This is great stuff. One of the things that would be interesting future work is how safe are the protocols to use over tor in terms of cleartext exposure to exit nodes. I thought all of the google apps on the phone were using SSL, and it surprises greatly me to learn that the app market uses cleartext in any way.
Is that all market activity, or just some API calls? Can exit nodes
(or open wifi access points) give you altered apps, for example? Or simply delay critical updates by breaking connections because they can see you are trying to update from a vulnerable version of a particular app? This seems like a huge nightmare...
Thus spake Nathan Freitas (nathan@xxxxxxxxxxx):
> Fantastic, Manuel. Looks like we are going to need some wine over to
> patch this up. This type of look at how our transproxy all rules are
> working (or not) is long overdue. I really appreciate your effort.
>
> The first thing that comes to mind is that we are setting up the
> iptables rules on an app-by-app basis, using the list of user IDs we are
> provided by Android API calls. It is quite possible that certain
> subsystems are not represented in that list.
>
> There may be a better way to implement the transproxy all implementation
> that is more of a "everything but tor" approach.
>
> Our transproxy configuration is based on the approach outlined here:
>
https://trac.torproject.org/projects/tor/wiki/TheOnionRouter/TransparentProxy
>
> We'll have to go through additional recommended configurations that we
> are not addressing in our current "all" setup, and see if they address
> the leakage you have found.
>
> Best,
> Nathan
>
> On 04/27/2011 12:40 PM, Manuel wrote:
> > Hi all!
> >
> > Mini-intro: Hi, I'm Manuel (aka __sporkbomb), infosec researcher from
> > Austria, got bored and asked Nathan if he wanted help with ORBot ;)
> >
> > Setup: Simply an open AP, a Desire HD running CM 7.0.2 and
> > 0.2.2.22-orbot-alpha-1.0.5.20110417a-dev plus airodump.
> >
> > Methodology: The dump was started after the tor connection (and full
> > transproxying) was established in order to reduce false positives. Total
> > dump length is around 3h15m, around 57MB of data. Of course the phone
> > was left idle for a quite a while, also to ensure that it didn't do
> > nasty untorified stuff when waking up to check mails. Afterwards, I used
> > Wireshark's 'Endpoints' statistics function to determine all TCP
> > endpoints in the dump[0] and awk'd & uniq'd the IPs out of it[1]. As the
> > next step, I determined which of these IPs was in my cached-consensus[2]
> > (somewhat ill-advised, because I compared with my laptop's
> > cached-consensus rather than the phone's, causing two false positives
> > [false non-tor nodes] that actually were nodes). I also ran a reverse
> > lookup on all IPs [3]. As the last step, I went through all
> > communication with IPs that were not found in cached-consensus[4].
> >
> > You can find links to most of the files I produced at the end of this
> > mail, excluding the dump, which I can provide if requested, but would
> > rather not hand out publicly (mostly because of the size).
> >
> > All in all, the phone connected to 88 IPs during that time. 37 of those
> > were not contained in the laptop's cached-consensus, two of which were
> > actually legitimate nodes (according to
metrics.torproject.org) that
> > just went down throughout the duration of the test, leaving us with 35
> > non-Tor IPs. They can be categorized as follows:
> >
> > - 27 of those nodes had no other communication than multiple TCP
> > packets, sometimes from a few different source ports (i.e. different TCP
> > connections), all originating from the phone and having FIN+PSH+ACK set.
> > (PSH is the 'push flag', which requests that this data bypass buffers
> > and be handed directly to the application)
> >
> > - 4 existing connections that still transmitted data; one even contained
> > Market HTTP (cleartext) API requests.
> >
> > - 4 were completely unencrypted and newly established connections to
> > YouTube or Revision3 video servers. This one is rather bad - it seems
> > that the video player subsystem of Android ignores the proxy setting and
> > leaks everything, including DNS. I also mentioned this yesterday on
> > Twitter, but didn't want to post it yet without confirmation, but it's
> > definitely reproducible on my end.
> >
> > --------------------
> > Sumup of this part: Generally solid performance, but already established
> > connections might pose a threat (a minor one I'd guess, however...unless
> > one of you can think of a scenario where that causes Bad Things to
> > happen?). Additionally, the video player completely ignores the proxy
> > setting and communicates untorified. While video streaming isn't a
> > strong point of Tor anyway, it's still not good...does anyone have good
> > contact to CyanogenMod people and can ask about that one?
> >
> > Various tidbits of slight UX annoyances plus a few suggestions:
> > - ORBot ignores the "Transparent proxy" setting when connecting, I
> > always have to enter the Settings menu, untick and re-tick "Transparent
> > proxying" and press back to actually cause it to be enabled.
> > - Related to this: Is it possible to colour-code the "Transparent
> > proxying {DIS,EN}ABLED" notification? The bug above might have serious
> > consequences, because if someone doesn't visit
check.torproject.org to
> > assure that he/she is actually torified, chances are that he/she will
> > browse in clear. DISABLED and ENABLED are only three characters away
> > from each other, whereas a red vs green notification would probably
> > catch the eye.
> > - Install fails when installing/uncompressing tor binary
> >
https://trac.torproject.org/projects/tor/ticket/2989 [turns out that
> > this is only a bug on Android<2.3, but still...see comment #1 for more
> > details]
> > - Blank semi-permanent status box
> >
https://trac.torproject.org/projects/tor/ticket/2993 [haven't updated
> > this one yet; the bug actually occured only before the first reboot for
> > me, and one time afterwards when I had b0rked the network badly]
> > - ORBot vs DroidWall: Starts with 'You don't preserve my chains like you
> > used to :(' and ends with, if I remember correctly, ORBot flushing
> > iptables rules. I'll have a look at that one tomorrow (or is there
> > already some data on it?).
> >
> > For now, have a nice evening!
> >
> > Cheers,
> >
> > __sporkbomb
> >
> >
> >
> >
> >
> > [0]
http://sporkbomb.eu/orbot/endpoints
> > [1]
http://sporkbomb.eu/orbot/ips
> > [2]
http://sporkbomb.eu/orbot/inconsensus (result of a grep -c - IPs
> > with '0' in the second field are not contained in the consensus)
> > [3]
http://sporkbomb.eu/orbot/dig-result
> > [4]
http://sporkbomb.eu/orbot/not-inconsensus.notes
> >
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