Talking at GPN 2018 in Karlsruhe, Germany

Similar to last year I managed to attend the Gulasch Programmier-Nacht (GPN) in Karlsruhe, Germany. Not only did I attend, I also managed to squeeze in a talk about PrivacyScore. We got the prime time slot on the opening day along with all the other relevant talks, including the Eurovision Song Contest, so we were not overly surprised that the audience had a hard time deciding where to go and eventually decided to attend talks which were not recorded. Our talk was recorded and is available here.

Given the tough selection of the audience by the other talks, we had the people who were really interested. And that showed during the official Q&A as well as in the hallway track. We exchanged contacts with other interested parties and got a few excellent comments on the project.

Another excellent part of this year’s GPN was the exhibition in the museum. As GPN takes places in a joint building belonging to the local media university as well as the superb art and media museum, the proximity to the artsy things allows for an interesting combination. This year, the open codes exhibition was not hosted in the ZKM, but GPN also took place in that exhibition. A fantastic setup. Especially with the GPN’s motto being “digital naïves”. One of the exhibition’s pieces is an assembly robot’s hand doing nothing else but writing a manifesto. Much like a disciplinary action for a school child. Except that the robot doesn’t care so much. Yet, it’s usefulness only expands to writing these manifestos. And the robot doesn’t learn anything from it. I like this piece, because it makes me think about the actions we take hoping that they have a desired effect on something or someone but we actually don’t know whether this is indeed the case.

I also like the Critical Engineering Manifesto being exhibited. I like to think about how the people who actual implement cetain technologies can be held responsible for the effects of it on individuals or the society. Especially with more and more “IoT” deployments where the “S” represents their security. It’s easy to blame Facebook for “leaking” user profiles although it’s in their Terms of Services, but it’s harder to shift the blame for the smart milk sensor in your fridge invading my privacy by reporting how much I consume. We will have interesting times ahead of us.

An exhibit pointing out the beauty of algorithms and computation is a board that renders a Julia Set. That’s wouldn’t be so impressive in itself, but you can watch the machine actually compute the values. The exhibit has a user controllable speed regulator and an insight into the CPU as well as the higher level code. I think it’s just an ingenious idea to enable the user to go full speed and see the captivating movements of the beautiful Julia set while also allowing the go super slow to investigate how this beauty is composed of relatively simple operations. Also, the slow execution itself is relatively boring. We get to see that we have to go very fast in order to be entertained. So fast that we cannot really comprehend what is going on.

I whole heartedly recommend visiting this exhibition. And the GPN, of course, too. It’s a nice chaotic event with a particular flair. It’s getting more and more crowded though, so better while the feeling lasts and doesn’t get drowned by all the tourists.

(Almost) talking at the 34C3 in Leipzig, Germany

This season’s CCCongress, the 34C3, (well, the 2017 one) moved from Hamburg to Leipzig. That was planned, in the sense that everybody knew before the event moved to Hamburg, that the location will only be available for a few years.

My own CCCongress experience in the new location is limited, because I could not roam around as much as I wanted to. But I did notice that it was much easier to get lost in Hamburg than in the new venue. I liked getting lost, though.

We had a talk on anonymisation networks (slides, video) scheduled with three people, but my experience with making a show with several people on stage is not so good. So we had a one man show which I think is good enough. Plus, I had private commitments that prevented me from attending the CCCongress as much as I would have wanted to.

I could attend a few talks myself, but I’ll watch most of them later. CCCongress is getting less about the talks but about meeting people you haven’t seen in a while. And it’s great to have such a nice event to cater for the desire to catch up with fellow hackers, exchange ideas and visions.

That said, I’ll happily come back next year, hopefully with a bit more time and preparation to get the most of the visit. Although it hasn’t been announced yet, I would be surprised if it does not take place there again. So you might as well book your accommodation already 😉

Talked at mrmcd 2017 in Darmstadt, Germany

I attended this year’s MRMCD in Darmstadt, Germany. I attended a few times in the past and I think this year’s edition was not as successful as the last ones. The venue changed this year, what probably contributed to some more chaos than usual and hence things not running as smoothly as they did. I assume it will be better next year, when people know how to operate the venue. Although all tickets were sold during the presale phase, it felt smaller than in the last years. In fairness, though, the venue was also bigger this year. The schedule had some interesting talks, but I didn’t really get around to attend many, because I was busy preparing my own shows (yeah, should’ve done that before…).

I had two talks at this conference. The first was on playing the children’s game “battleship” securely (video). That means with cryptography. Lennart and I explained how concepts such as commitment schemes, zero knowledge proofs of knowledge, oblivious transfer, secure multiparty computation and Yao’s protocol can be used to play that game without a trusted third party. The problem, in short, is to a) make sure that the other party’s ships are placed correctly and b) to make sure the other party answers correctly. Of course, if you get hold of the placements of the ships these problems are trivial. But your opponent doesn’t like you to know about the placements. Then a trusted third party would solve that problem trivially. But let’s assume we don’t have such a party. Also, we want to decentralise things, so let’s come up with a solution that involves two players only.

The second problem can be solved with a commitment. A commitment is a statement about a something you’ve chosen but that doesn’t reveal the choice itself nor allows for changing ones mind later. Think of a letter in a closed envelope that you hand over. The receiver doesn’t know what’s written in the letter and the sender cannot change the content anymore. Once the receiver is curious, they can open the envelope. This analogy isn’t the best and I’m sure there’s better real-world concepts to compare to commitment schemes. Anyway, for battleship, you can make the other party commit to the placement of the ships. Then, when the battle starts, you have the other party open the commitment for the field that you’re shooting. You can easily check whether the commitment verifies correctly in order to determine whether you hit a ship or water.

The other problem is the correct placement of the ships, e.g. no ships shall be adjacent, exactly ten ships, exactly one five-field ship, etc. You could easily wait until the end of the game and then check whether everything was placed correctly. But that wouldn’t be (cryptographic) fun. Let’s assume one round of shooting is expensive and you want to make sure to only engage if the other party indeed follows the rules. Now it’s getting a bit crazy, because we need to perform a calculation without learning anything else than “the ships are correctly placed”. That’s a classic zero knowledge problem. And I think it’s best explained with the magic door in a cave.

Even worse, we need to somehow make sure that we cannot change our placement afterwards. There is a brain melting concept of secure multi-party computation which allows you to do exactly that. You can execute a function without knowing what you’re doing. Crazy. I won’t be able to explain how it works in a single blog post and I also don’t intend to, because others are much better in doing that than I could ever be. The gist of the protocol is, that you model your functionality as a Boolean circuit and assign random values to represent “0” or “1” for each wire. You then build the truth table for each gate and replace the values of the table (zeros and ones) with an encryption under both the random value for the first input wire and the random value for the second input wire. The idea now is that the evaluator can only decrypt one value in the truth table given the input keys. There are many more details to care about but eventually you have a series of encrypted, or garbled, gates and you need the relevant keys in order to evaluate it. You can’t tell from the keys you get whether it represents a “0” or a “1”. Hence you can evaluate without knowing the other party’s input.

My other talk was about a probable successor of Return Oriented Programming: Data Oriented Programming (video). In Return Oriented Programming (ROP) and its variants like JOP the aim is to diverge the original control flow in order to make the program execute the attacker’s functionality. This, however, can probably be thwarted by Control Flow Integrity. In its simplest form, it checks on every branch whether it is legit. Think of a database with a list of addresses which are allowed to a list of other addresses. Of course, real-world implementations are more clever. Anyway, let’s assume that we’ll have a hard time exploiting our target with ROP, because we cannot change the CFG of the program. If our attack doesn’t change the CFG, though, we should be safe for anything that detects its modification. That’s the central idea of DOP.

Although I’m not super excited about this year’s edition, I’m looking forward to seeing the next year’s event. I hope it’s going to be a bit more organised; including myself 😉

Talking at GPN 2017 in Karlsruhe, Germany

Although the GPN is an annual event, I haven’t managed to go very often. Last time has already been a while. It’s a pity, because the event is very cute. The location is just amazing which makes being there really fun. It’s a museum hosting many things from our digital world. If you visit only one thing in Karlsruhe, go and visit it. In fact, we tried to organise a small excursion during GUADEC last year. Bloomberg also has an article about the event.

I could only stay one day, but I opened the conference with my talk on building a more secure operating system without sacrificing usability which, of course, was a GNOME related talk. The room was packed and people had to sit on the floor. Based on the feedback I think the people liked to be explained what challenges are to be solved in order to ship more secure systems to more people. You can find the slides here. In case you want to practise your German, you can watch the video here.

The schedule had a few other gems, too. My favourite was Loeschi talking about the upcoming Smart Meter Gateway situation in Germany and how it compares to the rest of Europe. The talk about QR Codes was also nicely done and explained quite well how they work. I hope to be able to attend the event more often 🙂 Especially because I wish the Free Software and the “hacker” people would mingle a bit more.

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 🙂

The Hackocratic Oath

I swear by Eris, Goddess of Chaos, Discordia, and all other Gods above, making them my witnesses, that, according to my ability and judgement, I will keep this Oath and this contract:
To hold those who taught me this art equally dear to me as my friends, to share the Net with them, and to fulfill all their needs for data when required; to look upon their offspring as equals to my own friends, and to teach them this art, if they shall wish to learn it, without fee or contract.
By the set rules, lectures, cat content, and every other mode of instruction, I will impart a knowledge of the art to my own offspring, and those of my friends, and to students bound by this contract and having sworn this Oath to the Hacker Ethic, but to no others.
I will use those data regimens which will benefit my users according to my greatest ability and judgement, and I will do no harm or injustice to them. I will not give a lethal maleware to anyone if I am asked, nor will I advise such a plan; and similarly I will not give a comuter a rootkit.
In purity and according to divine law will I carry out my life and my art.
I will not develop crypto algorithms, but I will leave this to those who are trained in this craft.
Into whatever networks I go, I will enter them for the benefit of the users, avoiding any voluntary act of impropriety or corruption, including hurtful comments towards users or hackers, whether they are online or offline.
Whatever I see or hear in the lives of my patients, whether in connection with my professional practice or by way of leaks, which ought to be private,
I will keep faithfully secret.
So long as I maintain this Oath faithfully and without corruption, may it be granted to me to partake of life fully and the practice of my art, gaining the respect of all for all time. However, should I transgress this Oath and violate it, may the opposite be my fate.
www.mrmcd.net

Talking on Searchable Encryption at 32C3 in Hamburg, Germany

This year again, I attended the Chaos Communication Congress. It’s a fabulous event. It has become much more popular than a couple of years ago. In fact, it’s so popular, that the tickets (probably ~12000, certainly over 9000) have been sold out a week or so after the sales opened. It’s gotten huge.

This year has been different than the years before. Not only were you able to use your educational leave for visiting the CCCongress, but I was also giving a talk. Together with my colleague Christian Forler, we presented on Searchable Encryption. We had the first slot on the last day. I think that’s pretty much the worst slot in the schedule you could get 😉 Not only because the people are in Zombie mode, but also because you have received all those viruses and bacteria yourself. I was lucky enough, but my colleague was indeed sick on day 4. It’s a common thing to be sick after the CCCongress :-/ Anyway, we have hopefully entertained the crowd with what I consider easy slides, compared to the usual™ Crypto talk. We used a lot imagery and tried to allude to funny stuff. I hope people enjoyed it. If you have seen it, don’t forget to leave feedback! It was hard to decide on the appropriate technical level for the almost 1800 people. The feedback we’ve received so far is mixed, so I guess we’ve hit a good spot. The CCCongress was amazingly organised for speakers. They really did care for us and made sure everything was right. So everything was perfect expect for pdfpc which crashed whenever it was meant to display a certain slide… I used Evince then and it worked…

The days at the CCCongress were intense as you might be able to tell from the Fahrplan. It generally started at about 12:00 and ended at about 01:00. And that’s only the talks. You can’t avoid bumping into VIP (very interesting people) and thus spend time in the hallway. And then you have these amazing parties. This year, they had motor-homes and lasers in the dance hall (last year it was a water cannon…). Very crazy atmosphere. It’s highly recommended to spend a night there.

Anyway, day 1 started for me with the Keynote by Fatuma Musa Afrah. The speaker stretched her time a little, I felt. At the beginning I couldn’t really grasp what her topic was or what she wanted to tell us. She repeatedly told us that we had to “kill the time together” which killed my sympathy to some extent. The conference’s motto was Gated Communities. She encouraged us to find ways to open these gates by educating people and helping them. She said that we have to respect each other irrespective of the skin colour or social status. It was only later that she revealed being refugee who came to Germany. Although she told us that it’s “Newcomers”, not “refugees”. In fact, she grew up in Kenya where she herself was a newcomer. She fled to Kenya, so she fled twice. She told us stories about her arriving and living in Germany. I presume she is breaking open the gates which separate the communities she’s living in, but that’s speculation. In a sense she was connecting her refugee community with our hacker community. So the keynote was interesting for that perspective.

Joanna Rutkowska then talked about trustworthy laptops. The basic idea is to have no state on the laptop itself, i.e. no place where malware could be injected. The state should instead be kept on a personal storage medium, like an SD card or a pen drive. She said that laptops are inherently not trustworthy. Trust, she said can be broken up into Trusted, Secure, and Trustworthy. Secure is resistant to attacks. Trusted is something we, as Security community, do not want to have, like a Trusted third party. Trustworthy, she said, is something different, like the Intel Management Engine which might be resistant to attacks, yet it is not acting in the interest of the user. Application level security is meaningless, she said, when we cannot trust the Operating System, because it is the trusted part. If it is compromised then every effort is not useful. Her project, Qubes OS, attempts to reduce the Trusted Computing Base. What is Operating system to the application, is the hardware to the Operating system. The hardware, she said, has been assumed to be trusted. A single malicious peripheral, like a malicious wifi module, can compromise the whole personal computer, the whole digital life, she said. She was referring to problems with Intel x86 platforms. Present Intel processors integrate everything on the main chip. The motherboard has been made more or less only a holder for the CPU and the memory. The construction of those big chips is completely opaque. We have no control over what is inside. And we cannot look inside, even if we wanted to. The firmware is being loaded during boot from a discrete element on the mainboard. We cannot, however, verify what firmware really is on the chip. One question is how to enforce read-only-ness of the system or how to upload your own firmware. For many years, she and others believed that TPM, TXT, or UEFI secure boot could solve that problem. But all of them have shown to fail horribly, she said. Unfortunately, she didn’t mention how so. So as of today, there is no such thing as a secure boot. Inside the processor is a management engine which special, because it is the perfect entry for backdooring and zombification of personal computing. By zombification, she means that the involvement of the Apps (vs. OS vs. Hardware) is decreasing heavily and make the hardware have much more of a say. She said that Intel wants to make the Hardware fully control your computing by having much more logic in the management engine. The ME is, in a sense, a gated community, because you cannot, whatsoever, inspect it, tinker with it, or otherwise get in touch. She said that the war is lost on X86. Even if we didn’t have the management engine. Again, she didn’t say why. Her proposal is to move all those moving firmware parts out to a trusted storage. It was an interesting perspective on what I think is a “simple” Free Software problem. Because we allow proprietary software, we now have the problem to see what is loaded into the hardware. With Free Software we’d still have backdoors in hardware, but assuming that most functionality is encoded in firmware, we could see and modify the existing firmware and build, run, and share our “better” firmware.

Ilja van Sprundel talked about Windows driver security or rather their attack surface. I’m not necessarily interested in Windows per se, but getting some lower level knowledge sounded intriguing. He gave a more high level overview of what to do and what to not do when doing driver development for Windows. The details, he said, matter. For example whether the IOManager probes a buffer in *that* instance. The Windows kernel is made of several managers, he said. The Windows Driver Model (WDM) is the standard model for how drivers are written. The IO Manager proxies requests from user to (WDM drivers. It may or may not validate arguments. Another central piece in the architecture are IO Request Packets (IRPs). They are being delivered from the IO Manager to the driver and contain all the necessary information for the operation in question. He went through the architecture really fast and it was hard for a kernel newbie like me to follow all the concepts he mentioned. Interestingly though, the IO Manager seems to also care about transferring the correct amount of memory from userspace to kernel space (e.g. makes sure data does not overflow) if you want it to using METHOD_BUFFERED. But, as he said, most of the drivers use METHOD_NEITHER which does not check anything at all and is the endless source of driver bugs. It seems as if KMDF is an alternative framework which makes it harder to have bugs. However, you seem to need to understand the old framework in order to use that new one properly. He then went on to talk about the actual attack surface of drivers. The bugs are either privilege escalation, denial of service, or information leak. He said that you could avoid the problem of integer overflow by using the intsafe library. But you have to use them properly! Most importantly, you need to check their return type and use the actual values you want to have been made safe. During creation of a device, a driver can call either IoCreateDeviceSecure with an SDDL string or use an INF file to ACL the device. That is, however, done either rarely or wrongly, he said. You need to think about who needs to have access to your device. When you work with the IOManager, you need to check whether Irp->MdlAddress is NULL which can happen, he said, if it’s a zero sized buffer. Similarly, when using the safer METHOD_BUFFERED mentioned earlier, Irp->AssociatedIrp.SystemBuffer can also be NULL. So avoid having that false sense of security when using that safe API. Another area of bugs is the cancellation of IRPs. The userland can cancel requests which apparently is not handled gracefully by drivers and leads to deadlocks, memory leaks, race conditions, double frees, and other classes of bugs. When dealing with data from userland, you are supposed to “probe” the memory which is basically checking whether the pointers are valid and in the expected range. If you don’t do that, it’ll lead to you writing to arbitrary kernel memory. If you do validate the data from userspace, make sure you don’t fetch it again from user space assuming that it hasn’t changed. There might be race between your check and your usage (TOCTOU). So better capture, validate, and use the data. The same applies when using MDLs. That, however, is more tricky, because you have a double mapping and you are using a kernel pointer. So it is very subtle. When you do memory allocation you can either use ExAllocatePool or ExAllocatePoolWithQuota. The latter throws an exception instead of returning NULL. Your exception or NULL pointer handling needs to be double checked, he said. It was a very technical talk on Windows which was way out of my comfort zone. I only understood a tiny fraction of what he was presenting. But I liked it for the new insight on Windows drivers and that the same old classes of bug have not died yet.

High up on my list of awaited talks was the talk on train systems by the SCADA strangelove people. Railways, he said, is the biggest system built by mankind. It’s main components are signals and switches. Old switches are operated manually by pure force. Modern switches are interlocked with signals such that the signals display forbidden entry when switches are set in certain positions. On tracks, he said, signals are transmitted over the actual track by supplying them with AC or DC. The locomotive picks up the signals and supplies various systems with them. The Eurostar, they said, has about seven security systems on board, among them a “RPS”, a Reactor Protection System which alludes to nuclear trains… They said that lately the “Bahn Automatisierungssystem (SIBAS)” has been updated to use much more modern and less proprietary soft- and hardware such as VxWorks and x86 with ELF binaries as well as XML over HTTP or SS7. In the threat model they identified, they see several attack vectors. Among them are making someone plug a malicious USB device in controlling machines in some operation center. He showed pictures from supposedly real operation centers. The physical security, he said, is terrible. With close to no access control. In one photograph, he showed a screenshot from a documentary aired on TV which showed credentials sticking on the screen… Even if the security is quite good, like good physical security and formally proven programs, it’s still humans who write the software, he said, so there will be bugs to be exploited. For example, he showed screenshots of when he typed “railway” into Shodan and the result included a good number of railway stations. Another vector is GSM-R. If you jam the train’s GSM-R connection, the train will simply stop. Also, you might be able to inject SIM toolkit malware. Via that vector, you might make the modem identify as, e.g. a keyboard and then penetrate further into the systems. Overall an entertaining talk, but the claims were a bit over the top. So no real train hacking just yet.

The talk on memory corruption by Mathias Payer started off by saying that software is unsafe and insecure. Low level languages trade type safety and memory safety for performance. A large set of legacy applications, he said, are prone to memory vulnerabilities. There are, he continued too many bugs to find and fix manually. So we need a runtime system to ensure security. An invalid dereference or an out of bounds pointer is the core of memory unsafety problems. But according to the C language, he claimed, it’s only a violation if the invalid pointer is read, written to, or freed. So during runtime, there are tons and tons of dangling pointers which is perfectly fine. With such a vulnerability a control-flow attack could be executed. Several defenses exist: Data Execution Prevention prevents code from actually being executed. Address Space Layout Randomisation scrambles the memory locations of executable code which makes it harder to successfully exploit a vulnerable. Stack canaries are special values which are supposed to detect overflowing writes. Safe exception handlers ensure that exception code paths follow predefined patterns. The DEP can only work together with ASLR, he said. If you broke ASLR, you could re-use existing code; as it turns out, people do break ASLR every now and then. Two new mechanisms are Stack Integrity and Code Flow Integrity. Stack Integrity enforces to return to the actual caller by having a shadow stack. He didn’t mention how that actually works, though. I suppose you obtain a more secret stack address somewhere and switch the stack pointer before returning to check whether the return address is still correct. Control Flow Integrity builds a control flow graph during compilation and for every control flow change it checks at run time whether the target address is allowed. Apparently, many CFI implementations exist (eleven were shown). He said they’ve measured those and IFCC and Lockdown performed rather badly. To show how all of the protection mechanisms fail, he presented printf-oriented programming. He said that printf was Turing complete and presented a domain specific language. They have built a brainfuck interpreter with snprintf calls. Another rather technical talk by a good speaker. I remember that I was already impressed last year when he presented on these new defense mechanisms.

DJB and Tanja Lange started their “late night show” by bashing TLS as a “gigantic clusterfuck”. They were presenting on quantum computing and cryptography. They started by mentioning that the D-Wave quantum computer exists, but it’s not useful, he said. It doesn’t do the basic things, and can only do limited computations. It can especially not perform Shor’s algorithm. So there’s no “Shor monster coming”. They recommended the Timeline of Quantum Computing as a good reference of the massive research effort going into quantum computing. If there was a general quantum computer pretty much every public key scheme deployed on the Internet today will be broken. But also symmetric schemes are under attack due to Grover’s algorithm which speeds up brute force algorithms significantly. The solution could be physical crypto like using strong (physical) locks. But, he said, the assumptions of those systems are already broken. While Quantum Key Distribution is secure under certain assumptions, those assumptions are off, he said. Secure schemes that survive the quantum era were the topic of their talk. The first workshop on that workshop happened in 2006 and efforts are still being made, e.g. with EU projects on the topic. The time it takes for a crypto scheme to gain significant traction has been long, so far. They gave ECC as an example. It has been introduced in the 1980s, but it’s only now that it’s taking over the deployed crypto on the Internet. So the time it takes is long. They gave recommendations on what to do to have connections that are secure “for at least the next hundred years”. These include at least 256 bit keys for symmetric encryption. McEliece with binary Goppa codes n=6960 k=5413 t=119. An efficient implementation of such a code based scheme is McBits, she said. Hash based signatures with, e.g. XMSS or SPHINCS-256. All you need for those is a proper hash function. The stuff they recommend for the next 100 years, like the McEliece system, are things from the distant past, she said. He said that Post Quantum Cryptography will be the standard in a couple of years from now so he urged the cryptographers in the audience to “get used to this stuff”.

Next on my list was Markus’ talk on Landesverrat which is the incident of Netzpolitik.org being investigated for revealing secret documents. He referred on the history of the case, how it came around that they were suspected of revealing secret documents. He said that one of their believes is to publish their sources, even the secret ones. They want their work to be critically reviewed and they believe that it is only possible if the readers can inspect the sources. The documents which lead to the criminal investigations were about finances of the introduction of the XKeyscore software. Then, the president of the “state security” filed a case against because of revealing secret documents. They wanted to publish the investigation files, but they couldn’t see them, because they were considered to be more secret than the documents they have already published… From now on, he said, they are prepared for the police raiding their offices, which I suppose is good standard preparation. They were lucky, he said, because their case fell into the regular summer low of news which could make the case become quite popular in the media. A few weeks earlier or later and they were much less popular due to the refugees or Greece. During the press coverage, they had a second battleground where they threw out a Russian television team who entered their offices without having called or otherwise introduced themselves… For the future, he wants to see changes in what is considered to be a state secret. He doesn’t want the government to decide what such a secret is. He also wants to have much more protection for whistle blowers. Freedom of press should also hold for people who do not blog for their “occupation”, but also hobbyists.

Vincent Haupert was then talking on App-based TAN online banking methods. It’s a classic two factor method: Not only username and password, but also a TAN. These TAN methods have since evolved in various ways. He went on to explain the general online banking process: You log in with your credentials, you create a new wire transfer and are then asked to provide a TAN. While ChipTAN would solve many problems, he said, the banking industry seems to want their customers to be able to transfer money everywhere™. So you get to have two “Apps” on your mobile computer. The banking app and a TAN app. However, malware in “official” app stores are a reality, he said. The Google Playstore cannot protect against malware, as a colleague of him demonstrated during his bachelor thesis. This could also been by the “Brain Test” app which roots your device and then loads malware. Anyway, they hijacked the connection from the banking app to modify the recipient of the issued wire transfer and the TAN being pushed on the device. They looked at the apps and found that they “protected” their app with “Promon Shield“. That seems to be a strong obfuscation framework. Their attack involved tricking the root and hooks detection. For the root detection they check on the file system for certain binaries. He could simply change the filenames and was good to go. For the hooks (Xposed) it was pretty much the same with the exception of a few filenames which needed more work. With these modifications they could also “hack” the newer version 1.0.7. Essentially the biggest part of the problem is that the two factors are on one device. If the attacker hijacks that one device then ,

The talk by Christian Schaffner on Quantum Cryptography was introducing the audience to quantum mechanics. He said that a qubit can be imagined as the direction of a polarised photon. If you make the direction of the photons either horizontal or vertical, you can imagine that as representing 0 or 1. He was showing an actual physical experiment with a laser pointer and polarisation filters showing how the red dot of the laser pointer is either filtered or very visible. He also showed how actually measuring the polarisation changes the state of the photons! So yet another filter made the point in the back brighter. That was a bit weird, but that’s quantum mechanics. He showed a quantum random number generator based on that technology. One important concept is the no-cloning theorem which state that you can make a perfect copy of a quantum bit. He also compared current and “post quantum” crypto systems against efficient classical attackers and efficient quantum attackers. AES, SHA, RSA (or discrete logs) will be broken by quantum attacks. Hash-based signatures, McEliece, and lattice-based cryptography he considered to be resistant against quantum based attacks. He also mentioned that Quantum Key Distribution systems will also be against an exhaustive attacker who applies brute force. QKD is based on the no-cloning theorem so an eavesdropper cannot see the same bits as the communicating parties do. Finally, he asked how you could prove that you have been at a certain location to avoid the pizza delivery problem (i.e. to be certain about the place of delivery).

Fefe was talking on privileges. He said that software will be vulnerable. Various techniques should be applied such as simply fixing all the bugs (haha…) or make exploitation harder by applying ASLR or ROP protection. Another idea is to put the program in a straight jacket and withdraw privileges. That sounds a lot like containerisation. Firstly, you can drop your privileges from superuser down to the least privileges you need, then do privilege separation. Another technique is the admin confining the app in a jail instead of the app confining itself. Also, you can implement access control via a broker service by splitting up your process into, say, a left half which opens and reads files and a right half which processes data. When doing privilege separation, the idea is to split up the process into several separately running programs. Jailing is like firewall rules for syscalls which, he said, is impossible for complex programs. He gave Firefox as an example of it being impossible to write a rule set for. The app containing itself is like a werewolf chaining itself to the wall before midnight, he said. You restrict yourself from opening files, creating socket, or from attaching yourself as a debugger to other processes. The broker service is probably like a reference monitor. He went on showing how old-school privilege dropping works. You could do it as easily as seteuid(getuid()), but that’s not enough, because there is the saved UID, so you need to setresuid and not forget to check the return code. Because the call can fail if, for example, the target UID had already been running too many processes for its quota. He said that you should fail the build if your target platform does not provide setresuid. However, dropping privileges is more than setting your UID. It’s also about freeing resources you don’t necessarily need. Common approaches to jailing your process are to have a fake filesystem with only the necessary files, so your process cannot ever access anything that it shouldn’t. On Linux, that would probably be chroot. However, you can escape using fchdir . Also, mounting your /proc into the chroot, information about the host is exposed. So you need to do more work than calling chroot. The BSDs, he said, have Securelevel which is a kernel mode that only increases which withdraws certain privileges. They also have jails which is a chroot on steroids, he said. It leaks some information due the PIDs, though, he said.

The next talk was on Shellphish, an automatic exploitation framework. This is really fascinating stuff. It’s been used for various Capture the Flag contests which are basically about hacking other teams’ software services. In fact, the presenters were coming from the UCSB which is hosting the famous iCtF. They went from solving security challenges to developing a system which solves security challenges. From a vulnerability binary, they (automatically) develop an exploit and a patched binary which is immune to the exploit, but preserves the functionality of the program. They automatically find vulnerabilities, patches, and test both the exploits and the patches. For the automated vulnerability component, they presented Angr. It has a symbolic execution engine looking for memory accesses outside allocated regions and unconstrained instruction pointer which is a jump controlled by user input (JMP eax). They have written a paper for NDSS about “Augmenting Fuzzing Through Selective Symbolic Execution“. Angr is a Python library and they showed how to use it for identifying the overhyped Back to 28 vulnerability. Actually, there is too much state for a regular symbolic executor to find this problem. Angr does “veritesting“. He showed that his Angr script found the vulnerability by him having excluded many paths of execution that don’t really generate new state with a few lines of code. He didn’t show though what the lines of code were and how he determined how the states are not adding any new information.

The next talk was given by the people behind Intelexit was about convincing NSA agents to stop their work and serve democracy instead. They rented a van with big mottoes printed on them, like “Listen to your heart, not to private phone calls”. They also stuck the constitution on the “constitution protection office” which then got torn apart. Another action they did was to fly over the dagger complex and to release flyers about leaving the secret services. They want to have a foundation helping secret service agents to leave their job or to blow the whistle. They also want an anonymous call service where agents can call to talk about their job. I recommend browsing their photos.

Another artsy talk was on a cheap Facebook army. Actually it was on Instagram followers. The presenter is an artist himself and he’d buy Instagram followers for fellow artists “to make them all equal”. He dislikes the fact that society seems to measure the value or quality of art in followers or likes on social media.

Around the CCCongress were also other artsy installations like this one called “machine learning”:

It’s been a fabulous event. I really admire the people organising this event each and every year. Thank you so much and see you next year, hopefully.

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 window.name. 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 😉

GPN 2014 in Karlsruhe

The Gulash Programmier Nacht (GPN) took place in Karlsruhe, Germany. The local subsidiary of the Chaos Computer Club organised that event, which apparently took place for the 14th time. So far, I wasn’t able to attend, but this time I made it.

It’s a 200 to 300 people event, focussed at hacking, making, and talks around that. It’s very cosy and somewhat similar to the mrmcds. Most of the talks were held in German, a few in English, but I think that could easily change if there is a demand.

The conference was keynoted by tante, who talked about the political aspects of code and the responsibility every developer has. It was good to hear someone saying that you do create reality for people with the software you write and that you are indeed responsible for the view on the world the users of your software have. There were a few other interesting thoughts and I think I agree with the results of the analysis conducted to a great extent. But I think a few areas are not well covered. For example, he said that you limit the people with your software. I don’t think that’s necessarily true. If you provide your users with enough freedoms, i.e. by choosing a Free Software license, than I don’t think his argument is valid anymore.

On the more funny side, a chemist taught us about chemistry based on the stories of Walter White. It was a funny talk with many interludes of the TV series. She explained what the people in the episodes were doing and how close that is to reality. Turns out, it is quite close and at least stupid mistakes were not done.

We also learned about Perl 6. If you think Perl is ugly, he said, it’s not modern Perl. The new and shiny Perl 6 allows you to write short code while looking nice, he said. He showed some features that make it easy to write command line tools. You can simply declare an argument to your main function and Perl would expose that to the user, e.g. by presenting a help screen. It would also detect the types provided and do some magic fancy stuff like checking whether the provided argument is an existing (or empty) file.

A very interesting talk was given on the Enigma, the German crypto machine. He showed the machine that broke the crypto and now stands in Bletchley Park. He told stories about the development and operation of that machine. Very interesting indeed. Also well done on a technical level, the slides were really well done.

I was invited to give talk on GNOME. As you can see in the video, my battery didn’t even last the full 90 minutes slot I was assigned. Something is certainly wrong, either this Linux thing or my battery. Anyway, the talk itself went very well, and it was particularly well attended for that early slot. I was also positively surprised by the audience asking many questions and while I specifically asked for flames, I didn’t get that many.

(Late) report on 30C3

Oh, I almost missed to report on this year’s CCCongress, 30C3. The thirtieths CCCongress. It has grown considerably over the last few years. We’ve reached over 9000 visitors whereas we had 4000 a couple of years ago. The new venue in Hamburg is amazing. Despite the impressive number of attendees, it didn’t feel crowded at all. So many nice details made the venue just awesome. It really felt like it was *the* place to be. A rather big detail was the installation of a letter shoot. Yes, a real pneumatic postal delivery system. With routing and all. Just amazing.

That’s pretty much all I have to say. It was, of course, nice to meet so many old friends and people. I couldn’t even say hi to all of the ones I wanted to meet. What follows is a bit of a rundown of some of the talks that I’ve actually seen, hoping you can evaluate whether you want to see any of that yourself.

I was a bit late for the conference, probably one of the first talks I’ve seen was DJB on, guess what, crypto. It even has a reference to Poettering (who I was also able to meet 🙂 )!

Funnily enough, Nate from the EFF mentioned DJB in his talk on disclosure Dos and Donts. He said that it would be smart to think about how much fuzz one wants to make about a vulnerability at hand. Sure enough, the title needs to be catchy enough for people to notice. If you were DJB, then the lecture hall would be filled even if the title was “DJB has something to say”.

Something that stirred up the community was
Assange’s talk. Apparently sabotaged, the Skype connection wasn’t all too good. But it was also not very interesting. The gist: Sysadmin: Go to the three-letter-agencies and carry out document to become the next Snowden. Good advice.

As for carried out documents, Jake Applebaum presented the NSA’s shopping cart which includes all sorts of scary techniques and technologies. If you have only time to watch one video, make it this one. That’s probably even safer than sitting in the audience. Just after he showed the reconnaissance tools for the investigators to combine various data sources, undoubtedly including cell phone location and people around you, he switched on his cell phone so that the audience would have a connection with him. The one who knows he is being spied on. It was a very emotional talk, too.

Another depressing thing was Jöran talking about the missed (digital) opportunities in education. The most noticeable thing he said was that Apple products are consuming devices only. But the reality is that they make it work 93% of the time as opposed to 90%. But that difference makes teachers use it…

More scary, was the presentation on exploration and exploitation SD card controllers. You’re basically screwed. You have close to no idea what it running on the micro controller on your SD card. And on the various other controllers you carry around. They got themselves access to the chip and were able to flash their own firmware. Doesn’t sound all too exciting, but it is an eye opener that your stupid almost invisible SD card can spy on you.

A strange talk was the one on Digital Bank robberies. There are so many weird details they talk about. They claim to have been called for investigation of a malware that found on ATMs in Brazil. The weirdest thing for me was that the physical damage done to the ATMs went unnoticed. The gangsters needed to install a pendrive so they had to break the case. Which apparently isn’t all too secure. And then they had to make the ATM reboot to boot off the pendrive. Without having to press a key. It is unclear to me whether they could leave the pendrive or not. Apparently they could remove it, because if they couldn’t then the malware could have been found much earlier. But given that the ATMs reboot so easily, it would make sense to install the malware on the ATMs hard drive. In that case they could have spotted the malware rather easily. Anyway, the presenting people were not Brazilian. Why would such a sensitive Brazilian investigation be undertaken by foreigners?

Another interesting, although weirdly presented, talk on X Security was given by Ilja van Sprundel. He looked at X code and identified a good number of easily exploitable bugs. No wonder given that the code is 30 years old… He also mentioned libraries on top of X such as GTK+ or Qt and explained how the security story from GNOME was very different from Qt’s. Essentially: The GNOME guys understood security. Qt didn’t.

On the more fun side, the guys from Ztohoven presented their recent work. They are probably best known for their manipulated video which ran during morning TV shows (IIRC).

In their presentation they talked about their performance for which they obtained numbers from parliamentarians and sent them text messages during a session that was aired live. Quite funny, actually. And the technical details are also interesting.

Another artsy piece is “Do You Think That’s Funny?” (program link) in which the speaker describes the troubles their artistic group had to go through during or after their performances. They did things like vote auction (WP), Alanohof, or AnuScan, and their intention is to make surveillance visible and show how it makes activists censor themselves.

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This work by Muelli is licensed under a Creative Commons Attribution-ShareAlike 3.0 Unported.