1. Privacy Policy, Law and Technology Online Privacy
September 30, 2008

2. Evaluating information sources
Don’t believe everything you read!
News sources are usually a reporter's interpretation of what someone else did
Conference and journal papers are first hand reports of research studies that have been peer reviewed
but journals usually have more review than conferences
Technical reports are usually first hand reports of research studies that have not been peer reviewed (yet)
Look for subsequent conference or journal publications
Web sites and books are anything goes, but books at least have an editor (usually)
When possible, cite research results and technical information from peer reviewed sources

3. How are online privacy concerns different from offline privacy concerns?

4. Web privacy concerns Data is often collected silently
Web allows large quantities of data to be collected inexpensively and unobtrusively
Data from multiple sources may be merged
Non-identifiable information can become identifiable when merged
Data collected for business purposes may be used in civil and criminal proceedings
Users given no meaningful choice
Few sites offer alternatives

5. Unsolicited marketing
Desire to avoid unwanted marketing (spam, postal mail, telemarketing) causes some people to avoid giving out personal information
May not seem very important from a privacy perspective, but this is actually one of the biggest concerns that people talk about
The computer will track what I do and then I’ll get lots of junk mail about it

6. My computer can “figure things out about me”
The little people inside my computer might know it’s me…
… and they might tell their friends

7. Inaccurate inferences
“My TiVo thinks I’m gay!”

8. Surprisingly accurate inferences
Everyone wants to be understood.
No one wants to be known.

9. You thought that on the Internet nobody knew you were a dog…
The problem is, you all thought that on the Internet nobody knew you were a dog…
…but then you started getting personalized ads for your favorite brand of dog food

10. Price discrimination Concerns about being charged higher prices
Concerns about being treated differently
Economists love price discrimination because in theory it leads to everyone being better off, but consumers hate it.
Any time there is a suggestion that an ecommerce retailer is engaging in price discrimination, people are outraged.

11. Revealing private information to other users of a computer
Revealing info to family members or co-workers
Gift recipient learns about gifts in advance
Co-workers learn about a medical condition
Revealing secrets that can unlock many accounts
Passwords, answers to secret questions, etc.

12. Exposing secrets to criminals
Stalkers, identity thieves, etc.
People who break into account may be able to access profile info
People may be able to probe recommender systems to learn profile information associated with other users

13. Subpoenas
Data on online activities is increasingly of interest in civil and criminal cases
The only way to avoid subpoenas is to not have data
In the US, your files on your computer in your home have much greater legal protection that your files stored on a server on the network

14. Government surveillance
Governments increasingly looking for personal records to mine in the name of fighting terrorism
People may be subject to investigation even if they have done nothing wrong

15. Citizen surveillance

16. Risks may be magnified in future
Wireless location tracking
Semantic web applications
Ubiquitous computing

17. How online tracking works

18. Browser Chatter Browsers chatter about
IP address, domain name, organization,
Referring page
Platform: O/S, browser
What information is requested
URLs and search terms
Cookies
To anyone who might be listening
End servers
System administrators
Internet Service Providers
Other third parties
Advertising networks
Anyone who might subpoena log files later

19. Typical HTTP request with cookie
GET /retail/searchresults.asp?qu=beer HTTP/1.0
Referer:
User-Agent: Mozilla/4.75 [en] (X11; U; NetBSD 1.5_ALPHA i386)
Host:
Accept: image/gif, image/jpeg, image/pjpeg, */*
Accept-Language: en
Cookie: buycountry=us; dcLocName=Basket; dcCatID=6773; dcLocID=6773; dcAd=buybasket; loc=; parentLocName=Basket; parentLoc=6773; ShopperManager%2F=ShopperManager%2F=66FUQULL0QBT8MMTVSC5MMNKBJFWDVH7; Store=107; Category=0

20. Referer log problems GET methods result in values in URL
These URLs are sent in the referer header to next host
Example:
Access log example:

21. Cookies What are cookies? What are people concerned about cookies?
What useful purposes do cookies serve?

22. Cookies 101 Cookies can be useful Cookies can do unexpected things
Used like a staple to attach multiple parts of a form together
Used to identify you when you return to a web site so you don’t have to remember a password
Used to help web sites understand how people use them
Cookies can do unexpected things
Used to profile users and track their activities, especially across web sites

23. How cookies work – the basics
A cookie stores a small string of characters
A web site asks your browser to “set” a cookie
Whenever you return to that site your browser sends the cookie back automatically
Please store cookie xyzzy
Here is cookie xyzzy
site
browser
site
browser
First visit to site
Later visits

24. How cookies work – advanced
Cookies are only sent back to the “site” that set them, but this may be any host in domain
Sites setting cookies indicate path, domain, and expiration for cookies
Cookies can store user info or a database key that is used to look up user info
Either way the cookie enables info to be linked to the current browsing session
Send me with any request to x.com until 2008
Send me with requests for index.html on y.x.com for this session only
Database Users … …
Visits …
User=Joe
= x.com
Visits=13
User=

25. Cookie terminology Cookie Replay – sending a cookie back to a site
Session cookie – cookie replayed only during current browsing session
Persistent cookie – cookie replayed until expiration date
First-party cookie – cookie associated with the site the user requested
Third-party cookie – cookie associated with an image, ad, frame, or other content from a site with a different domain name that is embedded in the site the user requested
Browser interprets third-party cookie based on domain name, even if both domains are owned by the same company

26. Web bugs
Invisible “images” (1-by-1 pixels, transparent) embedded in web pages and cause referer info and cookies to be transferred
Also called web beacons, clear gifs, tracker gifs,etc.
Work just like banner ads from ad networks, but you can’t see them unless you look at the code behind a web page
Also embedded in HTML formatted messages, MS Word documents, etc.
For software to detect web bugs see:

27. How data can be linked
Every time the same cookie is replayed to a site, the site may add information to the record associated with that cookie
Number of times you visit a link, time, date
What page you visit
What page you visited last
Information you type into a web form
If multiple cookies are replayed together, they are usually logged together, effectively linking their data
Narrow scoped cookie might get logged with broad scoped cookie

28. Ad networks search for medical information buy CD
set cookie
replay cookie Ad Ad
Ad company can get your name and address from CD order and link them to your search
Search Service
CD Store

29. What ad networks may know…
Personal data:
address
Full name
Mailing address (street, city, state, and Zip code)
Phone number
Transactional data:
Details of plane trips
Search phrases used at search engines
Health conditions
“It was not necessary for me to click on the banner ads for information to be sent to DoubleClick servers.”
– Richard M. Smith

30. Online and offline merging
In November 1999, DoubleClick purchased Abacus Direct, a company possessing detailed consumer profiles on more than 90% of US households.
In mid-February 2000 DoubleClick announced plans to merge “anonymous” online data with personal information obtained from offline databases
By the first week in March 2000 the plans were put on hold
Stock dropped from $125 (12/99) to $80 (03/00)

31. Offline data goes online…
The Cranor family’s 25 most frequent grocery purchases (sorted by nutritional value)!
The Stop and Shop grocery store began posting purchase information for customers who had frequent shopper cards. Anyone who was aware of a frequent shopper number (printed on receipts) could access a customer’s information if that customer had not yet set a password. This “service” has been discontinued.

32. Steps sites take to protect privacy
Opt-out cookie
DoubleClick
Purging identifiable data from server logs
Amazon.com honor system

33. Behavioral targeting
In 2007/2008, more concerns raised about “behavioral” targeting as a new round of companies started deploying systems to target ads based on previous online behavior
What is the distinction between behavioral and contextual advertising?
How do you implement effective notice and choice?
Where should notice be provided?
Opt-in? Opt-out? When? Where?
Do we need a “do not track” list?
Is it acceptable for ISPs to do this (deep packet inspection)?
Is it acceptable for search engines to do this?