First Android Hacking Event @SSE – A short summary

On 17th of march, we organized our first Android Hacking event. Our participants (a mix of students, security researchers, PhD-students and Post-Docs) had to solve various Android-based challenges on different levels of complexity. Each challenge involved reverse-engineering a specific application without access to the app’s source code – similar to what malware analysts need to accomplish in their daily jobs. Inside these apps, passwords needed to be found, key checking algorithms needed to be understood, and hidden functionality had to be discovered. To accomplish this task, the participants were using different analysis techniques including debugging, decompilation, and fuzzing.

The event was not only great fun for  both the participants and the organizers, but also allowed us to provide free CodeInspect licenses for the day, to be used and tested on the challenges. We were very satisfied with the feedback we got on the tool – we’re making rapid progress towards a stable product. Stay tuned for commercial CodeInspect offerings. In the meantime, our free beta program is still running.

At almost midnight, the winners of the challenges were finally found: Andreas Wittmann, Max Weller and Daniel Magin scored best. Congratulations from the Android team @ SSE.

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New paper on risk estimation factors

The Computers & Security journal, Elsevier, published online, recently, our paper “Incorporating Attacker Capabilities in Risk Estimation and Mitigation“. We propose in this paper the use of attacker capabilities in estimating the risk of threats. Attacker capabilities are the abilities to access system resources that allow to attack the system. We argue that the proposed factor allows the experts to have close risk estimates, which would increase the confidence in risk assessment.

Lambda Expressions Coming to Android?

In Java 8, Oracle added support for Lambda expressions to the Java programming language and the Java Virtual Machine (JVM). Though Android apps are also written in Java, this however doesn’t automatically make them available to app developers. In fact, it takes some time until Android catches up with newer Java developments.

The build chain for Android is (at least at the moment) built on top of the Java build chain: The normal Java compiler takes Java source files and creates Java class files. These files then serve as inputs to Android’s “dx” tool which finally emits the Dalvik bytecode that can be run on an Android device or emulator. In version 19 of the Android build tools, support for Java 1.7 class files was added – with the usual delay (Java 1.7 came out in July 2011, Android build tools v19 came out in April 2012). Up to now, that was the end of the line. But now, Java 1.8 support might be around the corner.

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Google Confirms Tapjacking Attack – Likely All Versions Are Affected!

Stephan Huber and I found a dangerous tapjacking vulnerability in the Android Open Source Project (AOSP) which causes serious security issues. Tapjacking, which is similar to clickjacking for web applications, is an attack where the user clicks/taps on seemingly benign objects in applications, triggering unintended actions not actually intended by the victim[1]. This results to dangerous security issues. Unfortunately, we already found malware samples in the wild that include our attack. To the best of our knowledge, the attack seems to apply to all currently available Android versions back til version 2.3. The attack, together with a patch, has already been submitted to the Android Security team who confirmed our vulnerability and add our patch to the next major release of the AOSP. More details on the attack will follow as soon as the AOSP is patched. The contribution is nominated for Google’s Patch Award.

[1] Marcus Niemietz and Jörg Schwenk, UI Redressing Attacks on Android Devices, BlackHat Asia 2014

Combating Dormant Malware Apps with Harvester

Over the past few days, the news has been full of a report of “dormant” malware that infected millions of Android devices. (German article here on The malware previously went unnoticed by laying dormant for several hours, sometimes multiple days, after installation, in some cases even requiring a reboot of the device to become active. Dynamic-analysis procedures usually only run for minutes and for efficiency reasons do not simulate situations like reboot Contrary to the current perception, though, this problem had long been identified, and in fact today with this article we are revealing Harvester, a new tool to address exactly this problem.

Harvester* uses a unique novel combination of static and dynamic analysis and code transformation to (1) identify and eliminate emulator and timeout checks from apps, and (2) that way allows for the extraction of interesting runtime values such as reflective method calls, target numbers of calls to the SMS APIs, account-data hard-wired in the malware, etc. In addition, Harvester is resilient against virtually all current cases of code obfuscation.

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First International Workshop on Agile Secure Software Development

We are co-organizing the First International Workshop on Agile Secure Software Development (ASSD’15) with Prof. Röning from University of Oulu, Finland. The workshop is organized in conjunction with ARES 2015, which will be hosted in Toulouse, France from 24th to 28th August, 2015. We are looking for papers related to applying the agile approach and methods to develop secure software. We encourage you to submit your paper to the workshop.