroeder Some of them will be in the OS (IP stack, encryption etc.) Commented Dec 26, 2017 at 16:28
  • yes ... and they can be mitigated ...
    – schroeder
    Commented Dec 26, 2017 at 16:29
  • @schroeder Well, you can start rewriting the OS, yes. You can also curtail the functionality, e.g. restrict connectivity. Commented Dec 26, 2017 at 16:31

Each and every day we have headlines saying some system is hacked. It is not because they are neither up-to-date nor not protected with machine guns but because someone is investing time to hack them.

Most importantly, those that are well played are not done by IQ power but simple social engineering. So we are told to keep the system up-to-date because if we somehow fell into that pit hole we give the info that doesn't help them.

  • 1
    This does not answer the question. The engineers are mitigating the problems. If they are, why update the OS to a later version?
    – schroeder
    Commented Dec 22, 2017 at 19:52
  • @schroeder As I mentioned earlier we do to protect the hardware from both insider and outsider intrusions as mentioned the question outward facing patches protects outsiders as they didn't know what was patches already but admin know what has been done to secure it and if he himself want screw the employer its easy for him to do so that's the reason why third-party security checks are made to avoid such disasters Commented Dec 22, 2017 at 20:44
  • 1
    It's impossible to mitigate a completely unknown risk.
    – barbecue
    Commented Dec 24, 2017 at 23:53
  • Upvoted for mentioning social engineering attacks. Vulnerabilities can be to social attacks as well as automated ones.
    – barbecue
    Commented Dec 25, 2017 at 0:31

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