Protecting the Control Flow of Embedded Processors against Fault Attacks

Werner, Mario; Wenger, Erich; Mangard, Stefan

doi:10.1007/978-3-319-31271-2_10

Cited by 18 publications

(36 citation statements)

References 8 publications

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“…Control-flow integrity has been widely studied since the seminal work of Abadi et al [19], in various contexts of threat, and is still currently a hot topic of research [20,21,22,23]. As we focus on a smart card subject to physical attacks, it induces a specific attacker model and requires specific solutions.…”

Section: Related Workmentioning

confidence: 99%

“…Thus, a control-flow attack that leads to the execution of only a subpart of a basic block will be detected. Several solutions based on dedicated hardware have been proposed [42,43,44,21,20]. Although they have a lower overhead, they require hardware modifications, and thus, are impractical for smart cards based on off-the-shelf hardware.…”

Section: Code Integrity and Control-flow Securingmentioning

confidence: 99%

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Formally verified software countermeasures for control-flow integrity of smart card C code

Heydemann¹,

Lalande²,

Berthomé³

2019

Computers & Security

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Fault attacks can target smart card programs to disrupt an execution and take control of the data or the embedded functionalities. Among all possible attacks, control-flow attacks aim at disrupting the normal execution flow. Identifying harmful control-flow attacks and designing countermeasures at the software level are tedious and tricky for developers. In this paper, we propose a methodology to detect harmful inter-and intra-procedural jump attacks at the source code level and automatically inject formally proven countermeasures into a C code. The proposed software countermeasures protect the integrity of individual statements at the granularity of single C statements. They support many control-flow constructs of the C language. The countermeasure scheme can detect an attack early either inside a control-flow construct or only at its exit. The secured source code defeats 100% of attacks that jump over at least two C source code statements. Experiments showed that the resulting code is also hardened against unexpected function calls and jump attacks at the assembly code level. Securing a source code automatically and extensively with our scheme degrades the performance. The performance overhead of our countermeasures on three well-known encryption algorithms available in C ranged from +41% to +138% on an x86 platform and from +45% to +217% on an ARM-v7 platform. However, combining code rewriting with hardening of sensitive code regions identified by the weakness detection step enables an application to be fully hardened while limiting the overhead.

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Section: Related Workmentioning

confidence: 99%

Section: Code Integrity and Control-flow Securingmentioning

confidence: 99%

Formally verified software countermeasures for control-flow integrity of smart card C code

Heydemann¹,

Lalande²,

Berthomé³

2019

Computers & Security

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“…Another common approach to enforce CFI is to augment the processor with hardware monitors [7], [33], [43]. Typically, these monitors continuously check that the processor behaves as expected and raise an alert when an error is observed.…”

Section: Related Workmentioning

confidence: 99%

Sponge-Based Control-Flow Protection for IoT Devices

Werner

Unterluggauer

Schaffenrath

et al. 2018

2018 IEEE European Symposium on Security and Privacy (EuroS&P)

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Embedded devices in the Internet of Things (IoT) face a wide variety of security challenges. For example, software attackers perform code injection and code-reuse attacks on their remote interfaces, and physical access to IoT devices allows to tamper with code in memory, steal confidential Intellectual Property (IP), or mount fault attacks to manipulate a CPU's control flow.In this work, we present Sponge-based Control Flow Protection (SCFP). SCFP is a stateful, sponge-based scheme to ensure the confidentiality of software IP and its authentic execution on IoT devices. At compile time, SCFP encrypts and authenticates software with instruction-level granularity. During execution, an SCFP hardware extension between the CPU's fetch and decode stage continuously decrypts and authenticates instructions. Sponge-based authenticated encryption in SCFP yields fine-grained control-flow integrity and thus prevents code-reuse, code-injection, and fault attacks on the code and the control flow. In addition, SCFP withstands any modification of software in memory. For evaluation, we extended a RISC-V core with SCFP and fabricated a real System on Chip (SoC). The average overhead in code size and execution time of SCFP on this design is 19.8 % and 9.1 %, respectively, and thus meets the requirements of embedded IoT devices.

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“…CFI protection schemes [1] typically protect the execution of code against software attacks. However, recent work extends these countermeasures in the context of fault attacks, where they try to protect the sequence of basic blocks or even the sequence of instructions [10], [19], [23].…”

Section: A Code Protection With Control-flow Integritymentioning

confidence: 99%

“…We included all transformations to the LLVM compiler ( Figure 3) and evaluated this scheme using an ARMv7-M instruction set architecture (ISA) simulator. We use a software-centered GPSA CFI scheme similar to the one in [23]. The branch protection is purely implemented in software and does not require hardware modifications.…”

Section: Implementation and Evaluationmentioning

confidence: 99%

Securing conditional branches in the presence of fault attacks

Schilling

Werner

Mangard

2018

2018 Design, Automation &Amp; Test in Europe Conference &Amp; Exhibition (DATE)

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In typical software, many comparisons and subsequent branch operations are highly critical in terms of security. Examples include password checks, signature checks, secure boot, and user privilege checks. For embedded devices, these security-critical branches are a preferred target of fault attacks as a single bit flip or skipping a single instruction can lead to complete access to a system. In the past, numerous redundancy schemes have been proposed in order to provide controlflow-integrity (CFI) and to enable error detection on processed data. However, current countermeasures for general purpose software do not provide protection mechanisms for conditional branches. Hence, critical branches are in practice often simply duplicated.We present a generic approach to protect conditional branches, which links an encoding-based comparison result with the redundancy of CFI protection mechanisms. The presented approach can be used for all types of data encodings and CFI mechanisms and maintains their error-detection capabilities throughout all steps of a conditional branch. We demonstrate our approach by realizing an encoded comparison based on AN-codes, which is a frequently used encoding scheme to detect errors on data during arithmetic operations. We extended the LLVM compiler so that standard code and conditional branches can be protected automatically and analyze its security. Our design shows that the overhead in terms of size and runtime is lower than state-of-the-art duplication schemes.

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Protecting the Control Flow of Embedded Processors against Fault Attacks

Cited by 18 publications

References 8 publications

Formally verified software countermeasures for control-flow integrity of smart card C code

Formally verified software countermeasures for control-flow integrity of smart card C code

Sponge-Based Control-Flow Protection for IoT Devices

Securing conditional branches in the presence of fault attacks

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