Jonathan Mayer is an Assistant Professor of Computer Science and Public Affairs at Princeton University. Before joining the Princeton faculty, Jonathan served as the technology law and policy advisor to United States Senator Kamala Harris and as the Chief Technologist of the Federal Communications Commission Enforcement Bureau. Jonathan's research centers on the intersection of technology and law, with emphasis on national security, criminal procedure, consumer privacy, network management, and online speech. Jonathan is both a computer scientist and a lawyer, and he holds a Ph.D. in computer science from Stanford University and a J.D. from Stanford Law School.
Click the local Home Depot ad and your email address gets handed to a dozen companies monitoring you. Your web browsing, past, present, and future, is now associated with your identity. Swap photos with friends on Photobucket and clue a couple dozen more into your username. Keep tabs on your favorite teams with Bleacher Report and you pass your full name to a dozen again. This isn't a 1984-esque scaremongering hypothetical. This is what's happening today.
[Update 10/11: Since several readers have asked – this study was funded exclusively by Stanford University and research grants to the Stanford Security Lab. It was not supported by any advocacy organization.]
A number of technologies have been touted to offer consumers control over third-party web tracking. This post reviews the tools that are available and presents empirical evidence on their effectiveness. Here are the key takeaways:
- Most desktop browsers currently do not support effective self-help tools. Mobile users are almost completely out of luck.
- Self-help tools vary substantially in performance.
- The most effective self-help tools block third-party advertising.
Following the usage model in the FTC staff's 2010 preliminary online privacy report, this post is oriented towards the user who wants a simple, persistent, comprehensive solution such that with high confidence no third party collects her browsing history. We assume that some third-party trackers will use non-cookie tracking methods including supercookies and fingerprinting (e.g. Microsoft, KISSmetrics, Epic Marketplace, BlueCava, Interclick, Quantcast).
Despite all the attention they've received in the debates around online privacy, cookies are far from the only way to track a user. Broadly speaking, a website can either stash a unique identifier anyplace in the browser ("tagging")1 or explore features of the browser until it becomes unique ("fingerprinting").2 Tracking technologies that do not rely on cookies are often referred to as "supercookies," and they are widely viewed as unsavory in the computer security community because they continue tracking even when a user clears her cookies to preserve privacy. Sometimes a site will use a supercookie to "respawn" its original identifier cookie, creating a "zombie cookie" — the basis of several lawsuits.
In one of our recent FourthParty web measurement crawls we included a cookie clearing step to emulate a user's privacy choice. We observed that after clearing the browser's cookies an identifier cookie (named "MUID" for "machine unique identifier") respawned on live.com, a Microsoft domain. We dug into Microsoft's cross-domain cookie syncing code and discovered two independent supercookie mechanisms, one of which was respawning cookies. We contacted Microsoft with our observations, and we have collaborated to assist in rectifying the issues we uncovered. Here is what we know.
Thanks, once again, to Jovanni Hernandez and Akshay Jagadeesh for their indispensable research assistance.
(Jovanni Hernandez and Akshay Jagadeesh are the first authors of this study.)
Last week marked the twentieth anniversary of the public World Wide Web, and there is much to celebrate. The early web consisted of a few text pages linked together; the modern web supports audio, video, interactivity, complex storage, and even native applications. Both Microsoft and Google are now developing entire operating systems around web technologies.
Today we're releasing FourthParty, an open-source platform for web measurement. FourthParty is built on Mozilla Firefox and the Add-on SDK, making it fast, modular, easy to use, multi-platform, and up-to-date with the latest web technologies. And FourthParty is already generating research results: it's the tool we've been using in our Tracking the Trackers studies (1, 2). To learn more and get started, visit fourthparty.info.
Thursday evening, the Attorney General, the Acting Homeland Security Secretary, and top law enforcement officials from the U.K. and Australia sent an open letter to Mark Zuckerberg. The letter emphasizes the scourge of child abuse content online, and the officials call on Facebook to press pause on end-to-end encryption for its messaging platforms.
Blocking cookies is bad for privacy. That’s the new disingenuous argument from Google, trying to justify why Chrome is so far behind Safari and Firefox in offering privacy protections. As researchers who have spent over a decade studying web tracking and online advertising, we want to set the record straight.
Our high-level points are:
1) Cookie blocking does not undermine web privacy. Google’s claim to the contrary is privacy gaslighting.
By Jonathan Mayer and Edward W. Felten
Special to The Bee
By Edward Felten and Jonathan Mayer
Snooping on the Internet is tricky. The network is diffuse, global, and packed with potential targets. There’s no central system for identifying or locating individuals, so it’s hard to keep track of who is online and what they’re up to. What’s a spy agency to do?
CIS Student Fellow Jonathan Mayer was mentioned in the following Stanford Daily article by Sandy Huang. The article covered a report authored by Mayer on privacy leaks that occur on highly visited websites.
Privacy leaks occur on 185 of the Internet’s top visited websites, according to a recent study by Stanford Law School’s Center for Internet and Society (CIS). The report was authored by Jonathan Mayer, a graduate student in computer science and at the School of Law. The report was released last Tuesday at a conference in Washington, D.C. hosted by the National Press Club.
Jonathan Mayer outlined tracking of Internet users by third-party Web trackers, focusing on a Stanford University study on the various ways people are tracked unknowingly online. After his speech he answered questions from the audience.
This program was part of a forum on Internet privacy co-sponsored by the American Civil Liberties Union, the Center for Digital Democracy, Consumer Action, Consumer Federation of America, Consumers Union, Consumer Watchdog, Electronic Privacy Information Center, Privacy Rights Clearinghouse, U.S. PIRG, and World Privacy Forum.
Student fellow Jonathan Mayer is the featured guest on a Martketplace radio broadcast covering the Do Not Track List option now available to web users. Here is a description and link to the interview:
The idea of a Do Not Track list for web users has been kicked around for a while. After the relative success of the Do Not Call telemarketing list, it seems like an easy and practical way for people to choose not to be tracked around the Internet by online advertisers.
Privacy and Civil Liberties Oversight Board Chairman Adam Klein and Board Members Edward Felten and Jane Nitze have announced a May 31, 2019 public forum in Washington, DC to examine the USA FREEDOM Act and the government’s call detail records (CDR) program under that law. Several key provisions of the USA FREEDOM Act will sunset in December unless they are reauthorized by Congress.
Advanced technologies are revolutionizing how the government investigates, charges and prosecutes criminal cases—and defense attorneys must keep pace. Even small police departments can purchase powerful surveillance technologies, and internet companies collect vast troves of data on virtually everyone. This two-day CLE conference will discuss the government's use of technologically advanced investigative techniques in criminal cases, and the issues raised by those techniques under the Fourth Amendment and other federal law.
Cybersecurity and Privacy in the Internet Economy: Information Sharing, Data Security, and Intellectual Property
Because of Edward Snowden’s remarkable public service, we know that the National Security Agency, with the cooperation of some large firms, has amassed an unprecedented database of personal information. The ostensible goal in collecting that information is to protect national security. The effect, according to Reed Hundt, is to undermine democracy.
This talk presents an empirical assessment of the NSA’s legal restrictions, including research cited by President Obama’s intelligence review group. We find that present limits on bulk surveillance programs come up far short; authorities to intercept international Internet traffic and domestic telephone metadata place ordinary Americans at risk.
In this first episode, Mike and I explore how your simplest digital footprints – fragments of Google searches, Facebook likes, and innocuous tweets – can expose deeply intimate facts about you. Like whether your parents are divorced and whether you own a gun. In fact, these vanilla datasets that we all generate every time we use the Internet reveal surprising clues about our personalities and behavior. So how can that information be used, and who is collecting it? We talk to Michal Kosinski of Stanford’s Graduate School of Business, and Jonathan Mayer, a computer scientist and lawyer.
As consumers increasingly adopt encryption tools, government officials have warned of the “Going Dark” problem – the notion that widespread encryption will thwart legitimate government efforts to investigate crime and safeguard national security. To address this problem, law enforcement and intelligence community officials have suggested that companies include “backdoors” in their products to permit lawful government access to encrypted data. This proposal has been met with criticism from technologists and privacy advocates alike.
"WELNA: It could indeed. Hackers, by definition, are trying to break into other people's computer accounts and steal their information, so monitoring their activity means watching them poach on other people's Internet usage and private data. I talked with Jonathan Mayer, a computer security fellow at Stanford who's reviewed these latest Snowden documents. He says because of the way the surveillance law is written, the NSA can actually hang on to that hacked information.
CIS Affiliate Scholar David Levine interviews Jonathan Mayer, Stanford Ph.D. candidate in computer science, author of Terms of Abuse: An Empirical Assessment of the Federal Hacking Law, and How to Fix It.
Listen to the full piece at Marketplace.org.
"Now Neustar might lose the contract to Ericsson, which is based in Sweden. Neustar says this would be bad for national security, said Jonathan Mayer, a fellow at Stanford's Center for International Security and Cooperation.
“It certainly is a legitimate concern that the company that routes calls is in position to know a fair amount about law enforcement and intelligence investigations,” Mayer said."