Biblio

The spread of the Internet of Things (IoT) and the use of smart control systems in many mission-critical or safety-critical applications domains, like automotive or aeronautical, make devices attractive targets for attackers. Nowadays, several of these are mixed-criticality systems, i.e., they run both high-criticality tasks (e.g., a car control system) and low-criticality ones (e.g., infotainment). High-criticality routines often employ Real-Time Operating Systems (RTOS) to enforce hard real-time requirements, while the tasks with lower constraints can be delegated to more generic-purpose operating systems (GPOS).Much of the control code for these devices is written in memory-unsafe languages such as C and C++. This makes them susceptible to powerful binary attacks, such as the famous Return-Oriented Programming (ROP). Control-Flow Integrity (CFI) is the most investigated security technique to protect against such threats. At now, CFI solutions for real-time embedded systems are not as mature as the ones for general-purpose systems, and even more, there is a lack of in-depth studies on how different operating systems with different security requirements and timing constraints can coexist on a single multicore platform.This paper aims at drawing attention to the subject, discussing the current scientific proposal, and in turn proposing a solution for an optimized asymmetric verification system for execution integrity. By using an embedded hypervisor, predefined cores could be dedicated to only high or low-criticality tasks, with the high-priority core being monitored by the lower-criticality core, relying on offline binary instrumentation and a light exchange of information and signals at runtime. The work also presents preliminary results about a possible implementation for multicore ARM platforms, running both RTOS and GPOS, both in terms of security and performance penalties.

Memory-based vulnerabilities are becoming more and more common in low-power and low-cost devices in IOT. We study several low-level vulnerabilities that lead to memory corruption in C and C++ programs, and how to use stack corruption and format string attack to exploit these vulnerabilities. Automatic methods for resisting memory attacks, such as stack canary and address space layout randomization ASLR, are studied. These methods do not need to change the source program. However, a return-oriented programming (ROP) technology can bypass them. Control flow integrity (CFI) can resist the destruction of ROP technology. In fact, the security design is holistic. Finally, we summarize the rules of security coding in embedded devices, and propose two novel methods of software anomaly detection process for IOT devices in the future.

The pervasive presence of smart objects in almost every corner of our everyday life urges the security of such embedded systems to be the point of attention. Memory vulnerabilities in the embedded program code, such as buffer overflow, are the entry point for powerful attack paradigms such as Code-Reuse Attacks (CRAs), in which attackers corrupt systems’ execution flow and maliciously alter their behavior. Control-Flow Integrity (CFI) has been proven to be the most promising approach against such kinds of attacks, and in the literature, a wide range of flow monitors are proposed, both hardware-based and software-based. While the formers are hardly applicable as they impose design alteration of underlying hardware modules, on the contrary, software solutions are more flexible and also portable to the existing devices. Real-Time Operating Systems (RTOS) and their key role in application development for embedded systems is the main concern regarding the application of the CFI solutions.This paper discusses the still open challenges and issues regarding the implementation of control-flow integrity policies on operating systems for embedded systems, analyzing the solutions proposed so far in the literature, highlighting possible limits in terms of performance, applicability, and protection coverage, and proposing possible improvement directions.

Nowadays, exploits often rely on a code-reuse approach. Short pieces of code called gadgets are chained together to execute some payload. Code-reuse attacks can exploit vul-nerabilities in the presence of operating system protection that prohibits data memory execution. The ROP chain construction task is the code generation for the virtual machine defined by an exploited executable. It is crucial to understand how powerful ROP attacks can be. Such knowledge can be used to improve software security. We implement MAJORCA that generates ROP and JOP payloads in an architecture agnostic manner and thoroughly consider restricted symbols such as null bytes that terminate data copying via strcpy. The paper covers the whole code-reuse payloads construction pipeline: cataloging gadgets, chaining them in DAG, scheduling, linearizing to the ready-to-run payload. MAJORCA automatically generates both ROP and JOP payloads for x86 and MIPS. MAJORCA constructs payloads respecting restricted symbols both in gadget addresses and data. We evaluate MAJORCA performance and accuracy with rop-benchmark and compare it with open-source compilers. We show that MAJORCA outperforms open-source tools. We propose a ROP chaining metric and use it to estimate the probabilities of successful ROP chaining for different operating systems with MAJORCA as well as other ROP compilers to show that ROP chaining is still feasible. This metric can estimate the efficiency of OS defences.

Intel SGX provides a new method to protect software privacy data, but it faces the security risk of side channel attack. In our opinion, SGX side channel attack depend on the implicit mapping between control flow and data flow to infer privacy data indirectly with control flow. For this reason, we propose code reuse to construct dynamic control flow software. In this method, by loading a large number of related gadgets in advance, the software reset the software control data according to the original software semantics at runtime, so that the software control flow can change dynamically heavily. Based on code reuse, we make the software control flow change dynamically, and the mapping between control flow and data flow more complex and difficult to determine, which can increase the difficulty of SGX side channel attack.

Largely known for attack scenarios, code reuse techniques at a closer look reveal properties that are appealing also for program obfuscation. We explore the popular return-oriented programming paradigm under this light, transforming program functions into ROP chains that coexist seamlessly with the surrounding software stack. We show how to build chains that can withstand popular static and dynamic deobfuscation approaches, evaluating the robustness and overheads of the design over common programs. The results suggest a significant amount of computational resources would be required to carry a deobfuscation attack for secret finding and code coverage goals.

Memory corruption vulnerabilities, mainly present in C and C++ applications, may enable attackers to maliciously take control over the program running on a target machine by forcing it to execute an unintended sequence of instructions present in memory. This is the principle of modern Code-Reuse Attacks (CRAs) and of famous attack paradigms as Return-Oriented Programming (ROP) and Jump-Oriented Programming (JOP). Control-Flow Integrity (CFI) is a promising approach to protect against such runtime attacks. Recently, many CFI-based solutions have been proposed, resorting to both hardware and software implementations. However, many of these solutions are hardly applicable to microcontroller systems, often very resource-limited. The paper presents a generic, portable, and lightweight CFI solution for bare-metal embedded systems, i.e., systems that execute firmware directly from their Flash memory, without any Operating System. The proposed defense mixes software and hardware instrumentation and is based on monitoring the Control-Flow Graph (CFG) with an FPGA connected to the CPU. The solution, applicable in principle to any architecture which disposes of an FPGA, forces all control-flow transfers to be compliant with the CFG, and preserves the execution context from possible corruption when entering unpredictable code such as Interrupt Services Routines (ISR).

With the recent proliferation of Internet of Things (IoT) and embedded devices, there is a growing need to develop a security framework to protect such devices. RISC-V is a promising open source architecture that targets low-power embedded devices and SoCs. However, there is a dearth of practical and low-overhead security solutions in the RISC-V architecture. Programs compiled using RISC-V toolchains are still vulnerable to code injection and code reuse attacks such as buffer overflow and return-oriented programming (ROP). In this paper, we propose FIXER, a hardware implemented security extension to RISC-V that provides a defense mechanism against such attacks. FIXER enforces fine-grained control-flow integrity (CFI) of running programs on backward edges (returns) and forward edges (calls) without requiring any architectural modifications to the RISC-V processor core. We implement FIXER on RocketChip, a RISC-V SoC platform, by leveraging the integrated Rocket Custom Coprocessor (RoCC) to detect and prevent attacks. Compared to existing software based solutions, FIXER reduces energy overhead by 60% at minimal execution time (1.5%) and area (2.9%) overheads.

This paper presents a multilayer protection approach to guard programs against Return-Oriented Programming (ROP) attacks. Upper layers validate most of a program's control flow at a low computational cost; thus, not compromising runtime. Lower layers provide strong enforcement guarantees to handle more suspicious flows; thus, enhancing security. Our multilayer system combines techniques already described in the literature with verifications that we introduce in this paper. We argue that modern versions of x86 processors already provide the microarchitectural units necessary to implement our technique. We demonstrate the effectiveness of our multilayer protection on a extensive suite of benchmarks, which includes: SPEC CPU2006; the three most popular web browsers; 209 benchmarks distributed with LLVM and four well-known systems shown to be vulnerable to ROP exploits. Our experiments indicate that we can protect programs with almost no overhead in practice, allying the good performance of lightweight security techniques with the high dependability of heavyweight approaches.

Control-hijacking attacks include code injection attacks and code reuse attacks. In recent years, with the emergence of the defense mechanism data-execution prevention(DEP), code reuse attacks have become mainstream, such as return-oriented programming(ROP), Jump-Oriented Programming(JOP), and Counterfeit Object-oriented Programming(COOP). And a series of defensive measures have been proposed, such as DEP, address space layout randomization (ASLR), coarse-grained Control-Flow Integrity(CFI) and fine-grained CFI. In this paper, we propose a new attack called function-oriented programming(FOP) to construct malicious program behavior. FOP takes advantage of the existing function of the C program to induce attack. We propose concrete algorithms for FOP gadgets and build a tool to identify FOP gadgets. FOP can successfully bypass coarse-grained CFI, and FOP also can bypass some existing fine-grained CFI technologies, such as shadow stack technology. We show a real-world attack for proftpd1.3.0 server in the Linux x64 environment. We believe that the FOP attack will encourage people to come up with more effective defense measures.

Virtual switches are a crucial component of SDN-based cloud systems, enabling the interconnection of virtual machines in a flexible and "software-defined" manner. This paper raises the alarm on the security implications of virtual switches. In particular, we show that virtual switches not only increase the attack surface of the cloud, but virtual switch vulnerabilities can also lead to attacks of much higher impact compared to traditional switches. We present a systematic security analysis and identify four design decisions which introduce vulnerabilities. Our findings motivate us to revisit existing threat models for SDN-based cloud setups, and introduce a new attacker model for SDN-based cloud systems using virtual switches. We demonstrate the practical relevance of our analysis using a case study with Open vSwitch and OpenStack. Employing a fuzzing methodology, we find several exploitable vulnerabilities in Open vSwitch. Using just one vulnerability we were able to create a worm that can compromise hundreds of servers in a matter of minutes. Our findings are applicable beyond virtual switches: NFV and high-performance fast path implementations face similar issues. This paper also studies various mitigation techniques and discusses how to redesign virtual switches for their integration.

Code reuse attacks based on return oriented programming (ROP) are becoming more and more prevalent every year. They started as a way to circumvent operating systems protections against injected code, but they are now also used as a technique to keep the malicious code hidden from detection and analysis systems. This means that while in the past ROP chains were short and simple (and therefore did not require any dedicated tool for their analysis), we recently started to observe very complex algorithms – such as a complete rootkit – implemented entirely as a sequence of ROP gadgets. In this paper, we present a set of techniques to analyze complex code reuse attacks. First, we identify and discuss the main challenges that complicate the reverse engineer of code implemented using ROP. Second, we propose an emulation-based framework to dissect, reconstruct, and simplify ROP chains. Finally, we test our tool on the most complex example available to date: a ROP rootkit containing four separate chains, two of them dynamically generated at runtime.

Despite a long history and numerous proposed defenses, memory corruption attacks are still viable. A secure and low-overhead defense against return-oriented programming (ROP) continues to elude the security community. Currently proposed solutions still must choose between either not fully protecting critical data and relying instead on information hiding, or using incomplete, coarse-grain checking that can be circumvented by a suitably skilled attacker. In this paper, we present a light-weighted memory protection approach (LMP) that uses Intel's MPX hardware extensions to provide complete, fast ROP protection without having to rely in information hiding. We demonstrate a prototype that defeats ROP attacks while incurring an average runtime overhead of 3.9%.