Exclusive Interview: Hacking The iPhone Through SMS

Explaining The Vulnerability, Continued

Alan: What about push notifications and visual voicemail? Don’t those rely on SMS?

Charlie: Not sure about the push notifications, although that would make sense. It does use SMS to alert when new voice mail arrives, as well as indicating where the phone can pick up the actual sound files. It also uses SMS as notification of MMS messages.

Alan: So potentially, the push notifications or new voicemail arrival have “magic strings?" Couldn’t a malicious hacker direct the iPhone to pick up a forged voice mail with sound files from somewhere else?

Charlie: It is not that they have magic strings, but rather that SMS is more than text messages. It can be used to transfer data as well. Some carriers use it to send ringtones and OTA updates, for example. There is a byte in the header in the data that tells the device what kind of data it is, and the device knows how to handle different kinds of data. The concatenated messages I spoke of earlier have this “identifier” byte set to 00. Normal text messages don’t even have this data header. Another type of data indicates the number of voice mails that are waiting. Finally, a different type of data (one destined for a particular SMS “port”) tells the phone where to get the sound file. This also explains why I can send 500 messages and you don’t know about it. They are all “data” SMS messages and so your phone doesn’t display them to you since they are not simple text messages.

Many people wanted to know how to disable SMS when this bug came out. In most cases, you cannot disable them because SMS is a core feature of the phone, and the carriers rely on it for much of the functionality you depend on.

For testing, I tried to have the iPhone pick up a sound file from my Web server, but apparently the AT&T infrastructure will only allow it to pick up this file from their servers.

Alan: In your opinion, had Apple audited the code for security, should they have caught the bug?

Charlie: Umm...bugs are hard to find, which is why people pay me to look for them. This bug wasn't obvious by any means, and it was the only one I found while performing a moderate fuzzing effort, so I guess I can't fault them too much.

Alan: Seems like there are themes to security though. Programmers get trained to think about the boundary cases when debugging or malformed user input, but I think a lesson learned here is that the interaction between different modules is important to consider. What’s been the reception to your “No Free Bugs” campaign?

Charlie: Mostly silence. Some people have written with support, but mostly no one talks about it. It’s probably mostly my fault because I'm terrible at organizing things, and I am very busy with work and research, so haven't put any time in it. I still think if vendors paid, more people would look for bugs. This SMS stuff is a good example. Between us, Collin and I found one bug in iPhone, Android, and Windows Mobile. Then we stopped testing. We had enough for our talk, what motivation did we have to keep looking? This is really an unpaid hobby for us, so we do the minimum level of work possible to get results good enough for conference presentations. If researchers were going to get paid big bucks for these bugs, they would look and find them.

As another example, I'm not looking at SMS bugs anymore, I'm moving on. That is what researchers do now. Why would I keep looking for these extremely dangerous bugs? I won’t get paid and since there were a rash of SMS talks at BlackHat, conferences won’t be interested in them for a while. That is really what “No More Free Bugs” is about--motivating skilled researchers to look for bugs. Bad guys are already motivated by the financial gains they stand to make and will continue looking for these powerful bugs.

Create a new thread in the US Reviews comments forum about this subject
This thread is closed for comments
Comment from the forums
    Your comment
  • burnley14
    Wow, don't make Charlie angry. He can take over your phone remotely and kill you with it.
  • ethaniel
    Unless he hacks Chuck Norris's iPhone. That would be the end of him. :P
  • ossie
    As usual, mr. Charlie "no more free bugs" just likes to overemphasize his findings - free advertising is always great - but it seems his greediness isn't finding the proper nourishment (read cash from blackmailed manufacturers).
    Crashing an equipment is one thing (getting easier in these days of consumerism induced fast paced "innovation"), but taking it over is in a whole different lot.
    Why didn't he demo the iPhone takeover code at BH? I'm sure he would have liked to really impress the audience, but, as it needs a lot of very careful setup, the chances for failure would have been way too high. There are a lot of unexpected events which could have taken place in a real environment (read through the network), as opposed to a laboratory environment (frame injection without external disturbance), which would impede the "golden sequence" to reach it's victim in the desired way (out of order message delivery is just one, which comes quickly to mind).
  • downer88
    ethanielUnless he hacks Chuck Norris's iPhone. That would be the end of him.

    Chuck Norris doesn't use a phone, he uses his "outside" voice!

    Seriously, no offense but I though mobile phone exploits were nothing new.
  • Anonymous
    This should be considered a nice and very credible rebuttal to the ridiculous interview with Joanna Rutkowska... Charlie is a real security expert, and he says Mac security sucks. Take note, Apple fanboys.
  • steiner666
    downer88Chuck Norris doesn't use a phone, he uses his "outside" voice!


    and of course "jailbroken" iphones couldn't take down a network, how stupid must ppl really be to believe Apple/AT&Ts shit
  • anonymousdude
    Charlie_FangirlThis should be considered a nice and very credible rebuttal to the ridiculous interview with Joanna Rutkowska... Charlie is a real security expert, and he says Mac security sucks. Take note, Apple fanboys.

    The safety of a Mac lies in its market share. Less market share less atacks,viruses,trojans, etc. That's why people using linux hardly ever have a problem with security.
  • Anonymous
    anonymousdude: Linux has all but idiot-proof security, low-level exploits are very difficult, there are package repositories that have everything you could ever need without resorting to potentially untrustworthy 3rd party downloads, and they were doing Microsoft's UAC long before Microsoft, and far better and less annoying. Not to mention, they have a far better scheme for handling execute bits and possible remote execution of arbitrary code. An OS is only as good as the idiot who's using it, but Linux has done by far the best job of idiot-proofing an OS, if it hits 99% marketshare, it will still have a fraction of the problems Windows and OSX do, and there are viruses for OSX, ask Apple who recommend MULTIPLE antiviruses be installed on Macs. Out of tens of thousands of free, open source Linux packages, there are hardly any antiviruses or firewalls even available for Linux, because it is actually for real, not necessary. No shit...
  • Anonymous

    OS X is built on UNIX the same as Linux. Please do some research before you spout about things you obviously no nothing about. Otherwise quite wasting the time of everyone that reads the comments.

  • Anonymous
    rorosdad: Obviously you know nothing about UNIX or Linux or the inner-workings of OSX. UNIX operating systems follow a standard called POSIX. There is quite a bit of room for differences in how they are implemented. The BSD kernel OSX stole is not the same kernel that Linux uses, besides, most of the security doesn't necessarily happen in the kernel, user interaction happens in the desktop and window managers. Is there package managers for OSX like Synaptic or Adept? Is anybody at Apple smart enough to thwart low-level exploits, or do they only hire "trend-settings hipsters" to be developers? You obviously don't know much about OSes, maybe you should try to educate yourself before acting defiant to me.
  • Anonymous
    @rorosdad: So let me see if I understand your logic correctly:

    UNIX is an OS standard developed in the 70s

    Linux and OSX are both based on UNIX, therefore:

    Both must have equally good security, and:

    It doesn't matter how much OSX's developers suck, because if they screwed anything up, it wouldn't be UNIX anymore, because UNIX is perfect and unhackable.

    If I'm not mistaken, isn't Charlie Miller(subject of this interview) a hacker famous for pwning OSX? Do any of his exploits ever work on Linux? Hasn't he been quoted as saying that Linux and Windows are both much harder to hack than OSX? Isn't Apple's uber-shi.t Safari browser a liability in itself?
  • matt87_50
    "Charlie: I found the bug by sending in thousands of malformed SMS messages to the device, a process known as fuzzing."

    Apple's QA should have done this, this is similar to a Soak test, QA's bread and butter.

    oh and i'm sorry, what? "I can't fault them too much, it was hard to find". yes it would be hard to find, but to call it in the first place and not check the return type? to code it in such a way that it will only work if there is no error in the SMS (expected size == actual size).

    If i was worried about security at all, I would NOT buy a device coded like this. trusting a hardware buffer overrun protection system to handle all your problems? just pathetic!

    Good to see him call BS on the apple jailbreak argument!
    while I bet apple was all too happy to take his advice on how to patch the iphone, they will just ignore him on this point.
  • Anonymous
    @Synonymous Dude

    "...but Linux has done by far the best job of idiot-proofing an OS..."

    Yes, typing "tar zxvf blahblahblah-1.1-x86.gz cd /usr/bin/blah" is so "idiot-proof" that everyone will be doing it.
  • Anonymous
    vitalDude: Last time I checked, most distros come with a WinRAR-esque utility where you can double-click, extract, etc... Just like you would in Windows, although if you're talking about installing stuff with GNU Make, I doubt most Linux noobs would be installing stuff outside of package managers.

    Epic fail.
  • sdbryan
    rorosdads_dadrorosdad: ... Is anybody at Apple smart enough to thwart low-level exploits, or do they only hire "trend-settings hipsters" to be developers? ...

    It seems that you have never been to a Mac developer conference. I only bother to make that observation because the comment about "trend-setting hipsters" in reference to Apple's Mac OS team is so comical. It might be true about marketing people at Apple but it was easy to observe that as the api level got lower, the engineer from Apple got larger (wider rather than taller) and more disheveled. [Obviously being a trend-setting hipster was not a criterion for choosing personnel]. Any technology company that has been a significant player for well over thirty years is going to have its ups and downs but it is absurd to dismiss its engineering bona fides.
  • Anonymous
    sdbryan: Apples engineers are so good that they failed at writing their own OS, so they stole BSD because it was literally the only thing they could steal and then make closed-source. As a byproduct of this, they don't even have expertise of their own OS. The Windows API is pretty slick since .NET came out, but since not even Apple properly understands the inner-workings of OSX, they have buggy APIs, which is why nobody can properly port an application to OSX, anything that is cross-platform runs 1000x better on Windows, and much faster.
  • Anonymous
    @Ive_seen_the_promised_land: WRONG! OSX originated from NextOS which was an operation system developed by Steve Jobbs's break-away company called NextStep. The monolithic/micro kernel hybrid and base libraries come from a merged NextOS and BSD. The BSD libraries in use were not stolen and still remain open source. Apple help to maintain these libraries. The rest of the operating system including the UI is based on NextOS. NextStep merged with Apple. Many of the designs by NextStep became the modern day Apple designs. The Windows API is not slick - just look at the object model... hideous. No one ports windows applications to OSX because .NET "point and click" programmers can't program in an environment that is not "Visual" nor can they comprehend Java, Objective C or any other slightly intellectually challenging language like Ruby or Scala that allow you to program in a non-imperative way. Recursion? What's that?
  • Anonymous
    bottoms: If I understand you correctly, you're saying that Visual Studio makes programming entirely too easy? Of course, that kind of pointless elitism is consistent with Macs and their users. I'm a MS-hating Linux fanboy, but I can admit that Visual Studio raised the bar for IDEs, it is hard to use something lesser after you've used VS. Thankfully, there is Monodevelop, so I can still write C#/.NET apps in Linux without having to resort to more archaic IDEs that require ninja-like concentration skills for the entire coding session.