Ben Laurie blathering

26 Jun 2009

Who Pwns The Internet? (Take Two, Part Two)

Filed under: DNSSEC,Security — Ben @ 6:20

I actually got these done over the weekend, but I’ve been kinda busy. After taking a more, ahem, principled approach, France seems less dramatic

France by AS

but still pretty impressive. If you take a close look you’ll see I’ve also had a crack at adding the AS’ owner as well (not 100% reliable, if anyone knows how, let me know!). The UK depends on one less AS than before

UK by AS

and I can do Fiji

Fiji by AS

I still can’t do the world, though – but now the problem is that dot chokes on the graph.

20 Jun 2009

Who Pwns The Internet? (Take 2)

Filed under: DNSSEC,Security — Ben @ 20:08

Another interesting way to pwn the Internet is to control the routing of packets to critical nameservers. In practice, Internet routing is done by ASes (Autonomous Systems). If an AS wants to pwn a nameserver on a network it controls, it is a trivial matter: it just redirects the packets to its own nameserver. I’d draw you a picture, but I’m sure Matasano Chargen will do it prettier.

So. I thought it would be instructive to determine which ASes had control over which domains. More fun with dot.

The picture is no longer quite so rosy for the UK, but still, not bad, all things considered.

UK's AS dependencies

But France. I don’t know what to say about France. France is surreal. I’ve linked through to a much bigger version because, well, you’ve got to lose yourself in the spiderwebs. The SVG is here, though.

Small version of France's AS dependencies

As for Fiji, I’d love to show you Fiji, but the way I’m doing it doesn’t work for Fiji right now. And hence, obviously, not for the whole world, either. Coming soon, I hope.

14 Jun 2009

Who Pwns The Internet?

Filed under: DNSSEC,Security — Ben @ 16:22

Update: Ben Hyde suggested I should use the (undocumented) “concentrate” option to dot, which certainly tidies up the graphs. So I did.

A remark on the IETF DNS Working Group’s mailing list got me thinking.

Suppose I were the owner of (to pick an example at random), then I could take control of, for about 25% of Internet users, since one of their four nameservers is Similarly, I could then take control of for 25% of those 25% (via One in seven of those guys could fall victim to my ownership of via, and from there I have complete control of fr (that is, France) – ok, by now, for only a bit under 1% of the Internet, but even so, that’s kinda worrying, don’t you think? And obviously if I own then it would be more like 3.5%…

On the other hand, uk does not suffer from this problem: it depends only on Which seems like a much better idea. Anyway, I got to wondering just how bad this problem actually is, which led to me having more fun with dot. So, for a taster, here’s France’s dependencies…

France's dependencies

And here’s the UK’s

UK's dependencies

And here’s Fiji (I include this for Jasvir, who is getting married there soon, and ought to know the terrible risk he’s taking)

Fiji's dependencies

And all the top level domains put together

All TLDs' dependencies

So that one is pretty but a bit hard to digest. Obviously the main news is that there are a lot of domains which could interfere with one or more TLDs!

Another way to think about this is to wonder who could pwn the most TLDs? Well, the answer (after the root, of course) is that,, com and net come in equal first with 228 TLDs pwnable. Next up is Affilias, through a variety of domains, including org and info, able to control 187 TLDs. After that comes se (Sweden) with 158 and,,,,,, edu, no,, and, all able to have a go at 157 TLDs.

Food for thought. Especially if you’re thinking about DNSSEC.

12 Jun 2009

Ignorance Transfer Network

Filed under: Programming,Security — Ben @ 12:41

SSDSIG recognises that some commonly used languages (e.g. C, php etc.) allow, or even encourage, programming practices that introduce security vulnerabilities. Accepting that in time market forces may encourage the adoption of safer alternatives some members feel that the process needs to be accelerated. The reasons for the continued use of ‘unsafe’ ‘languages and the near-term feasibility of alternatives for commercial systems of modest criticality are complex and ill-understood. This also applies to the slow uptake of more formal methods Further data on this is required.

This is a gem from “Secure Software Development – a White Paper: Software Security Failures: who should correct them and how” by Bill Whyte and John Harrison, from the Cyber Security Ignorance (Knowledge, shurely? Ed) Transfer Network, presumably at the taxpayer’s expense. I hear through the grapevine that they’re planning to spend more of our money to set up a “Secure Software Development Panel” to deliberate on the deep thinking exemplified above. Awesome.

So, what’s wrong with that statement? Firstly, I think we’ve got past the idea that there’s something extra special about buffer overflows as a security issue. Yes, there are many languages that prevent them completely (e.g. PHP, amusingly), but they don’t magically produce secure programs either. Indeed, pretty much all languages used for web development are “safe” in this respect, and yet the web is a cesspit of security problems, so how did that help?

Secondly, the claim that the “reasons are … complex and poorly understood” is a great one to make if you want to spend your life wasting your time on government money, but, well, not exactly true. C is widely used because it is fast, portable, can do anything and has a vast amount of software already written in it that is otherwise difficult to get at. Which is, of course, why PHP is widely used: because it’s one way for the less capable programmer to get at all that C out there. As for “near-term feasibility of alternatives”, well, name an alternative and I’m pretty sure anyone knowledgeable in the field could give you a thorough rundown on its near-term feasibility in an hour or so.

Thirdly, talking about “unsafe” languages implies that there might be “safe” ones. Which is nonsense.

Fourthly, formal methods. Really? The reason there’s slow uptake is because they don’t work. Get with the program, guys!

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