Talking at mrmcds 2016 in Darmstadt, Germany

A couple of weeks ago, I attended the mrmcds in Darmstadt, Germany. Just like I did the last years. Like the years before, the conference was nicely themed. This year, the theme was all things medical. So speakers were given doctors’ coats, conference staff were running around like surgeons, alcohol could be had intravenously …

mrmcd 2016 logo

The talk on medical device nightmares (video) showed some medical devices like which show and record vital signs such as the pulse or blood pressure. But also more fancy devices such as an MRI. Of course, he did not only show the devices themselves, but rather how they tested them on their external interfaces, i.e. the networking port. Speaking of the MRI: It exposed a few hundred open ports. The services listening on these ports crashed when nmap scanned the host… But at least apparently they recovered automatically. He also presented an anaesthetic monitoring device, which is supposed to show how much alive a patient still is. The device seems to have a telnet interface which you can log on to with default credentials. The telnet interface has, not surprisingly, a command injection vulnerability, which allowed them to take ownership of the device. The next step was then to hijack the framebuffer and to render whatever they wanted on it. For example nice looking vital data; as if the patient was still alive. Or, probably the more obvious thing to do: Show Rick Astley.

It’s been an entertaining talk which makes you realise how complicated the whole area of pharmaceutical or medical appliances is. They need to go through a long and troublesome certification process, not unlike other businesses (say, car manufacturers). Patching the underlying Windows is simply not possible without losing the certification. You may well ask whether a certificate or an up-to-date OS is better for your health. And while I make it look a bit ridiculous now, I do appreciate that it’s a tough subject.

My own talk on GNOME (video) was well visited. I explained why I think GNOME is a good candidate for shipping security software to the masses. I said that GNOME cares about its users and goes the extra mile to support as many users as possible. That includes making certain decisions to provide a secure by default system. I gave two examples of how I think GNOME pushes the envelope when it comes to making security usable. One was the problem of OpenPGP Keysigning. I mentioned that it’s a very geeky thing which mortals do not understand. Neither do many security people, to be honest. And you can’t even blame them because it’s a messy thing to do. Doing it properly™ involves a metric ton of OpSec to protect the integrity of the key to be signed. I think that we can make the process much more usable than it is right now while even maintaining security. This year, I had Andrei working with me to make this happen.

The other example I gave was the problem of USB security. Do you know when you use your USB? And do you know when you don’t? And do you know when other people use your USB? I talked about the possibility to lock down your USB ports while you’re not in front of your computer. The argument goes that you can’t possibly insert anything if you’re away. Of course, there are certain cases to keep in mind, like not forbidding a keyboard to be plugged in, in case the old one breaks. But there is little reason to allow your USB camera to work unless you are actively using your machine. I presented how this could look like by showing off the work the George did last summer.

My friend Jens talked about Reverse Engineering of applications. He started to explain why you would do that in first place. Analysing your freshly received malware or weaknesses (think backdoors or bypasses) in your software are motivations, he said. But you might as well tinker with old software which has no developer anymore or try to find APIs of other software for interoperational purposes, he said. Let me note that with Free Software, you wouldn’t have to reverse engineer the binary ;-) But he also mentioned that industrial espionage is a reason for people to reverse engineer a compiled programme. The tool he uses the most is the “file” tool. He went on to explain the various executable formats for various machine flavours (think: x86, ELF, PE, JVM). To go practical, he showed a .NET application which only writes “hello, world!”, because malware, he said, is written in .NET nowadays. In order to decompile the binary he recommended “iLspy” as a one-stop suite for reverse engineering .NET applications. Next up were Android applications. He showed how to pull the APK off the device and how to decompose it to JAR classes. Then he recommended CFR for decompiling those into Java code. His clients, mostly banks, he said, try to hide secret keys in their apps, so the first thing he does when having a new job is to grep for “secret”. In 80% of the cases, he said, it is successful. To make it harder for someone to reverse engineer the binary, obfuscators exist for Java, but also for C. He also mentioned some anti debugging techniques such as to check for the presence of certain DLLs or to throw certain interrupts to determine whether the application runs under a debugger. It was a very practical talk which certainly made it clear that the presented things are relevant today. Due to the limited time and the many examples, he could only scratch the surface, though.

It’s been a nice conference with 400ish attendees. I really like how they care about the details, also when it comes to make the speakers feel good. It’s too sad that it’s only one weekend. I’m looking forward to attending next year’s edition :-)

mrmcd 2015

I attended this year’s mrmcd, a cozy conference in Darmstadt, Germany. As in the previous years, it’s a 350 people event with a relaxed atmosphere. I really enjoy going to these mid-size events with a decent selection of talks and attentive guests.

The conference was opened by Paolo Ferri’s Keynote. He is from the ESA and gave a very entertaining talk about the Rosetta mission. He mentioned the challenges involved in launching a missile for a mission to be executed ten years later. It was very interesting to see what they have achieved over a few hundred kilometers distance. Now I want to become a space pilot, too ;-)

The next talk was on those tracking devices for your fitness. Turns out, that these tracking devices may actually track you and that they hence pose a risk for your privacy. Apparently fraud is another issue for insurance companies in the US, because some allow you to get better rates when you upload your fitness status. That makes those fitness trackers an interesting target for both people wanting to manipulate their walking statistics to get a better premium for health care and attackers who want to harm someone by changing their statistics.

Concretely, he presented, these devices run with Bluetooth 4 (Smart) which allows anyone to see the device. In addition, service discovery is also turned on which allows anyone to query the device. Usually, he said, no pin is needed anymore to connect to the device. He actually tested several devices with regard to several aspects, such as authentication, what data is stored, what is sent to the Internet and what security mechanisms the apps (for a phone) have been deployed. Among the tested devices were the XiaomMi Miband, the Fitbit, or the Huawei TalkBand B1. The MiBand was setting a good example by disabling discovery once someone has connected to the device. It also saves the MAC address of the phone and ignores others. In order to investigate the data sent between a phone and a band, they disassembled the Android applications.

Muzy was telling a fairytale about a big data lake gone bad.
He said that data lakes are a storage for not necessarily structured data which allow extraction of certain features in an on-demand fashion and that the processed data will then eventually end up in a data warehouse in a much more structured fashion. According to him, data scientists then have unlimited access to that data. That poses a problem and in order to secure the data, he proposed to introduce another layer of authorization to determine whether data scientists are allowed to access certain records. That is a bit different from what exists today: Encrypt data at rest and encrypt in motion. He claimed that current approaches do not solve actual problems, because of, e.g. key management questions. However, user rights management and user authorization are currently emerging, he said.

Later, he referred on Apache Spark. With big data, he said, you need to adapt to a new programming paradigm away from a single worker to multiple nodes, split up work, handling errors and slow tasks. Map reduce, he said, is one programming model. A popular framework for writing in a such a paradigm is Apache’s Hadoop, but there are more. He presented Apache Spark. But it only begins to make sense if you want to analyse more data than you can fit in your RAM, he said. Spark distributes data for you and executes operations on it in a parallel manner, so you don’t need to care about all of that. However, not all applications are a nice fit for Spark, he mentioned. He gave high performance weather computations as such as example. In general, Spark fits well if IPC not required.

The conference then continued with two very interesting talks on Bahn APIs. derf presented on public transport APIs like EFA, HAFAS, and IRIS. These APIs can do things like routing from A to B or answer questions such as which trains are running from a given station. However, these APIs are hardly documented. The IRIS-system is the internal Bahn-API which is probably not supposed to be publicly available, but there is a Web page which exposes (bits) of the API. Others have used that to build similar, even more fancy things. Anyway, he used these APIs to query for trains running late. The results were insightful and entertaining, but have not been released to the general public. However, the speakers presented a way to query all trains in Germany. Long story short: They use the Zugradar which also contains the geo coordinates. They acquired 160 millions datasets over the last year which is represented in 80GB of JSON. They have made their database available as ElasticSearch and Kibana interface. The code it at Github. That is really really good stuff. I’m already in the process of building an ElasticSearch and Spark cluster to munch on that data.

Yours truly also had a talk. I was speaking on GNOME Keysign. Because the CCC people know how to run a great conference, we already have recordings (torrent). You get the slides here. Those of you who know me don’t find the content surprising. To all others: GNOME Keysign is a tool for signing OpenPGP Keys. New features include the capability to sign keys offline, that is, you present a file with a key and you have it signed following best practices.

Another talk I had, this time with a colleague of mine, was on Searchable Encryption. Again, the Video already exists. The slides are probably less funny than they were during the presentation, but hopefully still informative enough to make some sense out of them. Together we mentioned various existing cryptographic schemes which allow you to have a third party execute search operations on your encrypted data on your behalf. The most interesting schemes we showed were Song, Wagner, Perrig and Cash et al..

Thanks again to the organisers for this nice event! I’m looking forward to coming back next year.

mrmcd14 in Darmstadt – DOM-based XSS

After last year’s fabulous event, I was really looking forward to this year’s mrmcd in Darmstadt, Germany. It outgrew last year’s edition and had probably around 250 to 300 people attending. Maybe even more. In fact, 450 clients generated 423 GB traffic during the conference which lasted 60 hours or so. That’s around 2MB/s. That’s megabytes. Per second. Every second. I find that quite impressive. Especially as the outdoor area was very inviting to just hang around, grab a beer, and chat to your fellow hackers. So some people must have had an amazing demand of … updates…

This year’s theme was construction sites. As IT, and especially security, is a major, never ending, and dangerous construction site. It was well done, with a lot of warning tape, the people wearing helmets, hi-vis vests, some security boots, etc. Although it couldn’t excel last year’s aviation theme, but the watermark was set extremely high. Anyway, the speakers received cool gadgets, like a tool set, a level, and other very well done gadgets. The talks were opened by Unicorn who, as you can see, was wearing proper safety gear. We were given instructions as to how to behave in case of fire, flood, or lack of alcohol. A nifty feature of this event is the availability of carbo hydrates in form of various food stuffs. It’s very cool to always being able to walk up to the buffet and fill up energy reserves.

The keynote was involuntarily given by dodger who did not miss the opportunity to show us various constructions sites, such as the Utah Data Center. Ultimately, (now I am maybe over interpreting things), it’s also hackers like us who make those possible. We usually decide for ourselves where to go and what to do. It was a good round-up on how we as a community work or should work. Also with some political references which I think is important as I have the feeling that many people lose that focus too easily.

An interesting series of talks was given by Ange Albertini, who first presented the PDF file format. It was interesting to see how the format actually looks like. I knew already a little but I’ve never really cared about the details. This was a very interesting and visually appealing talk. Pretty much like his other presentations which were again on file formats and on crypto.

My own talk was scheduled after the second night. I was positively surprised to see a half-filled room on a Sunday morning, after two nights of demanding partying… Anyway, I had an interested crowd which I think I could entertain. You can find my slides here. I was talking on DOM-based Cross-site Scripting. I presented a modified Chrome browser which is able to stop all identified DOM-based XSSs. I will need a separate post to cover the details. As a brief summary: Both WebKit and V8 were modified to track taint, that is, to annotate strings with the information of the source. Such a source could be the document.URL or the This taint information is evaluated whenever it is about to be compiled to code. The simple approach of blocking every tainted string to compile is not followed as it breaks the Web. Instead, the compiler will notice which token is about to be generated and only allow generation if and only if the string is untainted or of a data type (String, Boolean, Number). If the tainted token is, for example, function call, assignment or pretty much anything else, then it is replaced with an illegal token in order to abort compilation. There is a video of the talk here:

As we are on videos, the video team is just plainly amazing. It released videos of the event pretty much after they finished. And in a quality that is hard to excel. You check the videos of this conference, but also others. You may find some gems that are well worth watching. Be aware though, some talks are also very much on the vapor-ware side of things… I guess I don’t need to point to specific talks as it should be easy to identify…

I am already looking forward to next year’s event. The watermark has, again, been set high and I expect the next year to be able to raise that bar. But I hope it will be able to stay small enough to not lose the cosy and comfy feeling. Maybe I shouldn’t blog about that fantastic event to not generate too much attention ;-)


It’s been a while since I attended the mrmcds. In 2011 the event did not take place and I couldn’t make it the year after. Fortunately, 2013 allowed me to participate and I was heavily surprised by the quality of everything. The (newish) location, the people, the provided catering, the atmosphere, …

wlan stats

The event itself is relatively small. I don’t have numbers but I felt like being surrounded by 100 people. Although the stats about connected devices suggests there were at least twice or thrice as many people present.


The talks were good, a refreshing mix of technical and non-technical content. With an audience generally inclined to discuss things. That allowed for more lively sessions which create new insights, also for the speakers. My favourite was Akiko talking about her job as air traffic controller. I learned a lot about how the aviation industry is organised how various pieces fit together.

fukami doro

Fukami keynoted the conference and tried to make us aware of our ethics. Surveillance was made by hackers, he said. People like you and me. The exercise for the audience was to further think and conclude that if we didn’t help implementing and deploying surveillance infrastructure, it wouldn’t have gotten that bad. While the talk itself wasn’t too bad, I wonder who the target audience was. If it meant to wake up young hackers who have not yet adjusted their moral compass, it was too weak. The talk didn’t really give advice as to how to handle dubious situations. If it was not meant for those hackers, then why talk about it in a very basic way and not ask hard questions? Anyway, I enjoyed seeing the issue of people’s responsibility coming up and creating a discussion among the hackers.

Enjoy Cock

Mine and Stef’s talk went well, although it was the in the very last slot of the conference. After two long party nights. I barely made it to the talk myself :D We presented new ideas to guide the user when it comes to security critical questions. If you have been to GUADEC, then you haven’t missed much. The talk got a slight new angle though. In case you are interested in the slides, you can find them here.


The design of the conference was very impressive. The theme was aviation and not only did we have an impressive talk monitor as seen above, we also had trolleys with drinks and food as well as the time for various interesting locations. We also received amazing gadgets like the laser engraved belt made from the typical air plane seatbelt.

As always, parties were had with own DJs, light show, beer straight from the tap, cool people and music. To summarize: I’m glad to have visited a very enjoyable event. It’s a pleasure to be around all those smart hackers and to have inspiring discussions. I’m looking forward to next year.


mrmcd1001b Impressions

I had the pleasure to be invited to the MetaRheinMain ChaosDays 1001b (mrmcd1001b) in Darmstadt. This years motto was “Beyond Science Fiction” and ~250 people gathered together to discuss “Society and Technology in 20th century fiction and 21th century reality”.  

The presented talks were mostly interesting, although I didn’t attend that many. I spent most of the time talking to people or giving (two) talks myself: Security in Mobile Devices and Virtualised USB Fuzzing.

The first one went as expected and I think the attendees enjoyed it very much. Again, talking about technical details that a buffer overflow on x86 involves is not that much fun but I think it went at least alrightish. Slides can be found here.

The second talk was kind of a rehearsal for my final thesis presentation. So I took the chance to prepare myself for Dublin and present brand new stuff^tm. I started off crashing a Linux PC with my N900 and went then to the talk. It was a bit confusing, I guess. But in fairness: It was very late in every sense of the word ;-) But I got positive feedback nonetheless so it’s better if you make up your own mind with the slides. Although I don’t think the slides alone are that interesting.

For some reason, people were interested in the commands that I’ve used for the demo:

  1. Boot Ubuntu
    /opt/muelli/qemu/bin/qemu-system-x86_64 -enable-kvm -hda ubuntu.img -cdrom ~/ISOs/ubuntu-10.04.1-desktop-amd64.iso -monitor stdio -serial vc -m 1G -loadvm 1
  2. Setup Filter
  3. usb_filter_setup /tmp/filter
    export PYTHONPATH=~/hg/scapy-com/
    python /tmp/filter /tmp/phonet.dump

  4. Attach device
  5. info usbhost
    usb_add host:0421:01c8
    sudo chown muelli /dev/bus/usb/002/004

    usb_del 0.2

  6. Replay
  7. usb_add emul:full:/tmp/filter
    cat /tmp/ &
    cat /tmp/phonet.dump.out > /tmp/filter.out

    usb_del 0.0
    kill %%

  8. Fuzz (didn’t really work because of a Heisenbug)
  9. python --relaxed /tmp/filter /tmp/phonet.dump.combined
    python /tmp/filter webcam.dump
    usb_del 0.0

  10. Fully Virtualise

  11. usb_add emul:full:/tmp/filter
    python /tmp/ /tmp/filter.out

mrmcd0x8 – Call for Participation

Die MetaRheinMain ChaosDays gehen in eine neue Runde *yay*! Ich werd’ wohl dieses Jahr nicht koennen, aber ich war ja nun auch schon oft genug dort ;-) Wenn du einen Vortrag oder einen Workshop einreichen willst, benutze bitte das Pentabarf. Ein Grund, etwas einzureichen (oder um einfach nur hinzugehen) ist das Pornophonique Konzert! Wirklich empfehlenswert.

c&p von der offiziellen Seite:

Der CCCMZ, C3F2M, CCC Mannheim, oqlt, der IT Stammtisch Darmstadt und CDA laden zu den achten MetaRheinMain ChaosDays ein.

Die MetaRheinMain Chaosdays 0x8 sind ein jährlich stattfindender Kongress, der dieses Jahr unter dem Motto “Zurueck zum Thema” mit den Themenschwerpunkten Journalismus, Gesellschaft und Technik vom c3f2m Frankfurt, CCCmz (Mainz/Wiesbaden), der Hochschulgruppe Chaos Darmstadt, dem AK Vorrat und weiteren regionalen Gruppen im Rhein-Main-Neckargebiet organisiert wird. Die MRMCDs finden dieses Jahr vom 04.09-06.09.2009 an der Technischen Universität Darmstadt statt. Drei Tage lang werden Vorträge, Diskussionen und ein Hackcenter geboten.

Die Vorträge und Workshops richten sich mit Themen sowohl an die breite Öffentlichkeit, als auch an spezialisierte Interessen. Auf diese Weise soll die wissenschaftliche Anbindung und der Bezug zum aktuellen öffentlichen Diskurs gewahrt werden. Folgende Schwerpunkte bilden das Rückgrat der Veranstaltung:

  • Journalismus
  • Gesellschaft
  • Technik

Darunter fallen z. B.: Wahlmaschinen, Überwachung, Kryptographie, IT-Sicherheit, Biometrie, Vorratsdatenspeicherung, BKA-Gesetz, Elektronische Gesundheitskarte, Auswirkung der Weiterentwicklung von Technik auf die Gesellschaft, Chaos Kultur, Projekt- und Selbstmanagement.