TLS Client Certificate Authentication and its Privacy Implications
Switch branches/tags
Nothing to show
Clone or download
Fetching latest commit…
Cannot retrieve the latest commit at this time.

README.md

Push Away Your Privacy: Precise User Tracking Based on TLS Client Certificate Authentication

This repository contains additional information, measurement data, and tools for the paper Push Away Your Privacy: Precise User Tracking Based on TLS Client Certificate Authentication published at TMA 2017.

If you have any questions, please do not refrain from contacting one of the authors:

  • Matthias Wachs [lastname] @ net.in.tum.de
  • Quiring Scheitle [lastname] @ net.in.tum.de PGP Key
  • Georg Carle [lastname] @ net.in.tum.de

If you want to reproduce our work, you might find the TMA'17 PhD School Lab helpful, which reproduces parts of this paper.

Please use OpenPGP to protect the communication!

Capturing TLS client certificate authentication traffic

To analyze TLS client certificate authentication, we used tcpdump command to capture TLS Client Certificate packets on APNs ports 443, 5223, 2195 and 2196:

tcpdump -n -i eth6 -s 0 'tcp[((tcp[12:1] & 0xf0) >> 2)+5:1] = 0x0b and tcp[((tcp[12:1] & 0xf0) >> 2):1] = 0x16 and ( tcp dst port 443 or tcp dst port 5223 or tcp dst port 2195 or tcp dst port 2196)' -G 3600 -w tls-cca-%Y%m%d-%H%M.pcap

Captured TLS Handshakes

APNs handshakes

For further analysis, we provide captures APNs of handshakes for iOS, macOS, and iTunes on Windows before and after the fix provided by Apple. We have rewritten MAC and IP addresses for privacy in a documented process. Please contact us should you require non-rewritten copies.

iOS 10.2

iOS 10.2 (vulnerable) -- iOS 10.2.1-beta4 (fixed)

macOS 10.12.x

macOS 10.12.2 (vulnerable) -- macOS 10.12.3-beta4 (fixed)

iTunes 12.5.4.42

iTunes 12.5.4.42 on Windows 10 (vulnerable)

More files and versions are available in the same directory.

FCM and WNS handshakes

In addition to Apple's APNs, we analyzed authentication traffic of Google's FCM and Microsoft's WNS push notification services for certificate based client authentication.

Google FCM

Google's FCM uses port TLS over TCP ports 5228 to 5230: Google FCM Handshake PCAP

Microsoft WNS

Microsoft's WNS uses TLS over TCP port 443: Microsoft WNS Handshake

Parsing tcpdump network dumps

Our first step is to parse the captured .pcap files into a database. This and further steps are described under parser.

Certificate Analyses

We analyze the outputs from the queries above using Jupyter Notebook. Its input data and the notebook files are accessible under analyses. Please note that we have anonymized data where adviseable, and provide the scripts we used to do so.

User Study

The (anonymized) raw data and scripts for our tracking user study can be found under userstudy

RIPE Atlas Measurements

The folder ripe_atlas contains subdirectories dns and traceroute.

DNS

The dns subdirectory contains the scripts used to resolve APNs DNS names through Ripe Atlas and extract one random target IP address per observed /24 subnet. Details are listed unter dns/dns.md.
The resulting artifacts are also stored in the ripe-atlas-dns-responses.tar.bz2 file in the dns subdirectory.

Traceroute

In the traceroute subdirectory, you will find scripts to generate global and german measurements, alongside with the target list, the resulting measurement IDs, and the resulting artifacts.