1000 days of UDP amplification DDoS attacks


We presented “1000 days of UDP amplification DDoS attacks” at APWG’s eCrime 2017 conference last week in Scottsdale Arizona. The paper is here, and the slides from Daniel Thomas’s talk are here.

Distributed Denial of Service (DDoS) attacks employing reflected UDP amplification are regularly used to disrupt networks and systems. The amplification allows one rented server to generate significant volumes of data, while the reflection hides the identity of the attacker. Consequently this is an attractive, low risk, strategy for criminals bent on vandalism and extortion. Despite this, many of these criminals have been arrested.

These reflected UDP amplification attacks work by spoofing the source IP address on UDP packets sent from networks that negligently fail to implement BCP38/SAVE. Since UDP (unlike TCP) does not validate the source address, the much larger responses go to the attacker’s intended victim as they spoof the victim’s address on the packets they send out. There are many protocols that can be exploited in this way including DNS and NTP.

To measure the use of this strategy we analysed the results of running a network of honeypot UDP reflectors from July 2014 onwards. We explored the life cycle of attacks that use our honeypots, from the scanning phase used to detect our honeypot machines, through to their use in attacks. We see a median of 1450 malicious scanners per day across all UDP protocols, and have recorded details of 5.18 million subsequent attacks involving in excess of 3.31 trillion packets. We investigated the length of attacks and found that most are very short, but some last for days.

To estimate the total number of attacks that occurred, including those our honeypots did not observe, we used a capture-recapture statistical technique. From this we estimated that our honeypots can see between 85.1% and 96.6% of UDP reflection attacks over our measurement period.

We observe wide variation in the number of attacks per day over the course of the measurement period as attacks using different protocols went in and out of fashion.

This work is ongoing and data from our honeypot network is available to researchers through the Cambridge Cybercrime Centre.

Also, if you want to help stop these attacks being possible you could help CAIDA by
running their spoofer prober software that checks which ISPs are negligently failing to implement BCP38/SAVE.

Configuring Zeus

We presented “Configuring Zeus: A case study of online crime target selection and knowledge transmission” at APWG’s eCrime 2017 conference this past week in Scottsdale Arizona. The paper is here, and the slides from Richard Clayton’s talk are here.

Zeus (sometimes called Zbot) is a family of credential stealing malware which was widely deployed from 2007 to 2012 or so. It belongs to a class of malware dubbed ‘man-in-the-browser‘ (a play on a ‘man in the middle attack’) in that it runs on end-user machines where it can intercept web browser traffic to extract login credentials or to manipulate the page content displayed to the user.

It has been used to attack large numbers of sites, mainly banks — its extreme flexibility is achieved with ‘configuration files’ that indicate which websites are to be targeted, which user submitted fields are to be collected, what webpage rewriting (so called ‘webinjects’) is required and where the results are to be sent.

The complexity of these files seem to have restricted the number of websites actually targeted. In a paper presented at WEIS 2014 Tajalizadehkhoob et al. examined a large number of configuration files and described this lack of development and measured a substantial overlap in the content of different files. As a result, the authors suggested that offenders were not developing configuration files from scratch but were selling, sharing or stealing them.

We decided to test out this conjecture by seeking out messages about Zeus configuration files on underground forums (many of these are have been scraped, leaked or confiscated by law enforcement) — and this paper describes how we found evidence to support all three mechanisms: selling, sharing and stealing.

The paper also gives an account of the history of Zeus with illustrations from the messages that were uncovered along with clear evidence the release of tools to decrypt configuration files by security researchers was also closely followed on the forums, and assisted offenders when it came to stealing configuration files from others.

Inter-ACE national hacking competition today

Over 100 of the best students in cyber from the UK Academic Centres of Excellence in Cyber Security Research are gathered here at the University of Cambridge Computer Laboratory today for the second edition of our annual “Inter-ACE” hacking contest.

The competition is hosted on the CyberNEXS cyber-range of our sponsor Leidos, and involves earning points for hacking into each other’s machines while defending one’s own.   The competition has grown substantially from last year’s: you can follow it live on Twitter (@InterACEcyber) At the time of writing, we still don’t know who is going to take home the trophy. Can you guess who will?

The event has been made possible thanks to generous support from the National Cyber Security Centre, the Cabinet Office, Leidos and NCC Group.

The University is Hiring

We’re looking for a Chief Information Security Officer. This isn’t a research post here at the lab, but across the yard in University Information Services, where they manage our networks and our administrative systems. There will be opportunities to work with security researchers like us, but the main task is protecting Cambridge from all sorts of online bad actors. If you would like to be in the thick of it, and you know what you’re doing, here’s how you can apply.

CfP: BSides London 2017

BSides London 2017
7th June 2017
ILEC Conference Centre, 47 Lillie Road London, SW6 1UD

We invite proposals for BSides London 2017, to be held on the 7th June, 2017 in London, UK.

Please note that all submissions must be submitted at: https://bit.ly/BSidesLDN2017CFP


Important dates

CfP opens – February 14th
CfP closes – March 27th
Voting on CFP Open – March 30th
Voting on CFP Close – April 13th
email notification to proposers – April 14th
Deadline for speakers to confirm attendance – April 21st
BSides London schedule published – May 1st
BSides London! – June 7th, 2017

(All deadlines are 11:59pm GMT)


What is BSides?

Each BSides is a community-driven framework for building events for and by information security community members.  The goal is to expand the spectrum of conversation beyond the traditional confines of space and time.  It creates opportunities for individuals to both present and participate in an intimate atmosphere that encourages collaboration. It is an intense event with discussions, demos, and interaction from participants. It is where conversations for the next-big-thing are happening.



This year our focus will be on a theme that is a fundamental to InfoSec: “Sharing is Caring: Disclosure, leaks as well as knowledge transfer it is all about sharing”. We seek original contributions that present attacks, analyses, designs, applications, protocols, systems, practical experiences, and theory. As usual the theme is not prescriptive, and proposals may include (but are not limited to) the following topics:

* Information technology
* Network security & Cryptography
* Web Application security
* Mobile security
* Usable security
* Virtualization and cloud computing
* Innovative attack / defense strategies
* Forensics / Malware
* Embedded device security / IoT
* Physical security and lockpicking
* Biometrics
* Hardware hacking
* Biohacking and modification
* Open source software
* Robotics (bonus points for bringing an actual robot)
* Massive abuse of technology
* Evolutionary computing
* Ethical and philosophical implications of hacking


Advice to  presenters

PRESENTATIONS should describe novel technical contributions within the scope of the call. The presentations will be subjected to open (non-blind) peer review by the organising committee.  The allotted time for each presentation will typically be between 45 minutes to 1 hour (including Q&A); though shorter presentations are also welcome.

Remember that our participants’ backgrounds and experience are varied. There must be something for everyone, so when choosing a subject go with something you are comfortable with no matter the difficulty level. Your presentation should tell us a story:

– Here is a problem
– It’s an interesting problem
– It’s an unsolved problem
– Here is my idea
– My idea works (details, data)
– Here’s how my idea compares to other people’s approaches

If your talk is not selected, please keep in mind that we aim to provide a “lighting talks” track where speakers can present their topics on a first come/first served basis.

Best of luck and thanks for being part of Security BSides London! For additional information or questions regarding the process please email cfp at securitybsides.org.uk



As in previous years, the schedule for BSides London 2017 will be selected by public vote.

Banks biased against black fraud victims

The following is an op-ed I wrote in today’s Times. It appeared in their Thunderer column.

You’re less likely to be treated fairly by your bank if you’re elderly, poor, female or black. We’ve suspected this for years, and finally The Times has dug up the numbers to prove it.

Fraud victims who’re refused compensation often contact our security research group at Cambridge after they find we work on payment fraud. We call this stream of complaints our ‘fraud telescope’ as it gives us early warning of what the bad guys are up to. We’ve had more than 2,000 cases over 25 years.

In recent years we’ve started to realise what we weren’t seeing. The “dark matter” in the fraud universe is the missing victims: we don’t see that many middle-class white men. The victims who do come to us are disproportionately elderly, poor, female, or black. But crime surveys tell us that the middle classes and the young are more likely to be victims of fraud, so it’s hard to avoid the conclusion that banks are less generous to some of their customers.

We raised the issue of discrimination in 2011 with one of the banks and with the Commission for Racial Equality, but as no-one was keeping records, nothing could be proved, until today.

How can this discrimination happen? Well, UK rules give banks a lot of discretion to decide whether to refund a victim, and the first responders often don’t know the full story. If your HSBC card was compromised by a skimmer on a Tesco ATM, there’s no guarantee that Tesco will have told anyone (unlike in America, where the law forces Tesco to tell you). And the fraud pattern might be something entirely new. So bank staff end up making judgement calls like “Is this customer telling the truth?” and “How much is their business worth to us?” This in turn sets the stage for biases and prejudices to kick in, however subconsciously. Add management pressure to cut costs, sometimes even bonuses for cutting them, and here we are.

There are two lessons. First, banks need to train staff to be aware of unconscious bias (as universities do), and monitor their performance.

Second, the Financial Conduct Authority needs to protect all customers properly. It seems to be moving in the right direction; after the recent fraud against tens of thousands of Tesco Bank account holders, it said it expected fraud victims to be made good immediately. This has been the law in the USA since the 1980s and it must become a firm rule here too.

Government U-turn on Health Privacy

Now that everyone’s distracted with the supreme court case on Brexit, you can expect the government to sneak out something it’s ashamed of. Health secretary Jeremy Hunt has decided to ignore the wishes of over a million people who opted out of having their hospital records given to third parties such as drug companies, and the ICO has decided to pretend that the anonymisation mechanisms he says he’ll use instead are sufficient. One gently smoking gun is the fifth bullet in a new webpage here, where the Department of Health claims that when it says the data are anonymous, your wishes will be ignored. The news has been broken in an article in the Health Services Journal (it’s behind a paywall, as a splendid example of transparency) with the Wellcome Trust praising the ICO’s decision not to take action against the Department. We are assured that “the data is seen as crucial for vital research projects”. The exchange of letters with privacy campaigners that led up to this decision can be found here, here, here, here, here, here, and here.

An early portent of this u-turn was reported here in 2014 when officials reckoned that the only way they could still do administrative tasks such as calculating doctors’ bonuses was to just pretend that the data are anonymous even though they know it isn’t really. Then, after the care.data scandal showed that a billion records had been sold to over a thousand purchasers, we reported here how HES data had also been sold and how the minister seemed to have misled parliament about this.

I will be talking about ethics of all this on Thursday. Even if ministers claim that stolen medical records are OK to use, researchers must not act as if this is true; if patients end up trusting doctors as little as we trust politicians, then medical research will be in serious trouble. There is a video of a previous version of this talk here.

Meanwhile, if you’re annoyed that Jeremy Hunt proposes to ignore not just your privacy rights but your express wishes, you can send him a notice under Section 10 of the Data Protection Act forbidding him from disclosing your data. The Department has complied with such notices in the past, albeit with bad grace as they have no automated way to do it. If thousands of people serve such notices, they may finally have to stand up to the drug company lobbyists and write the missing software. For more, see here.


Last week I gave a keynote talk at CCS about DigiTally, a project we’ve been working on to extend mobile payments to areas where the network is intermittent, congested or non-existent.

The Bill and Melinda Gates Foundation called for ways to increase the use of mobile payments, which have been transformative in many less developed countries. We did some research and found that network availability and cost were the two main problems. So how could we do phone payments where there’s no network, with a marginal cost of zero? If people had smartphones you could use some combination of NFC, bluetooth and local wifi, but most of the rural poor in Africa and Asia use simple phones without any extra communications modalities, other than those which the users themselves can provide. So how could you enable people to do phone payments by simple user actions? We were inspired by the prepayment electricity meters I helped develop some twenty years ago; meters conforming to this spec are now used in over 100 countries.

We got a small grant from the Gates Foundation to do a prototype and field trial. We designed a system, Digitally, where Alice can pay Bob by exchanging eight-digit MACs that are generated, and verified, by the SIM cards in their phones. For rapid prototyping we used overlay SIMs (which are already being used in a different phone payment system in Africa). The cryptography is described in a paper we gave at the Security Protocols Workshop this spring.

Last month we took the prototype to Strathmore University in Nairobi to do a field trial involving usability studies in their bookshop, coffee shop and cafeteria. The results were very encouraging and I described them in my talk at CCS (slides). There will be a paper on this study in due course. We’re now looking for partners to do deployment at scale, whether in phone payments or in other apps that need to support value transfer in delay-tolerant networks.

There has been press coverage in the New Scientist, Engadget and Impress (original Japanese version).