Category Archives: Web security

A Study of Whois Privacy and Proxy Service Abuse

ICANN have now published a draft for public comment of “A Study of Whois Privacy and Proxy Service Abuse“. I am the primary author of this report — the work being done whilst I was collaborating with the National Physical Laboratory (NPL) under EPSRC Grant EP/H018298/1.

This particular study was originally proposed by ICANN in 2010, one of several that were to examine the impact of domain registrants using privacy services (where the name of a domain registrant is published, but contact details are kept private) and proxy services (where even the domain licensee’s name is not made available on the public database).

ICANN wanted to know if a significant percentage of the domain names used to conduct illegal or harmful Internet activities are registered via privacy or proxy services to obscure the perpetrator’s identity? No surprises in our results: they are!

However, it’s more interesting to ask whether this percentage is somewhat higher than the usage of privacy or proxy services for entirely lawful and harmless Internet activities? This turned out NOT to be the case — for example banks use privacy and proxy services almost as often as the registrants of domains used in the hosting of child sexual abuse images; and the registrants of domains used to host (legal) adult pornography use privacy and proxy services more often than most (but not all) of the different types of malicious activity that we studied.

It’s also relevant to consider what other methods might be chosen by those involved in criminal activity to obscure their identities, because in the event of changes to privacy and proxy services, it is likely that they will turn to these alternatives.

Accordingly, we determined experimentally whether a significant percentage of the domain names we examined have been registered with incorrect Whois contact information – and specifically whether or not we could reach the domain registrant using a phone number from the Whois information. We asked them a single question in their native language “did you register this domain”?

We got somewhat variable results from our phone survey — but the pattern becomes clear if we consider whether there is any a priori hope at all of ringing up the domain registrant?

If we sum up the likelihoods:

  • uses privacy or proxy service
  • no (apparently valid) phone number in whois
  • number is apparently valid, but fails to connect
  • number reaches someone other than the registrant

then we find that for legal and harmless activities the probability of a phone call not being possible ranges between 24% (legal pharmacies on the Legitscript list) and 62% (owners of lawful websites that someone has broken into and installed phishing pages). For malicious activities the probability of failure is 88% or more, with typosquatting (which is a civil matter, rather than a criminal one) sitting at 68% (some of the typosquatters want to hide, some do not).

There’s lots of detail and supporting statistics in the report… and an executive summary for the time-challenged. It will provide real data, rather than just speculative anecdotes, to inform the debate around reforming Whois — and the difficulties of doing so.

Revisiting secure introduction via hyperlinks

Today at W2SP I presentednew paper making the case for distributing security policy in hyperlinks. The basic idea is old, but I think the time is right to re-examine it. After the DigiNotar debacle, the community is getting serious about fixing PKI on the web. It was hot topic at this week’s IEEE Security & Privacy (Oakland), highlighted by Jeremy Clark and Paul van Oorschot’s excellent survey paper. There are a slew of protocols under development like key pinning (HPKP), Certificate Transparency, TACK, and others. To these I add s-links, a complementary mechanism to declare support for new proposals in HTML links. Continue reading Revisiting secure introduction via hyperlinks

Current issues in payments (part 2)

With some delay here is the second and final part on our impressions of David Birch’s Tomorrow’s Transactions Forum (TTF13), which we attended thanks to Dave’s generosity (See full agenda and PowerPoint presentations here). See part 1 here.

NOTE: Although written in first person, what follows results from a combination of Laurent Simon’s and my notes.

The theme of day 2 at TTF13 was social inclusion. The kick off question was “How to develop tools to help people deal with money?” (people with no financial culture and based on a transactional account).

This was followed by presentations on “Comic Relief” (the day before ‘the big day’), “Universal Credit” and expert panel on financial inclusion.
Continue reading Current issues in payments (part 2)

Virgin Money sends email helping phishers

It’s not unusual for banks to send emails which are confusingly similar to phishing, but this recent one I received from Virgin Money is exceptionally bad. It tells customers that the bank (Northern Rock) is changing domain names from their usual one ( to and customers should use their usual security credentials to log into the new domain name. Mail clients will often be helpful and change the into a link.

This message is exactly what phishers would like customers to fall for. While this email was legitimate (albeit very unwise), a criminal could follow up with an email saying that savings customers should access their account at (which is currently available for registration). Virgin Money have trained their customers to accept such emails as legitimate, which is a very dangerous lesson to teach.

It would have been safer to not do the rebranding, but if that’s considered essential for commercial reasons, then customers should have been told to continue accessing the site at their usual domain name, and redirected them (via HTTPS) to the new site. It would mean keeping hold of the Northern Rock domain names for the foreseeable future, but that is almost certainly what Virgin Money are planning anyway.

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Plaintext Password Reminders

There was a public outcry followed by ICO “making enquiries” when Troy Hunt published a post about Tesco’s plaintext password reminders exactly a month ago.

I wanted to use the reference for a text I was writing last week when someone asked me about online accounts of Companies House. At that moment I said to myself, wait a second. Companies House sends plaintext reminders as well. How strange. I sent a link to a short post to ComputerWorld. They in turn managed to get a statement from Companies House that includes:

“… although it is [Companies House] certified to the ISO 27001 standard and adheres to the government’s Security Policy Framework, it will carry out a review of its systems in order to establish whether there is a threat to companies’ confidential information.” Continue reading Plaintext Password Reminders

Password cracking, part II: when does password cracking matter?

Yesterday, I took a critical look at the difficulty of interpreting progress in password cracking. Today I’ll make a broader argument that even if we had good data to evaluate cracking efficiency, recent progress isn’t a major threat the vast majority of web passwords. Efficient and powerful cracking tools are useful in some targeted attack scenarios, but just don’t change the economics of industrial-scale attacks against web accounts. The basic mechanics of web passwords mean highly-efficient cracking doesn’t offer much benefit in untargeted attacks. Continue reading Password cracking, part II: when does password cracking matter?

Password cracking, part I: how much has cracking improved?

Password cracking has returned to the news, with a thorough Ars Technica article on the increasing potency of cracking tools and the third Crack Me If You Can contest at this year’s DEFCON. Taking a critical view, I’ll argue that it’s not clear exactly how much password cracking is improving and that the cracking community could do a much better job of measuring progress.

Password cracking can be evaluated on two nearly independent axes: power (the ability to check a large number of guesses quickly and cheaply using optimized software, GPUs, FPGAs, and so on) and efficiency (the ability to generate large lists of candidate passwords accurately ranked by real-world likelihood using sophisticated models). It’s relatively simple to measure cracking power in units of hashes evaluated per second or hashes per second per unit cost. There are details to account for, like the complexity of the hash being evaluated, but this problem is generally similar to cryptographic brute force against unknown (random) keys and power is generally increasing exponentially in tune with Moore’s law. The move to hardware-based cracking has enabled well-documented orders-of-magnitude speedups.

Cracking efficiency, by contrast, is rarely measured well. Useful data points, some of which I curated in my PhD thesis, consist of the number of guesses made against a given set of password hashes and the proportion of hashes which were cracked as a result. Ideally many such points should be reported, allowing us to plot a curve showing the marginal returns as additional guessing effort is expended. Unfortunately results are often stated in terms of the total number of hashes cracked (here are some examples). Sometimes the runtime of a cracking tool is reported, which is an improvement but conflates efficiency with power. Continue reading Password cracking, part I: how much has cracking improved?

Call for Papers: eCrime Researchers Summit

I have the privilege of serving as co-chair of the program committee for the Anti-Phishing Working Group’s eCrime Researchers Summit, to be held October 23-24 in Las Croabas, Puerto Rico. This has long been one of my favorite conferences to participate in, because it is held in conjunction with the APWG general meeting. This ensures that participation in the conference is evenly split between academia and industry, which leads to in-depth discussions of the latest trends in online crime. It also provides a unique audience for academic researchers to discuss their work, which can foster future collaboration.

Some of my joint work with Richard Clayton appearing at this conference has been discussed on this blog, from measuring the effectiveness of website take-down in fighting phishing to uncovering the frequent lack of cooperation between security firms. As you will see from the call for papers, the conference seeks submissions on all aspects of online crime, not just phishing. Paper submissions are due August 3, so get to work so we can meet up in Puerto Rico this October!
Continue reading Call for Papers: eCrime Researchers Summit

On the (alleged) LinkedIn password leak

UPDATE 2012-06-07: LinkedIn has confirmed the leak is real, that they “recently” switched to salted passwords (so the data is presumably an out-of-date backup) and that they’re resetting passwords of users involved in the leak. There is still no credible information about if the hackers involved have the account names or the rest of the site’s passwords. If so, this incident could still have serious security consequences for LinkedIn users. If not, it’s still a major black eye for LinkedIn, though they deserve credit for acting quickly to minimise the damage.

LinkedIn appears to have been the latest website to suffer a large-scale password leak. Perhaps due to LinkedIn’s relatively high profile, it’s made major news very quickly even though LinkedIn has neither confirmed nor denied the reports. Unfortunately the news coverage has badly muddled the facts. All I’ve seen is a list 6,458,020 unsalted SHA-1 hashes floating around. There are no account names associated with the hashes. Most importantly the leaked file has no repeated hashes. All of the coverage appears to miss this fact. Most likely, the leaker intentionally ran it through ‘uniq’ in addition to removing account info to limit the damage. Also interestingly, 3,521,180 (about 55%) of the hashes have the first 20 bits over-written with 0. Among these, 670,785 are otherwise equal to another hash, meaning that they are actually repeats of the same password stored in a slightly different format (LinkedIn probably just switched formats at some point in the past). So there are really 5,787,235 unique hashes leaked. Continue reading On the (alleged) LinkedIn password leak

Of contraseñas, סיסמאות, and 密码

Over a year ago, we blogged about a bug at Gawker which replaced all non-ASCII characters in passwords with ‘?’ prior to checking. Along with Rubin Xu and others I’ve investigated issues surrounding passwords, languages, and character encoding throughout the past year. This should be easy: websites using UTF-8 can accept any password and hash it into a standard format regardless of the writing system being used. Instead though, as we report a new paper which I presented last week at the Web 2.0 Security and Privacy workshop in San Francisco, passwords still localise poorly both because websites are buggy and users have been trained to type ASCII passwords only. This has broad implications for passwords’ role as a “universal” authentication mechanism. Continue reading Of contraseñas, סיסמאות, and 密码