Friday’s DDoS: Assisted By Poor DNS Configuration

 Computing, Security  No Responses »
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

Internet Censorship By Denial Of Service

 Computing, Security  No Responses »
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

Anti-Virus Is Dead. Long-Live Behavioural Analysis …

 Computing, Security  No Responses »
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

 

 

Let’s Encrypt!

 Computing, Security  No Responses »
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.

Random Thoughts on the Draft #IPBill

 Computing, Politics, Security  No Responses »
Nov 042015
 

The draft #IPBill or more conventionally the draft of the upcoming Investigatory Powers Bill. And some random thoughts on it …

First of all this is not really anything new, as this bill wraps up and modifies existing legislation regarding legal "snooping" in the UK. Whilst it is sensible to pull in multiple existing bills and incorporate the powers in just one place, it makes it a lot harder to see what is new.  There could well be new draconian powers in this draft bill; in fact there probably are, but it is hard to see just what is new.

And there are few people I would rather trust less in drafting such a bill than Theresa May. 

It is worth noting that the most draconian powers under this bill are not new; in fact once we analyse it properly it may be that there is very little that is really new. 

Oh! And just to state the obvious: Ignore the spin at the beginning; it's the easiest section to read, but may be somewhat deceptive (either deliberately or because it over-simplifies matters).

There are new protections against abuse in this draft bill – specifically the Judicidial Commissioners who will sign off on warrents if they feel they are justified. However how much protection does a current or former High Court judge offer? Well one that co-operates with the government by reflex isn't going to be much help. We need one that is suspicious of government and protective of individual rights.

And there's an escape clause – an "urgent" warrent can be approved without a JC, although it only lasts for five working days rather than six months. Of course the JC gets to approve it (or deny it) after the fact, but this turns this protection into a fig-leaf. And of course the "national security notices" have no oversight before they are issued.

The other thing that occurs to me: What is the difference between a public telecommunications provider and a private telecommunications provider? I dare say that most people won't know when they connect to a network which they're on. And there are different provisions depending on whether the network is public or private – as an example it would be legal for a private telecommunications provider to intercept. 

The purpose behind the #IPBill is supposedly to combat serious crime and to defend the "national interest" in security matters, but some of the provisions allow for economic considerations to be taken into account. So the government plans to sell our communications data to interested parties? Perhaps that's not what they intend, but it doesn't look like there's anything to stop them.

It is interesting to note that local authorities are specifically excluded from certain provisions – they of course are well known for taking previous instruments, and using them for purposes other that what was intended.

MP's have extra protection under this bill, and people are somewhat cynical about the reasons for this – perhaps thinking it's to protect Theresa May's porn browsing habits (Ew! I think I just threw up in my mouth just a bit). Actually, in theory it's not entirely unreasonable when you think of it as a measure to protect the privacy of the MP's constituents who may be discussing privileged information with their MP.

Of course that very quickly dies a death when you look closer at the list of MP's that are protected – all the MP's from the national parliaments, plus MEPs from UK constituents. If you raise a matter with your MEP, she may very well suggest speaking to another MEP – such as the MEP from from somewhere other than the UK if they happen to be the rapporteur (yes Dave, I finally remembered) for a particularly specialised subject area.

There is a fair amount of wordage within the bill dedicated to keeping warrents and retention notices secret – disclose such the existence of such things and you're looking at gaol time. I can see the argument for why such notices should be secret – for a certain duration, but they should be made public eventually so that their use can be judged in the court of public opinion.

Undoubtedly I'll think of additional points to make as I get further into the bill …

 Older Entries  Newer Entries