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A collection of tips, tricks and snips. A proud Blosxom weblog. All code. No cruft.

Sat, 18 Feb 2017

The making of a Docker: Part II - Wickr: with bonus analysis

Recently, I read a rather excited attention-catching piece about how Wickr is the super-secure version of Slack. Attention caught in part because I feel like Wickr has been around for a while. I’d not seen anyone raving about its security in places where I normally interact with those who are highly informed about such subjects.

Good is that it seems the folk at Wickr did a fine job of making sure valuable data aren’t left behind.
The bad: closed-source, not subject to independent review; crazy marketin’-fancy-talk without a thorough description of how it does what is claimed.
Any time I’m looking at a product or service that boasts security, I sort of expect to see a threat model.

[ Update: At the time I was working on this project, the folk at Wickr were, evidently, opening their source. That’s spectacular news! Check it out on Github. ]

This began as an exercise to provide another piece of security-ish software in a Docker container. Anyone who has used a live distro (e.g., Kali, TAILS) with any regularity knows the ritual of installing favorite tools at each boot, data stores on removable media.

For me, there is tremendous appeal in reducing that to something like:
git clone https://georgeglarson/wickr
cd docker-wickr
./install.sh
wickr

Let’s dig in!

Having created a number of Docker containers my workflow is to queue up the base OS and go through the steps needed to get the software running while keeping careful notes. In this case, I had originally tried to install Wickr on a current copy of Kali. It was already known that Wickr, based off of Ubuntu 14.04, needed an older unicode library. So we begin with Ubuntu 14.04.

Grab a copy of Wickr and see what’s required:
dpkg -I wickr-me_2.6.0_amd64.deb

new debian package, version 2.0.
size 78890218 bytes: control archive=4813 bytes.
558 bytes, 14 lines control
558 bytes, 14 lines control64
10808 bytes, 140 lines md5sums
Package: wickr-me
Architecture: amd64
Section: net
Priority: optional
Version: 2.6.0-4
Replaces: wickr
Conflicts: wickr
Depends: libsqlcipher0, libuuid1, libicu52, libavutil52|libavutil54, libc6, libssl1.0.0, libx264-142, libglib2.0-0, libpulse0, libxrender1, libgl1-mesa-glx
Recommends: libnotify-bin, gstreamer-plugins0.10-good, gstreamer-plugins0.10-bad, gstreamer-plugins0.10-ugly
Maintainer: Wickr Inc.
Installed-Size: 200000
Description: Secure Internet Chat and Media Exchange agent
Wickr is a secure communications client

Okay. The CLI should do most of the work for us, giving a formatted list of dependencies.
dpkg -I wickr-me_2.6.0_amd64.deb | grep -E "^ Depends: | Recommends: " | sed -e "s/ Depends: //" -e "s/ Recommends: //" -e "s/,//g" -e "s/ / \\\ \n/g"

libsqlcipher0 \
libuuid1 \
libicu52 \
libavutil54 \
libc6 \
libssl1.0.0 \
libx264-142 \
libglib2.0-0 \
libpulse0 \
libxrender1 \
libgl1-mesa-glx
libnotify-bin \
gstreamer-plugins0.10-good \
gstreamer-plugins0.10-bad \
gstreamer-plugins0.10-ugly \

Attempting to get those with apt-get reports that it cannot find the gstreamer bits.

Let’s find:
apt-cache search gstreamer | grep -i plugin | grep -E "good|bad|ugly"

gstreamer0.10-plugins-good - GStreamer plugins from the "good" set
...
gstreamer0.10-plugins-bad - GStreamer plugins from the "bad" set
...
gstreamer0.10-plugins-ugly - GStreamer plugins from the "ugly" set

So, there’s the format we need to get the gstreamer dependencies. We know that we’ll also want SSH and wget. That should be enough for our Dockerfile.

We’ll pull down Wickr:
wget https://dls.wickr.com/Downloads/wickr-me_2.6.0_amd64.deb

Then install:
dpkg -i wickr-me_2.6.0_amd64.deb

Okay! We are, in theory, ready to run Wickr. We’re about to see we aren’t yet there — but these sorts of problems are pretty commonplace.
wickr-me

wickr-me: error while loading shared libraries: libxslt.so.1: cannot open shared object file: No such file or directory

Huh! We need libxslt. Let’s fix that: apt-get install libxslt1-dev

Now we can run it.
wickr-me

This application failed to start because it could not find or load the Qt platform plugin "xcb".

Available platform plugins are: eglfs, linuxfb, minimal, minimalegl, offscreen, xcb.

Reinstalling the application may fix this problem.
Aborted (core dumped)

One more: apt-get install xcb

Okay. That really was the last one. Now we have a complete list of dependencies for our Dockerfile:
RUN apt-get update && apt-get install -y \
gstreamer0.10-plugins-good \
gstreamer0.10-plugins-bad \
gstreamer0.10-plugins-ugly \
libsqlcipher0 \
libuuid1 \
libicu52 \
libavutil52 \
libc6 \
libssl1.0.0 \
libx264-142 \
libglib2.0-0 \
libpulse0 \
libxrender1 \
libxslt1-dev \
libgl1-mesa-glx \
libnotify-bin \
ssh \
wget \
xcb \
&& apt-get clean \

We now have Wickr in a Docker container and, because we are the curious sort, need to peek into what’s happening.

A natural first step is to set Wireshark atop Wickr. At a glance, seems to be communicating with a single IP address (204.232.166.114) via HTTPS.

Unsurprsingly, the client communicates to the server whenever a message is sent. Further it appears to poll the same address periodically asking for new messages. We see that the address resolves to Rackspace in San Antonio, TX.

We can easily establish the link between this IP address, Rackspace and the application.

Well, that’s enough. Right?

Good!

Wait.

What?

We’re still a little curious.

Aren’t we?

I mean, what’s the big question here? What happens if there’s a man in the middle? Persons so eagerly connect to any free WIFI, it is clearly a plausible scenario. Well… One way to find out!

Here’s what we learned. Server-side, the application is written in PHP. The IP address is resolved by the URI ‘secex.info’.

When we send, it calls ‘postMessage.php’:

When we receive, ‘downloadMessage.php’:

And it calls ‘newMessageCheck.php’ to, y’know, check for new messages.

Other analyses have forensically examined artefacts left behind; there are published descriptions of the encryption methods used for the local database connection. We didn’t go into more aggressive efforts such as disassembly because we are too lazy for that jazz!

My opinion, we didn’t learn anything wildly unexpected. Overall, Wickr seems an okay solution for convenient encrypted messaging. That’s always the trade: convenience vs. security. Least we ended with a Docker container for the software!

Github | Docker


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