OpenWPM

OpenWPM is a web privacy measurement framework which makes it easy to collect data for privacy studies on a scale of thousands to millions of site. OpenWPM is built on top of Firefox, with automation provided by Selenium. It includes several hooks for data collection, including a proxy, a Firefox extension, and access to Flash cookies. Check out the instrumentation section below for more details.

Installation

OpenWPM has been developed and tested on Ubuntu 14.04/16.04. An installation script, install.sh is included to install both the system and python dependencies automatically. A few of the python dependencies require specific versions, so you should install the dependencies in a virtual environment if you're installing a shared machine. If you plan to develop OpenWPM's instrumentation extension or run tests you will also need to install the development dependencies included in install-dev.sh.

It is likely that OpenWPM will also work on Mac OSX, however this has not been tested. If you have experience running OpenWPM on other platforms, please let us know!

Quick Start

Once installed, it is very easy to run a quick test of OpenWPM. Check out demo.py for an example. This will the default setting specified in automation/default_manager_params.json and automation/default_browser_params.json, with the exception of the changes specified in demo.py.

You can test other configurations by changing the values in these two dictionaries. manager_params is meant to specify the platform-wide settings, while browser_params specifies browser-specific settings (and as such defaults to a list of settings, of length equal to the number of browsers you are using. A description of the instrumentation available is included below.

The wiki provides a more in-depth tutorial, however portions of it are currently outdated. In particular you can find advanced features, and additional commands. You can also take a look at two of our past studies, which use the infrastructure:

1. The Web Never Forgets
2. Cookies that Give You Away

Instrumentation and Data Access

OpenWPM provides several instrumentation modules which can be enabled independently of each other for each crawl. With the exception of Javascript response body content, all instrumentation saves to a SQLite database specified by manager_params['database_name'] in the main output directory. Javascript bodies are saved to javascript.ldb. The SQLite schema specified by: automation/schema.sql, instrumentation may specify additional tables necessary for their measurement data (see extension tables).

• HTTP Request and Response Headers
  • Set browser_params['http_instrument'] = True
  • Data is saved to the http_requests and http_responses tables.
  • Note: request and response headers for cached content are also saved, with the exception of images. See: Bug 634073.
• Javascript Calls
  • Records all method calls (with arguments) and property accesses for APIs of potential fingerprinting interest:
    • HTML5 Canvas
    • HTML5 WebRTC
    • HTML5 Audio
    • Plugin access (via navigator.plugins)
    • MIMEType access (via navigator.mimeTypes)
    • window.Storage, window.localStorage, window.sessionStorage, and window.name access.
    • Navigator properties (e.g. appCodeName, oscpu, userAgent, ...)
    • Window properties (via window.screen)
  • Set browser_params['js_instrument'] = True
  • Data is saved to the javascript table.
• Javascript Files
  • Saves all Javascript files encountered during the crawl to a LevelDB database de-duplicated by the md5 hash of the content.
  • Set browser_params['save_javascript'] = True
  • The content_hash column of the http_responses table contains the md5 hash for each script, and can be used to do content lookups in the LevelDB content database.
  • This instrumentation can be easily expanded to other content types.
• Flash Cookies
  • Recorded by scanning the respective Flash directories after each page visit.
  • To enable: call the CommandSequence::dump_flash_cookies command after a page visit. Note that calling this command will close the current tab before recording the cookie changes.
  • Data is saved to the flash_cookies table.
  • NOTE: Flash cookies are shared across browsers, so this instrumentation will not correctly attribute flash cookie changes if more than 1 browser is running on the machine.
• Cookie Access (Experimental -- Needs tests)
  • Set browser_params['cookie_instrument'] = True
  • Data is saved to the javascript_cookies table.
  • Will record cookies set both by Javascript and via HTTP Responses
• Content Policy Calls (Experimental -- Needs tests)
  • Set browser_params['cp_instrument'] = True
  • Data is saved to the content_policy table.
  • Provides additional information about what caused a request and what it's for
  • NOTE: This instrumentation is largely unchanged since it was ported from FourthParty, and is not linked to any other instrumentation tables.
• Cookie Access (Alternate)
  • Recorded by scanning the cookies.sqlite database in the Firefox profile directory.
  • Should contain both cookies added by Javascript and by HTTP Responses
  • To enable: call the CommandSequence::dump_profile_cookies command after a page visit. Note that calling this command will close the current tab before recording the cookie changes.
  • Data is saved to the profile_cookies table
• Log Files
  • Stored in the directory specified by manager_params['data_directory'].
  • Name specified by manager_params['log_file'].
• Browser Profile
  • Contains cookies, Flash objects, and so on that are dumped after a crawl is finished
  • Automatically saved when the platform closes or crashes by specifying browser_params['profile_archive_dir'].
  • Save on-demand with the CommandSequence::dump_profile command.
• DEPRECATED HTTP Request and Response Headers via mitmproxy
  • This will be removed in future releases
  • Set browser_params['proxy'] = True
  • Data is saved to the http_requests_proxy and http_responses_proxy tables.
  • Saves both HTTP and HTTPS request and response headers
  • Several drawbacks:
    • Cached requests and responses are missed entirely (See #71)
    • Some HTTPS connections fail with certificate warnings (See #53)
    • The mitmproxy version used (v0.13) is a few releases behind the current mitmproxy library and will likely continue to have more issues unless updated.
    • Has significantly less context available around a request/response than is available from within the browser.
• DEPRECATED Javascript Response Bodies via mitmproxy
  • This will be removed in future releases
  • Set browser_params['save_javascript_proxy'] = True
  • Saves javascript response bodies to a LevelDB database de-duplicated by the murmurhash3 of the content. content_hash in http_response_proxy keys into this content database.
  • NOTE: In addition to the other drawbacks of proxy-based measurements, content must be decoded before saving and not all current encodings are supported. In particular, brotli (br) is not supported.
• DEPRECATED HTTP Request and Response Cookies via mitmproxy
  • This will be removed in future releases
  • Derived post-crawl from proxy-based HTTP instrumentation
  • To enable: call python automation/utilities/build_cookie_table.py <sqlite_database>.
  • Data is saved to the http_request_cookies_proxy and http_response_cookies_proxy tables.
  • Several drawbacks:
    • Will not detect cookies set via Javascript, but will still record when those cookies are sent with requests.
    • Cookie parsing is done using a custom Cookie.py module. Although a significant effort went into replicating Firefox's cookie parsing, it may not be a faithful reproduction.

Disclaimer

Note that OpenWPM is under active development, and should be considered experimental software. The repository may contain experimental features that aren't fully tested. We recommend using a tagged release.

Although OpenWPM is actively used by our group for research studies and we regularly use of the data collected, it is still possible there are unknown bugs in the infrastructure. We are in the process of writing comprehensive tests to verify the integrity of all included instrumentation. Prior to using OpenWPM for your own research we encourage you to write tests (and submit pull requests!) for any instrumentation that isn't currently included in our test scripts.

Citation

If you use OpenWPM in your research, please cite our CCS 2016 publication on the infrastructure. You can use the following BibTeX.

@inproceedings{englehardt2016census,
    author    = "Steven Englehardt and Arvind Narayanan",
    title     = "{Online tracking: A 1-million-site measurement and analysis}",
    booktitle = {Proceedings of ACM CCS 2016},
    year      = "2016",
}

License

OpenWPM is licensed under GNU GPLv3. Additional code has been included from FourthParty and Privacy Badger, both of which are licensed GPLv3+.