Posts tagged ‘webprivacy’

Online price discrimination: Conspicuous by its absence

The mystery about online price discrimination is why so little of it seems to be happening.

Consumer advocates and journalists among others have been trying to find smoking gun evidence of price discrimination — the overt kind where different customers are charged different prices for identical products based on how much they are willing to pay. (By contrast, examples of covert or concealed price discrimination abound; see, for example, my 2011 article.) Back in 2000 Amazon tried a short-lived experiment where prices of DVDs for new and for regular users were different. But that remains essentially the only example.

This should be surprising. Tailoring prices to individuals is far more technically feasible online than offline, since shoppers are either identified or at least have loads of behavioral data associated with their pseudonymous cookies. The online advertising industry claims that this is highly effective for targeting ads; estimating consumers’ willingness to pay shouldn’t be much harder. Clearly, price discrimination has benefits to firms engaging in it by allowing them to capture more of the “consumer surplus.” (Whether or not it is beneficial to consumers is a more controversial question that I will defer to a future post.) In fact, based on technical feasibility and economic benefits, one might expect the practice to be pervasive.

The evidence (or lack thereof)

A study out of Spain last year took a comprehensive look at online merchants, by far the most thorough analysis of its kind. They created two “personas” with different browsing histories — one of which visited discount sites and the other visited sites for luxury products. Each persona then browsed 200 e-commerce sites as well as search engines to see if they were treated differently. Here’s what the authors found:

  • There is evidence for search discrimination or steering where the high- and low-income personas are shown ads for high-end and low-end products respectively. In my opinion, the line between this practice and plain old behavioral advertising is very, very slim. [1]
  • There is no evidence for price discrimination based on personas/browsing histories.
  • Three of the 200 retailers including Staples varied prices based on the user’s location, but necessarily not in a way that can’t be explained by costs of doing business.
  • Visitors coming from one particular deals site ( saw lower prices at various retailers. (Discounting and “deals” are very common forms of concealed price discrimination.)

A new investigation by the Wall Street Journal analyzes Staples in more detail. While the Spain study found geographic variation in prices, the WSJ study goes further and shows a strong correlation between lower prices and consumers’ ability to drive to competitors’ stores, which is an indicator of willingness to pay. I’m not 100% convinced that they’ve ruled out alternative hypotheses, but it does seem plausible that Staples’ behavior constitutes actual price discrimination, even though geography is a far cry from utilizing behavioral data about individuals.

Other findings in the WSJ piece are websites that offer discounts for mobile users and location-dependent pricing on Lowe’s and Home Depot’s websites but with little evidence of being based on anything but costs of doing business.

So there we have it. Both studies are very thorough, and I commend the authors, but I consider their results to be mostly negative — very few companies are varying prices at all and none are utilizing anywhere near the full extent of data available about users. Other price discrimination controversies include steering by Orbitz and a hastily-retracted announcement by Coca Cola for vending machines that would tailor prices to demand. Neither company charged or planned to charge different prices for the same product based on who the consumer was.

In short, despite all the hubbub, I find overt price discrimination conspicuous by its absence. In a follow-up post I will propose an explanation for the mystery and see what we can learn from it.

[1] This is an automatic consequence of collaborative recommendation that suggests products to users based on what similar users have clicked on/purchased in the past. It does not require that any explicit inference of the consumer’s level of affluence be made by the system. In other words, steering, bubbling etc. are inherent features of collaborative filtering algorithms which drive personalization, recommendation and information retrieval on the Internet. This fact greatly complicates attempts to define, detect or regulate unfair discrimination online.

Thanks to Aleecia McDonald for reviewing a draft.

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January 8, 2013 at 4:57 am 4 comments

Web Privacy Measurement: Genesis of a Community

Last week I participated in the Web Privacy Measurement conference at Berkeley. It was a unique event because the community is quite new and this was our very first gathering. The WSJ Data Transparency hackathon is closely related; the Berkeley conference can be thought of as an academic counterpart. So it was doubly fascinating for me — both for the content and because of my interest in the sociology of research communities.

A year ago I explained that there is an information asymmetry when it comes to online privacy, leading to a “market for lemons.” The asymmetry exists for two main reasons: one is that companies don’t disclose what data they collect about you and what they do with it; the second is that even if they do, end users don’t have the capacity to aggregate and process that information and make decisions on the basis of it.

The Web Privacy Measurement community essentially exists to mitigate this asymmetry. The primary goal is to ferret out what is happening to your data online, and a secondary one is making this information useful by pushing for change, building tools for opt-out and control, comparison of different players, etc. The size of the community is an indication of how big the problem has gotten.

Before anyone starts trotting out the old line, “see, the market can solve everything!”, let me point out that the event schedule demonstrates, if anything, the opposite. The majority of what is produced here is intended wholly or partly for the consumption of regulators. Like many others, I found the “What privacy measurement is useful for policymakers?” panel to be the most interesting one. And let’s not forget that most of this is Government-funded research to begin with.

This community is very different from the others that I’ve belonged to. The mix of backgrounds is extraordinary: researchers mainly from computing and law, and a small number from other disciplines. Most of the researchers are academics, but a few work for industrial research labs, a couple are independent, and one or two work in Government. There were also people from companies that make privacy-focused products/services, lawyers, hobbyists, scholars in the humanities, and ad-industry representatives. Overall, the community has a moderately adversarial relationship with industry, naturally, and a positive relationship with the press, regulators and privacy advocates.

The make-up is somewhat similar to the (looser-knit) group of researchers and developers building decentralized architectures for personal data, a direction that my coauthors and I have taken a skeptical view of in this recent paper. In both cases, the raison d’être of the community is to correct the imbalance of power between corporations and the public. There is even some overlap between the two groups of people.

The big difference is that the decentralization community, typified by Diaspora, mostly tries to mount a direct challenge and overthrow the existing order, whereas our community is content to poke, measure, and expose, and hand over our findings to regulators and other interested parties. So our potential upside is lower — we’re not trying to put a stop to online tracking, for example — but the chance that we’ll succeed in our goals is much higher.

Exciting times. I’m curious to see how things evolve. But this week I’m headed to PLSC, which remains my favorite privacy-related conference.

Thanks to Aleecia McDonald for reviewing a draft.

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June 4, 2012 at 8:47 am Leave a comment

One Click Frauds and Identity Leakage: Two Trends on a Collision Course

One of my favorite computer security papers of 2010 is by Nicolas Christin, Sally Yanagihara and Keisuke Kamataki on “one click frauds,” a simple yet shockingly effective form of social engineering endemic to Japan. I will let the authors explain:

In the family apartment in Tokyo, Ken is sitting at his computer, casually browsing the free section of a mildly erotic website. Suddenly, a window pops up, telling him,

Thank you for your patronage! You successfully registered for our premium online services, at an incredible price of 50,000 JPY. Please promptly send your payment by bank transfer to ABC Ltd at Ginko Bank, Account 1234567. Questions? Please contact us at 080-1234-1234.

Your IP address is, you run Firefox 3.5 over Windows XP, and you are connecting from Tokyo.

Failure to send your payment promptly will force us to mail you a postcard reminder to your home address. Customers refusing to pay will be prosecuted to the fullest extent of the law. Once again, thank you for your patronage!

A sample postcard reminder is shown on the screen, and consists of a scantily clad woman in a provocative pose. Ken has a sudden panic attack: He is married, and, if his wife were to find out about his browsing habits, his marriage would be in trouble, possibly ending in divorce, and public shame. In his frenzied state of mind, Ken also fears that, if anybody at his company heard about this, he could possibly lose his job. Obviously, those website operators know who he is and where he lives, and could make his life very difficult. Now, 50,000 JPY (USD 500) seems like a small price to pay to make all of this go away. Ken immediately jots down the contact information, goes to the nearest bank, and acquits himself of his supposed debt.

Ken has just been the victim of a relatively common online scam perpetrated in Japan, called “One Click Fraud.” In this fraud, the “customer,” i.e., the victim, does not enter any legally binding agreement, and the perpetrators only have marginal information about the client that connected to their website (IP address, User-Agent string), which does not reveal much about the user. However, facing a display of authority stressed by the language used, including the notion that they are monitored, and a sense of shame from browsing sites with questionable contents, most victims do not realize they are part of an extortion scam. Some victims even call up the phone numbers provided, and, in hopes of resolving the situation, disclose private information, such as name or address, to their tormentors, which makes them even more vulnerable to blackmail.

As a result, One Click Frauds have been very successful in Japan. Annual police reports show that the estimated amount of monetary damages stemming from One Click Frauds and related confidence scams are roughly 26 billion JPY per year (i.e., USD 260 million/year). [emphasis mine]

The authors offer a fascinating economic analysis based on a near-exhaustive collection of fraud reports over a several-year period. Each scam offers 3 types of data points: the domain name where the scam appeared, the phone number the victim is asked to call, and the bank account number where the money is asked to be deposited. They plot the graph of all links between the ~500 domains, ~700 bank accounts and ~200 phone numbers, and report, among other nifty findings, that at most 13 groups are responsible for over half of all one-click frauds. Based on simple cost estimates, they also find that for each scam operated, the scammers recover their costs (bank account fee, bandwidth, etc.) with as few as 4 victims per year.

In this post I want to talk about the possible evolution of one-click frauds. At some point, either due to public awareness campaigns or due to saturation, the Japanese public will catch on to the fact that the attempted blackmail is fake and that the websites don’t actually have their identity. When this happens the scammers will be forced to up their game. Another impetus for increasing sophistication is making the fraud work outside Japan—the current version probably won’t work; the instinctive obedience of apparent authority seems characteristically Japanese.

And by ‘up their game,’ I mean that the scammers will probably get wise to the fact that they can discover the victim’s actual identity, and establish a credible threat instead of a fake one.

Readers of this blog know that I have announced or reported numerous attacks/vulnerabilities under the “ubercookies” series (1, 2, 3, 4, and part of 5) that allow a website to uncover a visitor’s identity, i.e., a Google/Facebook/Twitter handle. At the same time, connecting an online profile or email address to real-world information is becoming increasingly easy to automate. Putting two and two together, it is clear why one-click frauds could get very serious any day.

What might stop this logical progression of one-click frauds? Perhaps all identity-leak vulnerabilities will be found and fixed, but that’s a rather naïve hope, as the history of malware shows. Or maybe the public will eventually learn to resist the scam even in the face of a credible threat. That will take a long time, however, and a lot of damage will be done by then. Perhaps the technical skills required will remain beyond the reach of the scammers. But experience suggests that with a sufficiently lucrative prize, technical sophistication is no barrier—all it takes is one or two actual hackers; script-kiddie scammers can take care of the rest.

The best hope, as with any scam, is law enforcement. The authors list several factors, many specific to Japan, why the prosecution probability for one-click frauds is currently low. In addition, penalties for those who do get caught are also low: “One Click Frauds very often do not meet the legal tests necessary for qualifying as “fraud,” as in the vast majority of cases, the victim pays up immediately, and there is no active blackmailing effort from the miscreant.” A version of the scam that involved identity stealing would likely fall under the US Computer Fraud and Abuse Act or an equivalent, and would thus be more clearly illegal. Will this make a difference? Let’s wait and see.

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February 21, 2011 at 5:30 pm 2 comments


I’m an associate professor of computer science at Princeton. I research (and teach) information privacy and security, and moonlight in technology policy.

This is a blog about my research on breaking data anonymization, and more broadly about information privacy, law and policy.

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