Nov 262016
 

(actually we don’t usually sit in the data centre; it’s too noisy and usually the wrong temperature for people)

There is a perception amongst people that security “gurus” who work in network security are spying on all your network traffic. Not the hackers (which is a whole other matter), but the people who run enterprise firewalls. We do, but we’re not interested in what you are doing but instead what is being done to you (and the enterprise as a whole).

Frankly nothing strikes me as more boring than spying on someone’s porn browsing – if I really need to, I’ll hunt down my own porn thank you very much! And we’re busy; you could probably double the size of every network security team in every organisation on the planet and still nobody would be sitting around twiddling their thumbs.

On the subject of porn (as an extreme example), it is not a security issue. There is an argument that browsing porn sites is putting yourself at greater risk of picking up some kind of nasty infection, but avoiding porn sites to avoid getting infected with malware is a tactic that results in your computer being infected. So the intended content isn’t a problem as far as security is concerned, but we’re interested in unintended content.

Now there are places that enforce browsing censorship – blocking anything that isn’t work-related. That role is usually dumped on the network security people because they have the tools to do the job.

Does porn browsing on the office matter? Of course it does – some people are upset by the sight of such things, and almost as important, when someone is browsing porn they are not working. But such matters are best dealt with in the office by the line manager – if someone isn’t doing their work it doesn’t matter if they are browsing porn, hitting Facebook, or snoozing under the desk. All should be dealt with appropriately by the line manager.

And centralised censorship is a rather clumsy tool – blocking Facebook is all very well if it is to prevent personal usage of the Internet, but what about the Marketing department using Facebook for publicity? Or the Customer Service department keeping an eye on Facebook for product problems that they need to look into? These can be allowed through on a case-by-case basis, but it highlights that censorship is a clumsy tool.

The word from a nameless vendor who is in this space, is that in many cases this censorship has less to do with preventing people from doing “naughty” things, and more to do with controlling bandwidth usage. And as bandwidth becomes cheaper, there is less interest in censoring Internet activities – certainly from a personal perspective I notice a decrease in the number of people who complain they cannot visit certain sites because of work’s “firewall”.

There is also the subject of TLS inspection where firewalls intercept and inspect TLS or SSL encrypted traffic between you and “out there”. Again there is a suspicion that we are for whatever reason spying on your activities. The answer to this is the same as previously – why should we bother? It is too much like hard work, and frankly most of the information that passes through a firewall is unbelievably boring.

No, TLS interception is used to do the boring task of inspecting traffic for malware, spyware, and other security threats. And with the increasing use of TLS to encrypt traffic it is becoming more and more important to do TLS interception for security reasons.

Yes there are those who would use that sort of technology to spy on your activities, but those organisations are typically nation states … and repressive ones at that. But it is extreme foolishness to blame a useful tool for the abuses that an abusive government perpetrates.  Your average enterprise just isn’t that interested in what you’re up to.

And if you still don’t believe this, there is a simple answer: Do anything private on your own private network.

b84v37631-cubist-eye

Oct 222016
 

Yesterday lots of people found the Internet disappearing on them due to a significant DDoS attack against the DNS infrastructure of one company. Now there are all sorts of suggested fixes for this sort of problem, some of which are useful.

However it is notable that people have not mentioned one method built into DNS which could have been used more effectively. Indeed one suggestion was for the DNS to do something it already does – caching.

When you ask your ISP’s DNS servers to resolve a name such as example.org, the answer that your ISP’s DNS server gets back contains several bits of information in addition to the answer you are interested in (the IP address to connect to). One of which is how long to cache the value for, which means that your ISP’s DNS servers can save themselves some work for as long as they are allowed to cache the answer for.

Now it is awfully convenient to set this value to something like 5 minutes because if you have a need to change the value, it is nice to have the value change as quickly as possible.

But it also increases your vulnerability to a weaknesses in the DNS infrastructure.

If you increase the time-to-live (TTL) value to something more like 24 hours, then your DNS servers (or more usually the DNS servers of your DNS service provider) are required less frequently which means that if something takes them offline for any reason then there would be a decreased impact. It will still stop some people from getting the DNS answers they need, but the proportion unable to get an answer will drop dramatically.

 

damascus-dns

Sep 282016
 

One of the things that has happened recently was that a commentator on security matters (Brian Krebs) was taken offline by a massive denial of service attack, which (not so) mysteriously happened after he published an article on denial of service attacks. The short version of the story was that his site was hit by a denial of service attack totalling approximately 650Gbps (that’s roughly 6,000 times as much network bandwidth as your typical broadband connection), when his denial of service protection threw their hands up in the air and said: “That’s too much like hard work for a pro-bono service” and gave him 2 hours to move his site.

Google helpfully provided an alternative with Project Shield, and the site was reasonable quickly available again. And to be fair to the original denial of service attack providers (which I’m not naming), this level of attack was sufficient to cause problems to their paying customers and protecting from this level of attack is very expensive.

And indeed paying for denial of service protection is very expensive; the income for the entire lifetime of this blog site would pay for approximately 2 hours of protection. If that.

There are two aspects to this attack, although to be honest neither are particularly new.

The first is technical. Most distributed denial of service attacks are quite simple in nature – you simply ask a question of a dumb “server” with the return address of the site you want to attack. If you send out enough questions to enough dumb “servers” (which can actually be simple workstations or even Internet of Things devices), then you can overwhelm most sites on the Internet.

There are two fixes for this :-

  1. Don’t run dumb and insecure servers.
  2. ISP’s should stop allowing people to forge addresses on network traffic (Ingres Filtering or BCP38).

The second fix is the simplest method, but given how successful the decades long campaign for ISPs to do ingres filtering has been, tackling both ISPs and dumb servers is worthwhile.

As this latest attack may have been chiefly by IoT devices simply sending requests to the victim, the implementation of ingres filtering may not have been of much use in this case, but it is still worthwhile – this attack is not the only one that is happening. Attacks are happening constantly. However, tackling these “dumb servers” that were controlled by the attacker is also a priority, and we need to start seeing concrete action by the ISPs to tackle their customers’ mismanaged networks (home networks in many cases) – aggressive filtering of infected customer networks, and customer notifications that include advice.

Of course ISPs are not going to like doing that just as IoT manufacturers don’t like paying more to make secure appliances. Well, it’s time to name and shame the worst offenders; the bad publicity may help to counteract the lack of incentive to invest in processes that don’t immediately help the bottom line.

The second aspect is rather more serious. We now have an Internet where it is relatively easy to silence anyone who says something you do not like – if you’re rich enough to hire a denial of service gang. Anyone that is who cannot afford protection from such gangs, and there are suspicions that some gangs also provide denial of service protection services.

And this story is not the first time it has happened, and we need to start thinking about mechanisms to keep smaller publishers online when attackers try to censor them. Unless we want all our media controlled by the big players of course.

2016-03-28-swamped bandstand.small

Jul 142016
 

One of the throw-away statistics I tripped over recently was that there are 5 new malware releases every second.  Now many of those new releases are variations on a theme – there are pieces of software designed to distort a piece of malware into a new piece of malware with the same functionality. This is done deliberately to evade anti-virus software.

And it works. Every so often I feed some strange mail attachments into virustotal to find out how widely it is recognised. It is not uncommon to find that only 2-3 will recognise it as malware out of 50-odd virus checkers on that site. So if you happen to be dumb enough to download and activate the attachment, your anti-virus checker has a roughly 5% chance of protecting you.

Not exactly what you should expect.

I recently sat through a sales pitch for a not-so-new corporate product that does anti-malware protection very differently. Of course it is also insanely expensive, so I will not mention the actual product, but it does offer something new. Protection against malware by checking and blocking behaviour.

Whilst they add all sorts of clever data analysis tricks, fundamentally anti-virus products recognise malware because they recognise the data that makes up the malware. If they don’t recognise the signature of the malware, then they do not know it is malware; so they have an incredibly difficult time recognising new malware releases.

But recognising malware based on behaviour is far more likely to successfully recognise malware – for example by recognising an attempt to make itself persistent in a way that an ordinary application does not do, and blocking it. Which is a far more practicable method of blocking malware (if it works!).

It is also something that should probably be built into operating systems, which to a certain extent already has been.

The New Defence

The New Defence

 

 

Jan 312016
 

Thanks to the Let’s Encrypt project, my blog now has a trusted certificate and traffic to it is encrypted.

Rusty_Padlock

Of course there is nothing especially private about this blog, so why encrypt?

Well for one thing, by encrypting those who log in can keep their account details private.

But for the overwhelming majority of visitors (who do not log in) all it adds is a bit of privacy. Snoopers still know that you are visiting a dodgy website lurking underneath my stairs, but they won’t know what lurid posts you are reading.