Can we Fix Federated Authentication?

Academic papers, Authentication, Banking security, Legal issues, Protocols, Security economics, Security engineering, Social networks, Web security

My paper Can We Fix the Security Economics of Federated Authentication? asks how we can deal with a world in which your mobile phone contains your credit cards, your driving license and even your car key. What happens when it gets stolen or infected?

Using one service to authenticate the users of another is an old dream but a terrible tar-pit. Recently it has become a game of pass-the-parcel: your newspaper authenticates you via your social networking site, which wants you to recover lost passwords by email, while your email provider wants to use your mobile phone and your phone company depends on your email account. The certification authorities on which online trust relies are open to coercion by governments – which would like us to use ID cards but are hopeless at making systems work. No-one even wants to answer the phone to help out a customer in distress. But as we move to a world of mobile wallets, in which your phone contains your credit cards and even your driving license, we’ll need a sound foundation that’s resilient to fraud and error, and usable by everyone. Where might this foundation be? I argue that there could be a quite surprising answer.

The paper describes some work I did on sabbatical at Google and will appear next week at the Security Protocols Workshop.

Why the Cabinet Office's £27bn cyber crime cost estimate is meaningless

Security economics

Today the UK Cabinet Office released a report written by Detica. The report concluded that the annual cost of cyber crime in UK is £27bn. That’s less than $1 trillion, as AT&T’s Ed Amoroso testified before the US Congress in 2009. But it’s still a very large number, approximately 2% of UK GDP. If the total is accurate, then cyber crime is a very serious problem of utmost national importance.

Unfortunately, much of the total cost is based on questionable calculations that are impossible for outsiders to verify. 60% of the total cost is ascribed to intellectual property theft (i.e., business secrets not copied music and films) and espionage. The report does describe a methodology for how it arrived at the figures. However, several key details are lacking. To calculate the IP and espionage losses, the authors first calculated measures of each sector’s value to the economy. Then they qualitatively assessed how lucrative and feasible these attacks would be in each sector.

This is where trouble arises. Based on these assessments, the authors assigned a sector-specific probability of theft, one for the best-, worst- and average cases. Unfortunately, these probabilities are not specified in the report, and no detailed rationale is given for their assignment. Are the probabilities based on surveys of firms that have fallen victim to these particular types of crime? Or is it a number simply pulled from the air based on the hunch of the authors? It is impossible to determine from the report.
Continue reading Why the Cabinet Office's £27bn cyber crime cost estimate is meaningless →

Measuring password re-use empirically

Authentication, Security engineering, Security psychology, Web security

In the aftermath of Anonymous’ revenge hacking of HBGary over the weekend, some enterprising hackers used one of the stolen credentials and some social engineering to gain root access at rootkit.com, which has been down for a few days since. There isn’t much novel about the hack but the dump of rootkit.com’s SQL databases provides another password dataset for research, though an order of magnitude smaller than the Gawker dataset with just 81,000 hashed passwords.

More interestingly, due to the close proximity of the hacks, we can compare the passwords associated with email addresses registered at both Gawker and rootkit.com. This gives an interesting data point on the widely known problem of password re-use. This new data seems to indicate a significantly higher re-use rate than the few previously published estimates. Continue reading Measuring password re-use empirically →

JPEG canaries: exposing on-the-fly recompression

Academic papers

Many photo-sharing websites decompress and compress uploaded images, to enforce particular compression parameters. This recompression degrades quality. Some web proxies can also recompress images/videos, to give the impression of a faster connection.

In Towards copy-evident JPEG images (with Markus Kuhn, in Lecture Notes in Informatics), we present an algorithm for imperceptibly marking JPEG images so that the recompressed copies show a clearly-visible warning message. (Full page demonstration.)

Original image:

Original image

After recompression:

The image after recompression, with a visible warning message

(If you can’t see the message in the recompressed image, make sure your browser is rendering the images without scaling or filtering.)

Richard Clayton originally suggested the idea of trying to create an image which would show a warning when viewed via a recompressing proxy server. Here is a real-world demonstration using the Google WAP proxy.

Our marking technique is inspired by physical security printing, used to produce documents such as banknotes, tickets, academic transcripts and cheques. Photocopied versions will display a warning (e.g. ‘VOID’) or contain obvious distortions, as duplication turns imperceptible high-frequency patterns into more noticeable low-frequency signals.

Our algorithm works by adding a high-frequency pattern to the image with an amplitude carefully selected to cause maximum quantization error on recompression at a chosen target JPEG quality factor. The amplitude is modulated with a covert warning message, so that foreground message blocks experience maximum quantization error in the opposite direction to background message blocks. While the message is invisible in the marked original image, it becomes visible due to clipping in a recompressed copy.

The challenge remains to extend our approach to mark video data, where rate control and adaptive quantization make the copied document’s properties less predictable. The result would be a digital video that would be severely degraded by recompression to a lower quality, making the algorithm useful for digital content protection.

Another Gawker bug: handling non-ASCII characters in passwords

Authentication, Security engineering, Web security

A few weeks ago I detailed how Gawker lost a million of their users’ passwords. Soon after this I found an interesting vulnerability in Gawker’s password deployment involving the handling of non-ASCII characters. Specifically, they didn’t handle them at all until two weeks ago, instead they were mapping all non-ASCII characters to the ASCII ‘?’ prior to hashing them. This not only greatly limited the theoretical space of passwords, but meant that passwords consisting of any n non-ASCII characters were equivalent to ‘?’^n. Native Telugu or Korean speakers with passwords like ‘రహస్య సంకేత పదం’ or ‘비밀번호’ were vulnerable to an attacker simply guessing a string of question marks. An attacker may in fact know in advance that some users are from non-Latin countries (for example by looking at their email addresses) potentially making this more easily exploitable.

Continue reading Another Gawker bug: handling non-ASCII characters in passwords →

Everyone’s spam is unique

News coverage, Security economics

How much spam you get depends on three main things, how many spammers know (or guess) your email address, how good your spam filtering is, and of course, how active the spammers are.

A couple of years back I investigated how spam volumes varied depending on the first letter of your email address (comparing aardvark@example.com with zebra@example.com), with the variations almost certainly coming down to “guessability” (an email address of john@ is easier to guess than yvette@).

As to the impact of filtering, I investigated spam levels in the aftermath of the disabling of McColo — asking whether it was the easy-to-block spam that disappeared? The impact of that closure will have been different for different people, depending on the type (and relative effectiveness) of their spam filtering solution.

Just at the moment, as reported upon in some detail by Brian Krebs, we’re seeing a major reduction in activity. In particular, the closure of an affiliate system for pharmacy spam in September reduced global spam levels considerably, and since Christmas a number of major systems have practically disappeared.

I’ve had a look at spam data going back to January 2010 from my own email server, which handles email for a handful of domains, and that shows a different story!

It shows that spam was up in October … so the reduction didn’t affect how many of the spam emails came to me, just how many “me’s” there were worldwide. Levels have been below the yearly average for much of December, but I am seeing most (but not all of) the dropoff since Christmas Day.

Click on the graph for an bigger version… and yes, the vertical axis is correct, I really do get up to 60,000 spam emails a day, and of course none at all on the days when the server breaks altogether.

A Merry Christmas to all Bankers

Academic papers, Banking security, Internet censorship, Legal issues, News coverage, Politics, Security engineering

The bankers’ trade association has written to Cambridge University asking for the MPhil thesis of one of our research students, Omar Choudary, to be taken offline. They complain it contains too much detail of our No-PIN attack on Chip-and-PIN and thus “breaches the boundary of responsible disclosure”; they also complain about Omar’s post on the subject to this blog.

Needless to say, we’re not very impressed by this, and I made this clear in my response to the bankers. (I am embarrassed to see I accidentally left Mike Bond off the list of authors of the No-PIN vulnerability. Sorry, Mike!) There is one piece of Christmas cheer, though: the No-PIN attack no longer works against Barclays’ cards at a Barclays merchant. So at least they’ve started to fix the bug – even if it’s taken them a year. We’ll check and report on other banks later.

The bankers also fret that “future research, which may potentially be more damaging, may also be published in this level of detail”. Indeed. Omar is one of my coauthors on a new Chip-and-PIN paper that’s been accepted for Financial Cryptography 2011. So here is our Christmas present to the bankers: it means you all have to come to this conference to hear what we have to say!

Financial Cryptography and Data Security 2011 — Call for Participation

Academic papers, Banking security, Call for papers, Security engineering

Financial Cryptography and Data Security (FC 2011)
Bay Gardens Beach Resort, St. Lucia
February 28 — March 4, 2011

Financial Cryptography and Data Security is a major international forum for research, advanced development, education, exploration, and debate regarding information assurance, with a specific focus on commercial contexts. The conference covers all aspects of securing transactions and systems.

NB: Discounted hotel rate is available only until December 30, 2010

Topics include:

Anonymity and Privacy, Auctions and Audits, Authentication and Identification, Backup Authentication, Biometrics, Certification and Authorization, Cloud Computing Security, Commercial Cryptographic Applications, Transactions and Contracts, Data Outsourcing Security, Digital Cash and Payment Systems, Digital Incentive and Loyalty Systems, Digital Rights Management, Fraud Detection, Game Theoretic Approaches to Security, Identity Theft, Spam, Phishing and Social Engineering, Infrastructure Design, Legal and Regulatory Issues, Management and Operations, Microfinance and Micropayments, Mobile Internet Device Security, Monitoring, Reputation Systems, RFID-Based and Contactless Payment Systems, Risk Assessment and Management, Secure Banking and Financial Web Services, Securing Emerging Computational Paradigms, Security and Risk Perceptions and Judgments, Security Economics, Smartcards, Secure Tokens and Hardware, Trust Management, Underground-Market Economics, Usability, Virtual Economies, Voting Systems

Important Dates

Hotel room reduced rate cut-off: December 30, 2010
Reduced registration rate cut-off: January 21, 2011

Please send any questions to fc11general@ifca.ai

Continue reading Financial Cryptography and Data Security 2011 — Call for Participation →

The Gawker hack: how a million passwords were lost

Authentication, News coverage, Security engineering

Almost a year to the date after the landmark RockYou password hack, we have seen another large password breach, this time of Gawker Media. While an order of magnitude smaller, it’s still probably the second largest public compromise of a website’s password file, and in many ways it’s a more interesting case than RockYou. The story quickly made it to the mainstream press, but the reported details are vague and often wrong. I’ve obtained a copy of the data (which remains generally available, though Gawker is attempting to block listing of the torrent files) so I’ll try to clarify the details of the leak and Gawker’s password implementation (gleaned mostly from the readme file provided with the leaked data and from reverse engineering MySQL dumps). I’ll discuss the actual password dataset in a future post. Continue reading The Gawker hack: how a million passwords were lost →

Wikileaks, security research and policy

Internet censorship, Legal issues, News coverage, Politics, Privacy technology, Security economics, Security engineering

A number of media organisations have been asking us about Wikileaks. Fifteen years ago we kicked off the study of censorship resistant systems, which inspired the peer-to-peer movement; we help maintain Tor, which provides the anonymous communications infrastructure for Wikileaks; and we’ve a longstanding interest in information policy.

I have written before about governments’ love of building large databases of sensitive data to which hundreds of thousands of people need access to do their jobs – such as the NHS spine, which will give over 800,000 people access to our health records. The media are now making the link. Whether sensitive data are about health or about diplomacy, the only way forward is compartmentation. Medical records should be kept in the surgery or hospital where the care is given; and while an intelligence analyst dealing with Iraq might have access to cables on Iraq, Iran and Saudi Arabia, he should have no routine access to stuff on Korea or Brazil.

So much for the security engineering; now to policy. No-one questions the US government’s right to try one of its soldiers for leaking the cables, or the right of the press to publish them now that they’re leaked. But why is Wikileaks treated as the leaker, rather than as a publisher?

This leads me to two related questions. First, does a next-generation censorship-resistant system need a more resilient technical platform, or more respectable institutions? And second, if technological change causes respectable old-media organisations such as the Guardian and the New York Times to go bust and be replaced by blogs, what happens to freedom of the press, and indeed to freedom of speech?