Buyer Beware: Online Shopping Hazards Exposed By Computer Scientist
Consumers who shop online may be risking their privacy with every purchase, contends University of Massachusetts Amherst computer scientist Kevin Fu. His research suggests that a confluence of factors, including the widespread use of cookies and demand for quick and easy transactions, results in Web sites that are often insecure.
鈥淢uch Web security rests on illusion and hope,鈥� says Fu, who discussed how Web sites leak private information on Saturday, Feb. 18 at the American Association for the Advancement of Science meeting in St. Louis.
Most Web users have heard of cookies, the small chunks of information that a Web server sends to a browser to identify the user at a later date. Cookies are stored on the browser computer鈥檚 hard drive and each time a user revisits a site the cookie is sent back to the server, telling it, 鈥淗i, it鈥檚 me again.鈥�
鈥淐ookies are insecure, no matter what you do,鈥� says Fu. While they aren鈥檛 that dangerous when used for things like storing preferences on personalized Web pages (they are how Yahoo remembers that a user wants science headlines displayed, for example) they are also employed to authenticate users who are shopping online. It鈥檚 these so-called 鈥渁uthentication cookies鈥� that are often exploitable, says Fu.
Cookies work by replaying the same information. While they may be associated with a password to start, the cookie is how a site remembers a user, and allows them to skip a log-in page. So someone who has accessed a series of cookies on a hard drive can look for a pattern and then backtrack to come up with the algorithm that generated them. 鈥淚t鈥檚 the kind of thing a bored teenager could do in a few hours,鈥� says Fu.
Cookies aren鈥檛 the only problem, says Fu. Every Web site has its own method of authenticating users, and there is no set standard for Web site security鈥攅ven that little padlock icon doesn鈥檛 mean much, he says. Many sites use what Fu calls 鈥渉ome-brew cryptography,鈥� a security system that鈥檚 set up by someone lacking the expertise to do so. In recent years some companies have begun selling off-the-shelf encryption toolkits. These can be more secure, says Fu, but many are 鈥渏ust smoke and mirrors.鈥�
Unless a security system has 鈥渙pen design,鈥� meaning how it works is public information, it probably isn鈥檛 worth much, says Fu. The best log-in methods don鈥檛 employ cookies, but use what鈥檚 known as client certificates in SSL or 鈥渟ecure socket layer.鈥� These are akin to a signet ring, says Fu. The user authenticates who they are by stamping the wax with their seal. They never actually send the ring itself to the site鈥攚hich is what cookies do. These systems are often used at universities, allowing students to access grades online, for example.
Why aren鈥檛 client certificates used elsewhere? They are cumbersome, says Fu, and retailers want to offer quick, easy shopping. Cookies get the most sales in the shortest time, and if no one is attacking, they work just fine. Being able to order something quickly provides short-term fulfillment, and the long-term cost to privacy isn鈥檛 very tangible.
There are steps that companies can take to prevent attackers from breaking their authentication schemes, says Fu. Prohibiting guessable passwords, for example, or only using temporary cookies that expire when the user exits the browser. A cryptographic system with a public protocol that can be reviewed for flaws will likely be more secure than a system with a private one.
Fu does shop online. 鈥淭here isn鈥檛 much of an alternative for consumers. Even if you shop by phone, the attendant often enters your data on the same Web page you are trying to avoid,鈥� he says. A CEO, a doctor or someone with access to the records of others should especially care about secure log-ins.
鈥淭here鈥檚 a lot of legacy to this, too,鈥� he adds, 鈥淭he set-up is too entrenched at this point鈥攖oo many hours and too much money would be required to change things. But the company that figures out how to do so will be very successful.鈥�
Source: University of Massachusetts Amherst
