Code obfuscation is a popular approach to turn program comprehension and analysis harder, with the aim of mitigating threats related to malicious reverse engineering and code tampering. However, programming languages that compile to high level bytecode (e.g., Java) can be obfuscated only to a limited extent. In fact, high level bytecode still contains high level relevant information that an attacker might exploit. In order to enable more resilient obfuscations, part of these programs might be implemented with programming languages (e.g., C) that compile to low level machine-dependent code. In fact, machine code contains and leaks less high level information and it enables more resilient obfuscations. In this paper, we present an approach to automatically translate critical sections of high level Java bytecode to C code, so that more effective obfuscations can be resorted to. Moreover, a developer can still work with a single programming language, i.e., Java.
This attack is possible, because the application itself is not dependent to the specific OVM. As a countermeasure, techniques have been proposed to inject such bindings @cite_16 .
@cite_16
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In this paper, we present a model for application distribution and related security attacks in dense vehicular ad hoc networks (VANET) and sparse VANET which forms a delay tolerant network (DTN). We study the vulnerabilities of VANET to evaluate the attack scenarios and introduce a new attacker‘s model as an extension to the work done in [6]. Then a VANET model has been proposed that supports the application distribution through proxy app stores on top of mobile platforms installed in vehicles. The steps of application distribution have been studied in detail. We have identified key attacks (e.g. malware, spamming and phishing, software attack and threat to location privacy) for dense VANET and two attack scenarios for sparse VANET. It has been shown that attacks can be launched by distributing malicious applications and injecting malicious codes to On Board Unit (OBU) by exploiting OBU software security holes. Consequences of such security attacks have been described. Finally, countermeasures including the concepts of sandbox have also been presented in depth. In this paper we present software countermeasures specifically designed to counteract fault injection attacks during the execution of a software implementation of a cryptographic algorithm and analyze the efficiency of these countermeasures. We propose two approaches based on the insertion of redundant computations and checks, which in their general form are suitable for any cryptographic algorithm. In particular, we focus on selective instruction duplication to detect single errors, instruction triplication to support error correction, and parity checking to detect corruption of a stored value. We developed a framework to automatically add the desired countermeasure, and we support the possibility to apply the selected redundancy to either all the instructions of the cryptographic routine or restrict it to the most sensitive ones, such as table lookups and key fetching. Considering an ARM processor as a target platform and AES as a target algorithm, we evaluate the overhead of the proposed countermeasures while keeping the robustness of the implementation high enough to thwart most or all of the known fault attacks. Experimental results show that in the considered architecture, the solution with the smallest overhead is per-instruction selective doubling and checking, and that the instruction triplication scheme is a viable alternative if very high levels of injected fault resistance are required. Row hammer attacks exploit electrical interactions between neighboring memory cells in high-density dynamic random-access memory (DRAM) to induce memory errors. By rapidly and repeatedly accessing DRAMs with specific patterns, an adversary with limited privilege on the target machine may trigger bit flips in memory regions that he has no permission to access directly. In this paper, we explore row hammer attacks in cross-VM settings, in which a malicious VM exploits bit flips induced by row hammer attacks to crack memory isolation enforced by virtualization. To do so with high fidelity, we develop novel techniques to determine the physical address mapping in DRAMmodules at runtime (to improve the effectiveness of double-sided row hammer attacks), methods to exhaustively hammer a large fraction of physical memory from a guest VM (to collect exploitable vulnerable bits), and innovative approaches to break Xen paravirtualized memory isolation (to access arbitrary physical memory of the shared machine). Our study also suggests that the demonstrated row hammer attacks are applicable in modern public clouds where Xen paravirtualization technology is adopted. This shows that the presented cross-VM row hammer attacks are of practical importance. We describe several software side-channel attacks based on inter-process leakage through the state of the CPU’s memory cache. This leakage reveals memory access patterns, which can be used for cryptanalysis of cryptographic primitives that employ data-dependent table lookups. The attacks allow an unprivileged process to attack other processes running in parallel on the same processor, despite partitioning methods such as memory protection, sandboxing, and virtualization. Some of our methods require only the ability to trigger services that perform encryption or MAC using the unknown key, such as encrypted disk partitions or secure network links. Moreover, we demonstrate an extremely strong type of attack, which requires knowledge of neither the specific plaintexts nor ciphertexts and works by merely monitoring the effect of the cryptographic process on the cache. We discuss in detail several attacks on AES and experimentally demonstrate their applicability to real systems, such as OpenSSL and Linux’s dm-crypt encrypted partitions (in the latter case, the full key was recovered after just 800 writes to the partition, taking 65 milliseconds). Finally, we discuss a variety of countermeasures which can be used to mitigate such attacks.