No abstract

Automated software testing based on fuzzing has experienced a revival in recent years. Especially feedback-driven fuzzing has become well-known for its ability to efficiently perform randomized testing with limited input corpora. Despite a lot of progress, two common problems are magic numbers and (nested) checksums. Computationally expensive methods such as taint tracking and symbolic execution are typically used to overcome such roadblocks. Unfortunately, such methods often require access to source code, a rather precise description of the environment (e.g., behavior of library calls or the underlying OS), or the exact semantics of the platform's instruction set. In this paper, we introduce a lightweight, yet very effective alternative to taint tracking and symbolic execution to facilitate and optimize state-of-the-art feedback fuzzing that easily scales to large binary applications and unknown environments. We observe that during the execution of a given program, parts of the input often end up directly (i.e., nearly unmodified) in the program state. This input-to-state correspondence can be exploited to create a robust method to overcome common fuzzing roadblocks in a highly effective and efficient manner. Our prototype implementation, called REDQUEEN, is able to solve magic bytes and (nested) checksum tests automatically for a given binary executable. Additionally, we show that our techniques outperform various state-of-the-art tools on a wide variety of targets across different privilege levels (kernel-space and userland) with no platform-specific code. REDQUEEN is the first method to find more than 100% of the bugs planted in LAVA-M across all targets. Furthermore, we were able to discover 65 new bugs and obtained 16 CVEs in multiple programs and OS kernel drivers. Finally, our evaluation demonstrates that REDQUEEN is fast, widely applicable and outperforms concurrent approaches by up to three orders of magnitude.

The European Union's General Data Protection Regulation (GDPR) went into effect on May 25, 2018. Its privacy regulations apply to any service and company collecting or processing personal data in Europe. Many companies had to adjust their data handling processes, consent forms, and privacy policies to comply with the GDPR's transparency requirements. We monitored this rare event by analyzing changes on popular websites in all 28 member states of the European Union. For each country, we periodically examined its 500 most popular websites -6,579 in total -for the presence of and updates to their privacy policy between December 2017 and October 2018. While many websites already had privacy policies, we find that in some countries up to 15.7 % of websites added new privacy policies by May 25, 2018, resulting in 84.5 % of websites having privacy policies. 72.6 % of websites with existing privacy policies updated them close to the date. After May this positive development slowed down noticeably. Most visibly, 62.1 % of websites in Europe now display cookie consent notices, 16 % more than in January 2018. These notices inform users about a site's cookie use and user tracking practices. We categorized all observed cookie consent notices and evaluated 28 common implementations with respect to their technical realization of cookie consent. Our analysis shows that core web security mechanisms such as the same-origin policy pose problems for the implementation of consent according to GDPR rules, and opting out of third-party cookies requires the third party to cooperate. Overall, we conclude that the web became more transparent at the time GDPR came into force, but there is still a lack of both functional and usable mechanisms for users to consent to or deny processing of their personal data on the Internet.

Abstract:With the general availability of closed-source software for various CPU architectures, there is a need to identify security-critical vulnerabilities at the binary level. Unfortunately, existing bug finding methods fall short in that they i) require source code, ii) only work on a single architecture (typically x86), or iii) rely on dynamic analysis, which is difficult for embedded devices. In this paper, we propose a system to derive bug signatures for known bugs. First, we compute semantic hashes for the basic blocks of the binary. When can then use these semantics to find code parts in the binary that behave similarly to the bug signature, effectively revealing code parts that contain the bug. As a result, we can find vulnerabilities, e.g., the famous Heartbleed vulnerabilities, in buggy binary code for any of the supported architectures (currently, ARM, MIPS and x86).

Voice interfaces are becoming accepted widely as input methods for a diverse set of devices. This development is driven by rapid improvements in automatic speech recognition (ASR), which now performs on par with human listening in many tasks. These improvements base on an ongoing evolution of deep neural networks (DNNs) as the computational core of ASR. However, recent research results show that DNNs are vulnerable to adversarial perturbations, which allow attackers to force the transcription into a malicious output.In this paper, we introduce a new type of adversarial examples based on psychoacoustic hiding. Our attack exploits the characteristics of DNN-based ASR systems, where we extend the original analysis procedure by an additional backpropagation step. We use this backpropagation to learn the degrees of freedom for the adversarial perturbation of the input signal, i.e., we apply a psychoacoustic model and manipulate the acoustic signal below the thresholds of human perception. To further minimize the perceptibility of the perturbations, we use forced alignment to find the best fitting temporal alignment between the original audio sample and the malicious target transcription. These extensions allow us to embed an arbitrary audio input with a malicious voice command that is then transcribed by the ASR system, with the audio signal remaining barely distinguishable from the original signal. In an experimental evaluation, we attack the state-of-the-art speech recognition system Kaldi and determine the best performing parameter and analysis setup for different types of input. Our results show that we are successful in up to 98 % of cases with a computational effort of fewer than two minutes for a ten-second audio file. Based on user studies, we found that none of our target transcriptions were audible to human listeners, who still understand the original speech content with unchanged accuracy.

Long Term Evolution (LTE) is the latest mobile communication standard and has a pivotal role in our information society: LTE combines performance goals with modern security mechanisms and serves casual use cases as well as critical infrastructure and public safety communications. Both scenarios are demanding towards a resilient and secure specification and implementation of LTE, as outages and open attack vectors potentially lead to severe risks. Previous work on LTE protocol security identified crucial attack vectors for both the physical (layer one) and network (layer three) layers. Data link layer (layer two) protocols, however, remain a blind spot in existing LTE security research.In this paper, we present a comprehensive layer two security analysis and identify three attack vectors. These attacks impair the confidentiality and/or privacy of LTE communication. More specifically, we first present a passive identity mapping attack that matches volatile radio identities to longer lasting network identities, enabling us to identify users within a cell and serving as a stepping stone for follow-up attacks. Second, we demonstrate how a passive attacker can abuse the resource allocation as a side channel to perform website fingerprinting that enables the attacker to learn the websites a user accessed. Finally, we present the ALTER attack that exploits the fact that LTE user data is encrypted in counter mode (AES-CTR) but not integrity protected, which allows us to modify the message payload. As a proof-of-concept demonstration, we show how an active attacker can redirect DNS requests and then perform a DNS spoofing attack. As a result, the user is redirected to a malicious website. Our experimental analysis demonstrates the real-world applicability of all three attacks and emphasizes the threat of open attack vectors on LTE layer two protocols.

Zusammenfassung. Denial-of-Service (DoS) attacks pose a significant threat to the Internet today especially if they are distributed, i.e., launched simultaneously at a large number of systems. Reactive techniques that try to detect such an attack and throttle down malicious traffic prevail today but usually require an additional infrastructure to be really effective. In this paper we show that preventive mechanisms can be as effective with much less effort: We present an approach to (distributed) DoS attack prevention that is based on the observation that coordinated automated activity by many hosts needs a mechanism to remotely control them. To prevent such attacks, it is therefore possible to identify, infiltrate and analyze this remote control mechanism and to stop it in an automated fashion. We show that this method can be realized in the Internet by describing how we infiltrated and tracked IRC-based botnets which are the main DoS technology used by attackers today.

Fuzz testing is a well-known method for efficiently identifying bugs in programs. Unfortunately, when programs that require highly-structured inputs such as interpreters are fuzzed, many fuzzing methods struggle to pass the syntax checks: interpreters often process inputs in multiple stages, first syntactic and then semantic correctness is checked. Only if both checks are passed, the interpreted code gets executed. This prevents fuzzers from executing "deeper"-and hence potentially more interesting-code. Typically, two valid inputs that lead to the execution of different features in the target program require too many mutations for simple mutation-based fuzzers to discover: making small changes like bit flips usually only leads to the execution of error paths in the parsing engine. So-called grammar fuzzers are able to pass the syntax checks by using Context-Free Grammars. Feedback can significantly increase the efficiency of fuzzing engines and is commonly used in state-of-the-art mutational fuzzers which do not use grammars. Yet, current grammar fuzzers do not make use of code coverage, i.e., they do not know whether any input triggers new functionality. In this paper, we propose NAUTILUS, a method to efficiently fuzz programs that require highly-structured inputs by combining the use of grammars with the use of code coverage feedback. This allows us to recombine aspects of interesting inputs, and to increase the probability that any generated input will be syntactically and semantically correct. We implemented a proofof-concept fuzzer that we tested on multiple targets, including ChakraCore (the JavaScript engine of Microsoft Edge), PHP, mruby, and Lua. NAUTILUS identified multiple bugs in all of the targets: Seven in mruby, three in PHP, two in ChakraCore, and one in Lua. Reporting these bugs was awarded with a sum of 2600 USD and 6 CVEs were assigned. Our experiments show that combining context-free grammars and feedback-driven fuzzing significantly outperforms state-of-the-art approaches like AFL by an order of magnitude and grammar fuzzers by more than a factor of two when measuring code coverage. An intuitive solution to this problem is to use (context-free) grammars to generate syntactically-correct inputs. Previous works [5], [17], [36], [47] use this approach, but they do not leverage instrumentation feedback, which allows the fuzzer to distinguish inputs that reach a new part of the code base from inputs that reach no new code. Leveraging feedback led to a great improvement in the performance of general-purpose fuzzers. One of the most popular feedback-oriented fuzzers is AFL [19], which was used to identify bugs in hundreds of applications and tools. Using code coverage feedback, AFL is able to intelligently combine interesting inputs to explore deeper code, which would take an unreasonable amount of time without feedback. In contrast, AFL struggles with heavily-structured file formats since it is optimized for binary formats and does not support grammars. Note that AFL can be provided with a list of...