Tag Archives: Privacy

Dutch GGD claims survey to be anonymous, but it’s not

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The Dutch healthcare organisation (GGD) is an organisation funded by the Dutch government that is concerned with the health of people in the Netherlands. They want to know about the health of people in the province of Gelderland, so they decided to start a survey.
I agree, statistics, like from the Dutch statistics bureau need to come from somewhere, and in this case it is important they get it from a very diverse an relatively large population.

How it works
So how does the GGD do that? Well, they first they send you a letter with login data. You can login on their website (not using SSL!) using a predefined code and you are ready to fill in the survey. And to be certain you didn’t forget, they send you the survey on paper, so people with no access or know how of the Internet can complete the survey as well.

Sensitive information
The questions they ask you are about your birth year, marital status, education, health, alcohol use, smoking, drug use, eating habits, social environment, violence at home and your work. A lot of sensitive information, some of which you probably don’t even voluntarily tell to your doctor, unless absolutely necessary.

Anonymity
Of course, you don’t have to be afraid that the data you fill in is connected to you as a person, because they offer you to conduct the survey anonymously. So, the GGD offers you a way to keep your privacy. They intent to do this by allowing you to rip off the first paper of the survey before sending it to them. Well ok, I ripp off the first page and my privacy is guaranteed. But then I started wondering what all the the bar codes and identification numbers are doing on each of the pages? (take a look at the first survey page snapshot below)

Anonymous or not anonymous, that’s the question
The thing that really scares me about this survey is the fact that they lie to the participants. This is not an anonymous survey, at least not to my definition of “anonymous”.
They GGD even mistakenly proofs to you that their survey is not really anonymous. How? Because they recently sent me a letter asking why I didn’t fill in the survey. Err wait, I could have submitted it to them anonymously (remember), so how could they possibly know I didn’t sent it to them or filled it in online already..? That’s the point. If it was really anonymous, they shouldn’t have known whether I sent them the survey!

My opinion
I think the GGD screwed up. Not because their survey was bad, nor is their intention to conduct this survey, but solely because they claim that it is anonymous, which it is certainly not! If they ever want to gain my trust again, or even receive sensitive information about myself, they should define what they mean by “anonymous” and provide a proper and clear privacy policy. Lying is not a good basis for gaining consumer trust.

References (the letters)

Vodafone voicemail uses caller ID for authentication

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This article is about a security risk that I found while using Skype and Vodafone voicemail. In this article I will dive into a specific situation concerning the security of one’s Vodafone voicemail (Netherlands) in combination with Skype‘s ability to spoof the caller ID. Besides that I look at the main concern: trusting a caller ID for authentication purposes.

Vodafone voicemail and Skype

The problem is simple. Vodafone NL offers their customers a voicemail service. If you call the voicemail service from your own mobile phone, you get direct access to the voicemail inbox without needing any form of authorization. It seems the mobile’s caller ID is used for authentication.
Skype, on the other hand, has a ‘feature’ that allows you to assign your own mobile number as a caller ID for Skype-Out calls. This means you can spoof your caller ID, if you authorize it with Skype, for which you only need to respond to an SMS sent to the device once.

So, if I could trick a victim into lending me his/her mobile for only 5 minutes, I could abuse that moment to register the mobile number with a Skype account. This would allow me to access the victim’s Vodafone voicemail, because Skype allows you to spoof the number, and Vodafone authenticates you to a voicemail box based on the caller ID. So, I only need my Skype account to access the victim’s voicemail. An even simpler method could be by using a service provider that allows me to spoof a mobile number, like SpoofCard claims to do. You would then only require the victims mobile phone number. Scary!

Other services at risk?

So Vodafone voicemail (NL) is vulnerable for this “hack”. But what about other service providers that rely on the caller ID?

For example the ‘ABN AMRO Saldo voor de iPhone‘ [iTunes], a banking applications for the dutch ABN Amro bank that allows you to see your bank account’ balance (requires a 4-digit PIN).
Or what about the ‘Rabo Bankieren‘ [iTunes] used for banking with the dutch Rabobank that only requires a 5-digit PIN to see your bank account’ balance?
By circumventing the caller ID as being part of the authorization of these applications, the only security layer left is a 4 -or 5-digit PIN code, which IMHO is not enough any more.

Of course, the same principle applies to SMS text messages, like described in the article Twitter and Jott Vulnerable to SMS and Caller ID Spoofing by dhanjani.com, but for the sake of simplicity I will not go into that right now.

Questions and conclusion

So what do you think?

  • Do you think this is a security risk or not?
  • Is the caller ID something that is easy to fake?
  • Why is Skype allowed to spoof the caller ID? Is this something anyone can do on any phone network?
  • Should service providers be allowed to trust the caller ID for authentication purposes?
  • Have you seen service providers using the caller ID for authentication purposes?

In my opinion trusting the called id for authentication purposes imposes a security risk. Developers should be aware that trusting a caller ID should not be an authentication method solely by itself, but always as an addition to another. In my opinion, service providers should not use the caller ID alone for authentication!

And remember, if Paris Hilton can hack into a voicemail, anyone can! ;-)

Update 24-03-2011: I merely used the examples of the ABN Amro and the Rabo Bankieren application as an example to think deeper about security and privacy concerning the use of these (very handy!) financial applications, but its clear that they do not rely (and probably also not even send) the caller ID to the bank’ server, so a probable risk with using the caller ID as authentication for these applications is irrelevant.

Issues with Dutch cable provider UPC

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UPC unhappy logoUPC is a service provider for Internet, television and telephone in the Netherlands. I don’t like UPC and I’m going to tell you why. If you are not interested you can stop reading now, but I need to get this of my chest.


Why UPC is a bad service provider (in random order)…

  • Since recently, UPC forces non-resolving domain requests to their default(!) DNS servers with a request that resolves to a web page that 302 http redirects you to their own “search” engine. So if you mistype a domain name, your browser redirects you, thereby invading your privacy and providing you with their full-banner “helper”-webpage. This is against the DNS protocol.
    You can solve it by forcing your IP’s to use another set of DNS servers. For me this means I have to manually configure each network device because I cannot make my Thomson router distribute specific DNS host adresses via DHCP :(
    This site tells you more about the solution where you have to manually set your DNS servers.
  • I have a ‘royal subscription’ which means I get nine HD (High Definition) channels for 10 euro/month extra. UPC offers you another feature with this Royal subscription that is called Video On Demand (VOD). The feature is nice because they provide you with a lot of nice content (like series) that are watchable on demand, just like a dvd.
    The problem is that it  often doesn’t work for me, giving me a VOD 103 exception. I’ve contacted support three times now about this issue and they still haven’t manage to locate the problem. Every time I have to convince them my signal is ok (using a special test-channel). The problem is probably caused due to a under capacity at their streaming servers, but people at the support desk simply follow protocol and never find the problem so it never gets fixed.
  • I have a subscription where I have a combined box for telephone, internet (24 MBit) and (HD) television. I don’t want the phone, but I cannot just order only internet and television. I don’t want to pay for this crappy phone line that doesn’t allow me to dial +31(0)87 numbers (voip phone land-lines in the Netherlands). Another irritating issue is that when your broadband cable modem has no connection, people calling your number get a normal “phone is ringing”-tone on their side, and not a “number not reachable”-tone, which doesn’t help finding the problem.
    Besides that UPC tries to sell this product as a normal phone line, but instead it’s a very error-prone telephone line that you should not primarily rely on when you might need to call the alarm-number.
  • My (brand new) black colored ‘Media Box’ that provides me with HD television seems unstable. Sometimes – out of nothing – the screen just turns black, while sounds continues. Remote control activities don’t work any more and the device get’s locked. In this case the device needs a power-cable off and on, which costs me at least 60 seconds before the television get’s back. Not funny when you were watching ‘time shifted’.
    I’ve also seen issues where the device automatically switches to the (of all channels) interactive ‘UPC’ channel, functionally “disabling” the number pad on your remote control so it will take you some time to get back to the non-interactive TV channels, while losing ‘time-shifted’ data as well. The remote control is not the problem (I’m using the Logitech Harmony nowadays), and there are numerous people on forums complaining about issues with the UPC media devices as well.
    I’m silently hoping they push a ‘all-problems-fixing’-firmware update soon.
  • UPC poisons their DNS servers with a blacklist so they can block domains hosting child pornography. The problem with this is that they are not open about it, so they they manipulate your DNS requests without telling you about it. I wrote an article about that case specifically.
  • The Internet connection UPC provides is slow during evening hours and has connection dropouts very often. When I switch my Internet connection to another provider to check if it’s a local network issue, the connection is always back and better.
  • With my subscription, they do not allow me to pay ‘manually’ with so called ‘accept giros’, instead they forced my to use automatic credit payment where they are in complete control. So if they make a mistake, It’s up to me to get the money back. Isn’t this against the law?
  • UPC violates your privacy. When you keep your default password, they get it in clear text on their screen at the help desk. If you play it nice, they’ll tell it to you. This endangers your privacy because it is the password that is also used for the mail account they offer you and provides you access to their service center where you can order new services as well. Don’t use their mail account if you  are concerned about your privacy.
  • Something positive on the contrary is that they offer a very fast internet connection for almost the same price as you were already paying, an action that was just launched recently. The disadvantage of this is that their network gets more load, something that could explain the continuous connection drop-outs I’m continuously experiencing. They don’t seem to be prepared for Internet speed upgrades with their network.
  • When you call UPC on their special 0900-number, they charge a high price, especially when calling from a mobile phone. When you telephone line from UPC is dead, you cannot use their phone, so you are mostly stuck to a mobile phone.
    The high calling rate is not fancy, but I find it quite ok, because it prevents the waiting time due to customers only calling when they really have to. Still, their waiting time on average is too long, in my experience (> 5 minutes average).
    Besides that, when you call them, it takes you at least 2 minutes before you get through their menu, every time. Sigh.
    A refund for callers – if the problem is theirs – would be nice.
  • You cannot quit your contract with UPC whenever you want, you are stuck with them for at least one year. It’s not only UPC that plays this trick on you, there are other providers that do this to you as well.

So why do I still use UPC?

The reason for me still using UPC  is that they are the only provider offering HD television to my home. Besides that my ADSL line doesn’t seem to be capable for high speed Internet access (meaning 8 MBit+ downstream), and I want a reasonable upload speed as well.

If there is another provider for my region available that includes HD television and fast internet access, I’ll switch immediately.