Jefferson’s Wheel

KIRO TV (Seattle) has a story on RFID privacy issues: Credit Cards Stolen Without Leaving Wallet (it includes a video demonstration).

German-born Karsten Nohl is a security consultant and PhD student at the University of Virginia. He was in Seattle recently to speak at a technology conference and is known worldwide for hacking into transit systems.

He’s exposed significant security problems with transit cards commuters were told held their personal information secure, but Nohl showed, did not

“Is it all that inconvenient to swipe a card? Does it really have to be tapping? Would, for that perhaps tiny added benefit, now expose your data to everybody in your vicinity? Perhaps not. So, that is a discussion that has to be had. And not just by the companies introducing something new and fancy and forcing everybody to use it, but rather by the consumers, too,” said Nohl.

Kim Hart has written an article covering Adrienne Felt’s study of privacy issues with Facebook applications: A Flashy Facebook Page, at a Cost to Privacy: Add-Ons to Online Social Profiles Expose Personal Data to Strangers, The Washington Post, 12 June 2008.

Ben Ling, director of Facebook’s platform, said that developers are not allowed to share data with advertisers but that they can use it to tailor features to users. Facebook now removes applications that abuse user data by, for example, forcing members to invite all of their friends before they can use it.

“When we find out people have violated that policy, there is swift enforcement,” he said.

But it is often difficult to tell when developers are breaking the rules by, for example, storing members’ data for more than 24 hours, said Adrienne Felt, who recently studied Facebook security at the University of Virginia.

She examined 150 of the most popular Facebook applications to find out how much data could be gathered. Her research, which was presented at a privacy conference last month, found that about 90 percent of the applications have unnecessary access to private data.

“Once the information is on a third-party server, Facebook can’t do anything about it,” she said. Developers can use it to provide targeted ads based on a member’s gender, age or relationship status.

The article also appeared in MSNBC, the Kansas City Star, the Los Angeles Times (Facebook widgets pose privacy risks:Users often give away their personal data and that of friends without knowing when they install the popular social network programs), the Austin American-Statesman (Social networking applications could become a privacy headache), and the Washington Post’s Express edition (FreeRide Lunchtime Reading: Who’s Getting in Your Facebook?).

Electronic Design has an interview with me: Electronic Design Interviews U. of Virginia Computer Prof, Electronic Design, 21 May 2008. The interview focuses on the history of Splint, and the current state and future of program analysis tools.

Another XSS vulnerability has been discovered in Facebook, as reported by InformationWeek (George Hulme). The posting also links to Adrienne Felt’s Facebook security work.

Our upcoming USENIX Security Symposium paper is now available: Reverse-Engineering a Cryptographic RFID Tag by Karsten Nohl, David Evans, Starbug, and Henryk Plötz.

The paper describes the methods used to reverse engineering the encryption on the Mifare Classic RFID tag and some of the things we learned by doing it. Karsten Nohl will present the paper at the USENIX Security Symposium in San Jose on July 31.

Abstract

The security of embedded devices often relies on the secrecy of proprietary cryptographic algorithms. These algorithms and their weaknesses are frequently disclosed through reverse-engineering software, but it is commonly thought to be too expensive to reconstruct designs from a hardware implementation alone. This paper challenges that belief by presenting an approach to reverse-engineering a cipher from a silicon implementation. Using this mostly automated approach, we reveal a cipher from an RFID tag that is not known to have a software or micro-code implementation. We reconstruct the cipher from the widely used Mifare Classic RFID tag by using a combination of image analysis of circuits and protocol analysis. Our analysis reveals that the security of the tag is even below the level that its 48-bit key length suggests due to a number of design flaws. Weak random numbers and a weakness in the authentication protocol allow for pre-computed rainbow tables to be used to find any key in a matter of seconds. Our approach of deducing functionality from circuit images is mostly automated, hence it is also feasible for large chips. The assumption that algorithms can be kept secret should therefore to be avoided for any type of silicon chip.

Full paper (9 pages): [PDF] [HTML]

Nathanael Paul’s PhD dissertation has been approved! He will graduate this Sunday.

The dissertation is available here: Disk-Level Malware Detection [Abstract] [Full text: PDF, 155 pages].

Congratulations, Nate! (That is, “Dr. Paul”.) Nate is currently a post-doctoral fellow at Vrije Universiteit, Amsterdam working with Andrew Tanenbaum.

Our paper, Privacy Protection for Social Networking Platforms by Adrienne Felt and David Evans is now available [PDF]. Adrienne Felt will present the paper at the Web 2.0 Security and Privacy 2008 (in conjunction with 2008 IEEE Symposium on Security and Privacy) in Oakland, CA on May 22, 2008.

Abstract

Social networking platforms integrate third-party content into social networking sites and give third-party developers access to user data. These open interfaces enable popular site enhancements but pose serious privacy risks by exposing user data to third-party developers. We address the privacy risks associated with social networking APIs by presenting a privacy-by-proxy design for a privacy-preserving API. Our design is motivated by an analysis of the data needs and uses of Facebook applications. We studied 150 popular Facebook applications and found that nearly all applications could maintain their functionality using a limited interface that only provides access to an anonymized social graph and placeholders for user data. Since the platform host can control the third party applications’ output, privacy-by-proxy can be accomplished by using new tags and data transformations without major changes to either the platform architecture or applications.

Full paper (8 pages): [PDF]
Project Website

[Added 25 May]: Talk slides (by Adrienne Felt): [PDF]

Our paper, Hiding in Groups: On the Expressiveness of Privacy Distributions by Karsten Nohl and David Evans, is now available: PDF (15 pages). Karsten Nohl will present the paper at the 23^rd International Information Security Conference (SEC 2008, Co-located with IFIP World Computer Congress 2008) in Milan, Italy, 8-10 September 2008.

Abstract

Many applications inherently disclose information because perfect privacy protection is prohibitively expensive. RFID tags, for example, cannot be equipped with the cryptographic primitives needed to completely shield their information from unauthorized reads. All known privacy protocols that scale to the anticipated sizes of RFID systems achieve at most modest levels of protection. Previous analyses found the protocols to have weak privacy, but relied on simplifying attacker models and did not provide insights into how to improve privacy. We introduce a new general way to model privacy through probability distributions, that capture how much information is leaked by different users of a system. We use this metric to examine information leakage for an RFID tag from the a scalable privacy protocol and from a timing side channel that is observable through the tag’s random number generator. To increase the privacy of the protocol, we combine our results with a new model for rational attackers to derive the overall value of an attack. This attacker model is also based on distributions and integrates seamlessly into our framework for information leakage. Our analysis points to a new parameterization for the privacy protocol that significantly improves privacy by decreasing the expected attack value while maintaining reasonable scalability at acceptable cost.

Full paper (15 pages): [PDF]

Extended Technical Report (18 pages): [PDF]

The Associated Press has an article by Martha Irvine, Social networking applications can pose security risks, that is based on Adrienne Felt’s analysis of Facebook platform privacy.

Still, it’s an honor system, says Adrienne Felt, a computer science major at the University of Virginia. A Facebook user herself, she decided to research the site’s applications and even created her own so she could see how it worked.

Most of the developers Felt polled said they either didn’t need or use the information available to them and, if they did, accessed it only for advertising purposes.

But, in the end, Felt says there’s really nothing stopping them from matching profile information with public records. It also could be sold or stolen. And all of that could lead to serious matters such as identity theft.

“People seem to have this idea that, when you put something on the Internet, there should be some privacy model out there — that there’s somebody out there that’s enforcing good manners. But that’s not true,” Felt says.

(Note: there wasn’t actually any “polling” of developers, just examining what applications do to determine how they appeared to use information.)

The story has been picked up by some other places including BusinessWeek, CNNMoney (From games to virtual gifts, social networking applications popular — but at what risk?), Forbes, International Herald Tribune, National Public Radio, San Jose Mercury News, Philadelphia Inquirer, Las Vegas Sun, Fort Worth Star-Telegram, Houston Chronicle, San Francisco Chronicle, Seattle Post-Intelligencer, MyFOX, and The Sydney Morning Herald.

The Colorado Daily wins the best title award for MySpace is your space (and yours, and yours…) (but its the same story).

Pantagraph (Central Illinois) has it currently as their top article and includes a picture their front page.

[Added 13 May] Pew Internet and American Life Project has a post on this: Securing Private Data from Network ‘Zombies’ by Mary Madden.

My shameless self-searching google alert occasionally turns up interesting things, like this letter to the editor of the Huntington News (West Virginia) by Gary Hurd. It refutes an op-ed piece that made all sorts of crazy pseudo-scientific arguments for “intelligent design”. The letter refutes one of the specific claims in the argument about the complexity of DNA using some material found in a lecture for my CS201J course:

And is this notion that human DNA is more complex than “any program ever devised” actually factual? The book by Watson was published in 1965, and the book by Gates that Ashby is misquoting was published in 1995, before the human genome project when we did not even know how many genes humans had! At the time, Gates’ statement was entirely reasonable, even though there was no actual data to test it. But Ashby makes a further claim, “… it is a well known fact that human DNA contains more organized information than the largest set of encyclopedias ever in print.”

David Evans, Professor of Computer Science at the University of Virginia has made some interesting comparisons between DNA and today’s computer software as part of his Computer Science 201: Engineering Software course. Let’s begin with his observation that complexity of computer software has grown at an amazing rate in the last 40 years (about since Watson’s book on the gene was published). The Apollo mission guidance programs had about 36,000 instructions, but today’s Windows XP made by Bill Gates’ Microsoft has about fifty million instructions! Professor Evans then compares this to what we now know about genes. For example, the smallest known set of genes of an organism belong to a bacterial parasite called Nanoarchaeum equitans which has 522 genes representing about 40,000 bytes of information. In other terms, it is slightly larger than the Apollo guidance system. The human genome, or as Evans called it “The Make-Human Program,” has a total of about 3 billion base pairs, which entail about 35 thousand genes. The total information content counting all of the bases is 750 megabytes, or just larger than the 650 megabytes that fit on your CDs at home. But, we have learned that massive amounts of human DNA are genetic “left overs,” non-coding segments and duplications. In short, Human DNA has fewer working instructions than Windows software, and even its total 3 billion bases are tiny compared to Wal-Mart’s 280 terabyte database (the equivalent of 1,120,000 billion DNA bases).

Like most antiscience, Ashby’s “well known facts” are not facts.

The lecture he is referring to is here: Lecture 23: Everything Else You Should Know (but won’t see on Exam 2) [PPT] (slides 18-26). Although I am happy to have anything I’ve done used to debunk intelligent design, the point I meant to make here is a bit different from what Dr. Hurd’s letter is claiming — I am not intending to suggest that the genome is not a complex program (since one could still claim it results in executions that are still far more complex, resillient, and sophisticated than anything humans have created), just that its encoding is incredibly expressive in order for such complex outcomes to be encoded with so little information. Of course, a lot of the information is not in the genome itself, but in the very complex biochemical operating system in which it is interpreted.

The specific claim from the original op-ed piece, that “DNA contains more organized information than the largest set of encyclopedias ever in print”, of course, is blatantly false. A few image-laden pages of a World Book volume contain far more information that the entire human genome.